16

Report Author: Veronica Smith

Report Date: January 30, 2025

Table of Contents

Introduction

Everyone wants to have glowing and radiant skin. Skin is the body’s largest organ, and serves as an outward indicator of overall health. There is no standardized measure or definition of skin radiance; however, radiant skin is generally considered to be smooth, elastic, even-textured, and have a natural shine that occurs as a function of internal processes.¹ The outermost layer of the skin is called the stratum corneum, and acts as a physical barrier against environmental stressors such as UV radiation and pollution.² Below the stratum corneum, proteins such as collagen are responsible for maintaining the skin’s elasticity and firmness.³ When skin is properly hydrated and nourished, it is better able to reflect light which creates a glowing effect.

While genetics play a role in skin health, lifestyle choices account for a large portion of its appearance. Things like poor sleep habits, excessive sun exposure, smoking, and poor diet all have an impact on skin health. Poor sleep increases cortisol levels, which increases inflammation, breakouts, and impairs the skin barrier, resulting in dull skin and fine lines.⁴ Exposure to UV rays damages skin cells, which accelerates signs of aging such as pigmentation, dry skin and premature wrinkles, and also increases the risk of skin cancer.⁵ Smoking reduces blood flow to the skin, which causes an increase in the degradation of collagen and elastin due to the reduced access to oxygen and nutrients, causing wrinkles, dullness, and sagging.⁶ Finally, poor diets high in sugar, refined carbs, and processed foods can increase inflammation resulting in acne and oily skin and accelerate skin aging.⁷ In this literature review, recommendations for dietary nutrients will be provided with the goal of supporting radiant, glowing skin.

Significance of the Topic

Radiant and glowing skin is viewed societally as a sign of good health and self-care. As such, skincare is heavily invested upon as part of a daily routine. According to a report by Grand View Research, the global skincare market was valued at approximately $136 billion in 2022.⁸ While women currently dominate this market at more than 60%, men are increasingly gaining interest in this area as well. This growing trend highlights the importance of skin health across all demographics, and demonstrates the need for effective solutions for improving skin health from accessible options such as the diet.

Skin is the largest organ, and provides a physical barrier against environmental threats such as UV radiation and harmful microbes.⁹ UV radiation exposure occurs when outdoors in the sunlight. These rays can penetrate the skin and damage DNA within cells, resulting in sunburns, premature aging, and skin cancer. Overexposure to UV rays breaks down collagen and elastin which are proteins that maintain the elasticity and firmness of skin. It is estimated that sun exposure is responsible for up to 80% of visible skin aging.¹⁰

In addition to UV radiation, environmental pollutants like particulates and chemicals can harm skin health. It is estimated that the risk of skin pigmentation disorders is increased by 20% due to exposure to air pollution.¹¹ These pollutants generate molecules called free radicals, which damage cellular structures such as lipids, proteins and DNA. Over time, this oxidative stress results in inflammation, hyperpigmentation, and dullness.

The appearance of skin has significant societal and psychological implications. Clear, radiant skin is often associated with youth and attractiveness, which influences self-esteem and social interactions. Research indicates that those with healthy skin are more likely to be viewed positively in professional and personal situations.¹² In contrast, skin conditions such as acne can impact mental health, leading to anxiety or reduced self-confidence.¹³

Glowing and radiant skin is not just an aesthetic goal, but also an indicator of internal health. A variety of factors such as hydration, stress, and nutrition have a direct impact on the appearance and function of skin. For example, dehydration reduces skin elasticity and impairs its ability to act as an effective barrier, while a diet lacking in vitamins and antioxidants can accelerate aging and increase susceptibility to oxidative damage.¹⁴ Research has shown that people who consume diets rich in fruits and vegetables have a more radiant and even skin tone.¹⁵ Additionally, a balanced diet rich in nutrients such as vitamins, minerals, proteins, and omega-3 fatty acids supports collagen production, protects against oxidative stress, and enhances the texture and tone of skin.¹⁶

Dietary strategies play an important role in influencing skin health, and offer an internal approach to complement topical treatments. A range of studies have demonstrated the relationship between nutrition and skin health, where specific nutrients are able to protect against oxidative damage, improve hydration, and protect and promote collagen synthesis. This literature review examines key nutrients that can be easily obtained through diet or supplementation including vitamins, antioxidants, and fatty acids, and their roles in supporting the pursuit of glowing and radiant skin.

Specific Nutrient: Vitamins A, C, and E

What is it

Vitamins are micronutrients that are essential for various functions within the body, including metabolism, immune function, and cellular maintenance. Some vitamins, such as A and E, are fat-soluble, meaning that they are stored in fatty tissues in the body and are retained for a significant amount of time. Conversely, other vitamins like vitamin C are water soluble and need to be consumed more regularly as they are quickly expelled in the urine. These vitamins are found in high amounts in various fruits, vegetables, and animal sources, and are widely available in the form of over the counter supplements. Historically, these vitamins have been recommended for their various functions, including improving night vision, immune function, and skin healing.

Vitamins A, C, and E, are all used as ingredients in topical skin care products. Retinol, or preformed vitamin A, is well known for its ability to improve signs of aging such as wrinkles, fine lines, and uneven skin tone.¹⁷ Dietary vitamin A is available in two forms: preformed vitamin A such as retinol and retinyl esters which are sourced from animals, and provitamin A carotenoids like beta-carotene which are found in plants, and are subsequently broken down into vitamin A by the body.¹⁸ Similarly, vitamin C is also a frequent component in topical products for its ability to reduce the signs of aging and reduction of hyperpigmentation.¹⁹ While less routinely used as a topical agent, Vitamin E is often sometimes included in formulations as it is thought to improve moisturization. Vitamins A, C, and E are all found in healthy skin and play a role in its maintenance.

How it Works

Vitamins A, C, and E impact skin health in a variety of ways, including immune regulation and microbiome support, development and maintenance of skin tissues, combating oxidative stress, and increasing collagen synthesis.

Vitamin A plays a crucial role in maintaining collagen health by stimulating its synthesis, reducing degradation, and enhancing skin structure. Retinoids, the biologically active forms of vitamin A, activate fibroblasts, increase collagen production, and inhibit matrix metalloproteinases (MMPs), enzymes responsible for collagen breakdown.²⁰ Immune regulation also relies on vitamin A, as it plays a key role in the function of certain pattern recognition receptors (PRRs) involved in detecting pathogens and in the development of dendritic cells.²¹ By supporting the function of PRRs and the development of dendritic cells, vitamin A enhances the skin’s ability to detect and respond to harmful microorganisms, reducing the risk of infections and inflammation that can compromise skin health and appearance. Furthermore, some epidermal cells excrete a small protein called resistin-like molecule 𝛼 (RELM𝛼), which is an antimicrobial protein that protects against skin infection and is dependent on vitamin A.²² Epidermal cell growth and differentiation is dependent on vitamin A, leading to the development and maintenance of skin tissues.²³ Vitamin A is also an antioxidant, which combats oxidative stress by neutralizing free radicals which are harmful molecules that can damage cells, DNA, and proteins.²⁴ These free radicals are formed in part through UV damage, smoking, and other environmental effects, and so the antioxidant properties of these vitamins may provide some photoprotective effect.²⁵

Vitamin C has been shown to stimulate collagen production, which improves skin elasticity and reduces the appearance of wrinkles.²⁶ Vitamin C plays a critical role in collagen biosynthesis by serving as a cofactor for the enzymes prolyl hydroxylase and lysyl hydroxylase.²⁷ These enzymes catalyze the formation of hydroxyproline and hydroxylysine, modified amino acids essential for stabilizing the triple-helix structure of collagen. This structural stability enhances the thermal resilience and mechanical strength of collagen fibers.²⁸ Additionally, vitamin C promotes collagen production by upregulating the transcription of collagen genes and stabilizing procollagen mRNA, leading to increased protein synthesis.²⁹ Beyond its role in collagen synthesis, vitamin C may also regulate matrix metalloproteinases (MMPs), enzymes responsible for tissue breakdown, further supporting the maintenance of healthy connective tissue.³⁰ Finally, vitamin C is also an antioxidant which reduces oxidative cellular stress.³¹

Vitamin E plays a role in skin health due to its potent antioxidant properties, which protects the skin from oxidative stress and helps to maintain skin elasticity and structure.³² Vitamin E also regulates inflammation by inhibiting the activation of pro-inflammatory enzymes and cytokines, potentially contributing to a calmer, more resilient complexion.³³ Moreover, tocotrienols, a subgroup of vitamin E, have been shown to modulate matrix metalloproteinases (MMPs), enzymes responsible for collagen breakdown, thereby slowing down the skin aging process.³⁴

The cumulative effect of these functions is the appearance of more youthful, healthy skin. These vitamins are found in a variety of food sources, and can also be found in the form of multivitamin or stand-alone vitamin supplements.

What the Research is Telling us

There is a wealth of in vitro research that supports the use of dietary vitamins for improved skin health. However, while the available clinical trial literature generally supports the hypothesis that orally ingested vitamin supplementation aids in the appearance of skin, recent studies are typically limited by a small sample size, or by treatment with a cocktail of different compounds.

Although recent literature is limited, older literature is supportive of the use of high-dose vitamin A for skin health, including improving the appearance of acne. A 2022 review article drew on data from nine clinical studies, ranging in date from 1943 – 1981, and one case study from 2019, to evaluate the efficacy, dosing, safety, and affordability of oral vitamin A.³⁵ An improvement in acne was observed in 83% of patients, with higher doses (300,000 – 500,000 IU daily, yielding the most significant results. Effective doses ranged from 36,000 IU to 500,000 IU daily, with maintenance doses of 25,000 – 50,000 IU suggested to reduce relapse, which occurred in 20-40% of patients. While some adverse events such as mucocutaneous issues and elevated triglycerides or liver enzymes were noted, these effects were dose-dependent and resolved with dose adjustment. The authors note that while isotretinoin has generally superior efficacy, oral vitamin A demonstrated comparable benefits at high doses at a significantly more affordable cost. These results indicate that while oral vitamin A supplementation is a viable option for the treatment of acne, careful monitoring and further research are essential to optimize its use and ensure safety.

In a 1997 landmark study, a large randomized, double-blind, controlled trial investigated the role of vitamin A in reducing the risk of nonmelanoma skin cancers in individuals at moderate risk.³⁶ The study enrolled 2,297 participants in Arizona with a median age of 63 years, all with a history of over 10 actinic keratoses and up to two prior squamous cell carcinoma (SCC) or basal cell carcinoma (BCC) occurrences. Participants received either 25,000 IU of oral retinol or a placebo daily for up to five years. While no significant differences were observed in new BCC occurrences between the groups, the retinol group exhibited a 26% reduced risk of developing new SCCs (hazard ratio = 0.74, 95% CI = 0.56-0.99; P = 0.04).

A subsequent study assessed escalating doses of oral vitamin A to address actinic damage and improve skin health.³⁷ A total of 129 participants aged over 50 with moderate to severe sun damage were randomized to receive a placebo or one of three vitamin A doses (25,000, 50,000, or 75,000 IU) daily for 12 months. The results showed a dose-dependent reduction in actinic damage (skin damage caused by prolonged exposure to UV radiation), with reductions of 65% in the 25,000 IU group (P < 0.004), 81% in the 50,000 IU group (P < 0.001), and 79% in the 75,000 IU group (P < 0.001) with no severe toxicities. These results indicate that high-dose vitamin A supplementation may aid in skin cancer prevention. Additionally, karyometric analysis revealed decreased nuclear abnormalities, signifying reduced DNA damage in skin cells. Higher doses of vitamin A also upregulated retinoic acid receptor and retinoid X receptor expression, indicating that these are the molecular mechanisms behind the reduced actinic damage. This study supports the potential role of vitamin A in preventing the progression of skin cancer through the upregulation of retinoid receptors and reduction of nuclear actinic damage. It should be noted that the dosages used in this study are well above the upper daily limit, and should not be attempted without the supervision of a physician.

To evaluate the effect of oral vitamin A supplementation on skin appearance and aging, a clinical trial consisting of 60 subjects was divided into two groups: those receiving only a 0.02% topical retinoic acid treatment, and those receiving the same topical retinoid along with once daily supplementation with 50,000 IU vitamin A and 50 mg vitamin E over a 12 week period.³⁸ At the end of the study period, patients receiving the additional oral vitamin supplement showed a greater improvement in skin appearance (P < 0.01) as determined by a reduction in Skin Aging Global Score (SAGS). The authors acknowledge some limitations of this study including the lack of an oral placebo and that the study was not fully blinded. These results indicate that dietary vitamin supplementation enhances the role of topical retinoids improving the appearance of aging skin.

Despite extensive in vitro research supporting vitamin C’s role in skin health, including collagen synthesis, large-scale human clinical trials validating these findings remain scarce. Most studies evaluating vitamin C’s impact on skin health involve formulations containing multiple active components, such as hydrolyzed collagen or gelatin, rather than isolating vitamin C’s effects.

Two association studies examined the relationship between nutrient intake and visible signs of skin aging. The first study utilized data from the NHANES I study (1971-1974), focusing on middle-aged women from 40-74 years and assessed dietary habits using 24-hour dietary recalls, along with dermatological evaluations.³⁹ This study revealed that higher intakes of vitamin C were associated with a lower likelihood of wrinkles (OR: 0.89; 95% CI: 0.82-0.96) and senile dryness (OR: 0.93; 95% CI: 0.87-0.99). These associations were observed to remain significant even after adjusting for age, sun exposure, race, education, income, and other factors. A second study explored the relationship between dietary patterns and skin wrinkling due to actinic damage, focusing on populations from different cultural and geographical backgrounds.⁴⁰ This study assessed 453 participants: 177 Greek subjects living in Melbourne, 69 Greek subjects living in Greece, 48 Anglo-Celtic subjects living in Melbourne, and 159 Swedish subjects living in Sweden. Skin wrinkling was assessed using standardized grading scales by trained dermatologists, and dietary patterns were recorded using validated food frequency questionnaires. This study revealed that vitamin C intake was negatively associated with actinic skin damage. These studies together indicate that adequate vitamin C consumption is linked to more youthful looking skin.

One small, non-controlled study assessed the effectiveness of an oral supplement containing collagen peptides, vitamin C, A. chilensis, and H. sabdariffa in improving dermal thickness, skin firmness, and elasticity in aging skin.⁴¹ A. chilensis and H. sabdariffa are two plants known for their high antioxidant content, commonly known as maqui berry and hibiscus. This 12-week study involved 35 women aged 35-65 with visible signs of skin aging. Participants consumed one sachet of the supplement daily, and outcomes were measured using cutometry for skin firmness and elasticity and ultrasound for dermal thickness. Results showed significant improvements: skin firmness increased by 38% (P < 0.001), elasticity by 39% (P < 0.001), and dermal thickness by 22% in the submental region and 25% in the malar region (both P < 0.001). Additionally, 94% of participants reported moderate to significant improvements in skin firmness and elasticity.

Another small randomized, double-blind trial involving eight healthy young men investigated the effects of gelatin and vitamin C supplementation on collagen synthesis and the mechanical properties of musculoskeletal tissues.⁴² Participants consumed 15 g of gelatin enriched with vitamin C before intermittent exercise. The study revealed that supplementation significantly enhanced collagen synthesis, with a twofold increase in blood markers of collagen production. The researchers attributed this effect to the essential amino acids in gelatin providing building blocks for collagen, while vitamin C facilitated enzymatic cross-linking for collagen stability.

A small study investigated the effects of oral vitamin C supplementation on the radical-scavenging activity of human skin.⁴³ Radical scavenging activity is the ability of a compound to neutralize free radicals, thereby preventing oxidative damage to biomolecules such as lipids, proteins, and DNA. This study assessed the impact of two different daily doses of vitamin C (100 mg and 180 mg) compared to a placebo over four weeks on 33 healthy volunteers. Vitamin C was observed to significantly enhance the skin’s radical-scavenging capacity, with a daily intake of 100 mg increasing activity by 22%, while 180 mg led to a 37% increase after 4 weeks (P < 0.05). While the carotenoid content in the skin was increased in both vitamin C groups, it did not reach statistical significance as compared to the placebo. This study demonstrates that oral vitamin C supplementation significantly boosts the skins’ antioxidant defenses in a dose-dependent manner, highlighting its potential as a non-invasive strategy to protect the skin from oxidative stress and environmental damage.

Although larger clinical studies are needed to confirm these effects, existing in vitro research and small human trials suggest that vitamin C likely supports collagen maintenance and skin health. Its favorable safety profile further highlights its potential as a beneficial component of dietary or supplemental regimens for improving skin and connective tissue health.

Similarly, in a small, randomized, double-blind placebo-controlled study, supplementation with vitamin C, vitamin E, and zinc was observed to decrease wound healing time of children suffering from burn wounds (P < 0.001).⁴⁴ This study consisted of 32 patients, approximately half of whom received a supplement of vitamin C (1.5 x UL), vitamin E (1.35 x UL) and zinc (2 x RDA) administered over 7 days, starting on the second day of hospitalization. In addition to the consideration of wound healing time, oxidative stress was measured by plasma total antioxidant capacity and malondialdehyde level. Malondialdehyde is a byproduct of lipid peroxidation, and serves as a biomarker for oxidative damage. In the group receiving the supplement, a decrease in malondialdehyde was observed, indicating a decrease in lipid peroxidation (P = 0.006) as well as increased vitamin E concentration (P = 0.016). These results indicate that supplementation of vitamins C, E and zinc may enhance protection against oxidative stress, resulting in decreased wound healing time, however larger studies should be conducted to further validate these findings.

A study in mice investigated the effects of vitamin E on stress-induced changes in skin thickness, elasticity, and collagen levels.⁴⁵ Mice were divided into four groups based on stress exposure and vitamin E supplementation: a control group, a stress-only group, a vitamin E- only group, and a group receiving both stress and vitamin E. The supplementation consisted of 0.5 g/day of alpha-tocopherol acetate in meals, while stress was induced by immobilization for 40 minutes daily over eight weeks. Stress significantly increased epidermal thickness by up to 200%, while vitamin E supplementation reduced this thickening by 15-49%. Dermal thickness, which decreased by 8-26% under stress, was better preserved in mice receiving vitamin E. Skin elasticity, which dropped by 50% in chronically stressed mice, also showed improvement with vitamin E supplementation. Although vitamin E had little direct impact on restoring collagen content (which decreased by approximately 30% due to stress), these findings suggest that its antioxidant properties play a key role in maintaining healthy skin under stress conditions.

Furthermore, a systematic review explored the benefits of tocotrienols, a subfamily of vitamin E, on skin health.⁴⁶ Tocotrienols have been shown to enhance collagen synthesis, reduce its degradation by inhibiting matrix metalloproteinases (MMPs), and protect fibroblasts from oxidative damage. Gamma-tocotrienol in particular upregulates collagen-related genes and preserves skin elasticity and structure. Additionally topical tocotrienols have been found to improve skin hydration, reduce transepidermal water loss, and minimize skin roughness and wrinkle depth.

Overall, further research is needed to determine the full relationship between skin health and vitamins A, C and E. However, in vitro and small clinical trials are generally supportive of their utility for skin health.

Dosage Recommendation Based on Research

The recommended daily allowance (RDA) for vitamin A is measured in retinol activity equivalents (RAE). The National Institutes of Health (NIH) recommends 900 micrograms RAE for adult men, and 700 micrograms RAE for adult women.⁴⁷ For women who are pregnant or lactating, higher intakes of vitamin A may be necessary. While some studies utilize very high levels of vitamin A safely, this should not be attempted outside the supervision of a physician. Because vitamin A is fat soluble, it is best consumed along with healthy fats for optimal absorption. Additionally, cooking can increase the bioavailability of beta-carotene from foods.

While the NIH recommends 90 mg per day of vitamin C for men and 75 mg per day for women, some research indicates that a higher dose of 100 – 200 mg per day may be more beneficial.⁴⁸ Although this dose is higher than the RDA, it is still well below the daily maximum of 2,000 mg per day. Vitamin C is sensitive to heat, therefore it is recommended to consume foods containing vitamin C raw for maximum benefit. For those who smoke and women who are pregnant or lactating, higher intakes of vitamin C may be needed.

The NIH recommends 15 mg per day of vitamin E for both men and women for general maintenance. For women who are lactating, higher intakes of vitamin E may be recommended. There are currently no well-determined recommendations on daily consumption of vitamin E for skin health, however one study utilized 1.35 x UL of vitamin E in combination with other nutrients to decrease wound healing time.⁴⁹ Oxidized vitamin E is regenerated by vitamin C, and so it is recommended to pair these vitamins for increased effectiveness.⁵⁰

Table 1 Dosage Recommendation for Vitamins A, C, and E

* These values exceed the UL and should not be attempted without the supervision of a physician. These values are reported in International Units (IU), which corresponds to varying doses in micrograms depending on the source. For retinol and supplemental beta-carotene, 1 IU = 0.3 mcg RAE; for dietary beta-carotene, 1 IU = 0.05 mcg RAE.⁵¹

**This dose is extrapolated from a dosage used in conjunction with vitamin C and zinc to support wound healing in children. This dose exceeds the UL and should not be attempted without physician supervision.

Facts and Misconceptions

A common myth in skincare is that the topical application of vitamins is more beneficial for skin than those obtained through diet. While topical application of vitamins through the use of serums or oils can often result in more immediately observable results, they lack the systemic effects of dietary vitamins which are important for long-term skin health and combating environmental stressors. The ideal regimen would include both topical and dietary vitamins for the most comprehensive skin protection.

While dietary vitamins can improve skin appearance, excessive vitamin consumption, particularly those which are fat soluble such as vitamin A and vitamin E, can accumulate in the body and cause toxicity. Excessive intake of vitamin A can cause dry and peeling skin, hair loss, and liver damage. Vitamin E toxicity can have detrimental effects on the liver and kidneys, as well as an increased risk of hemorrhage. Vitamin C is water soluble, and so it is not thought to be associated with serious adverse events at high levels. As with any supplement, excessive consumption should be avoided unless a supervising physician has prescribed higher doses. The recommended daily allowance (RDA) refers to the amount of each nutrient you should consume each day from all sources. This value takes absorption into account, so exceeding this value is not necessary to ensure adequate nutrition.

Food Sources

Plant sources high in vitamin A:

• Carrots – 509 mcg per 1 medium carrot (~61 g)

• Sweet potato – 1,403 mcg per 1 medium potato (~100 g)

• Pumpkin – 953 mcg per 1/2 cup serving

• Butternut squash – 1,144 mcg per 1 cup serving

• Spinach – 573 mcg per 1/2 cup serving

Animal sources high in vitamin A:

• Beef liver – 6,582 mcg per 3 ounce serving

• Salmon – 59 mcg per 3 ounce serving

Plant sources high in vitamin C:

• Guava – 125 mg per one medium fruit (~55 g)

• Red bell peppers – 152 mg per 1 medium pepper (~75 g)

• Strawberries – 89 mg per 1 cup serving

• Kiwi – 56 mg per 1 medium fruit (~71 g)

• Oranges – 70 mg per 1 medium fruit (~131 g)

• Papaya – 88 mg per 1 cup serving

• Mango – 60 mg per 1 cup serving

• Brussels sprouts – 48 mg per 1/2 cup, cooked

Plant sources high in vitamin E:

• Sunflower seeds – 7.4 mg per 1 ounce serving

• Almonds – 7.3 mg per 1 ounce serving

• Hazelnuts – 4.3 mg per 1 ounce serving

• Pine nuts – 2.6 mg per 1 ounce serving

• Avocado – 2.1 mg per 1/2 fruit (~68 g)

• Peanuts – 2.2 mg per 1 ounce serving

Supplemental Sources

Vitamin A supplements are commonly available as multivitamins or standalone supplements, such as cod liver oil which is widely available as a capsule or liquid. Cod liver oil is often rich in preformed vitamin A, which is readily absorbed by the body. Additionally, vitamin A can be found in fortified foods which are enriched such as breakfast cereals or plant or animal based milks.⁵² Supplements and fortified foods commonly contain preformed vitamin A (retinyl palmitate and retinyl acetate), provitamin A beta-carotene, or a combination. Synthetic preformed vitamin A forms like retinyl palmitate and retinyl acetate exhibit high bioavailability due to efficient absorption.⁵³ In contrast, the bioavailability of beta-carotene is lower and subject to variability, as it requires conversion to active vitamin A within the body.

Vitamin C supplements are available in a variety of forms, such as tablets, capsules, powders, and gummies. It is most commonly sold in its pure form as ascorbic acid which is highly bioavailable, but can also be found in buffered form for sensitive stomachs, or in various formulations which are thought to increase absorption or bioavailability.⁵⁴ No difference in bioavailability has been observed for ascorbic acid from natural sources such as kiwi as compared to supplemental sources.⁵⁵

Vitamin E supplements are most commonly available as softgels or capsules, but can also be found in the form of liquid drops or powders. Natural vitamin E (d-alpha-tocopherol) generally has better bioavailability than synthetic varieties, which may be particularly important for those seeking optimal benefits.⁵⁶

Side Effects

Vitamins are generally regarded as safe when taken as recommended and when consumed as part of the diet. However, they can interact with some medications, and excessive consumption can have significant side effects.⁵⁷ Due to their status as antioxidants, you should consult with your doctor before taking any of these vitamin supplements as they have the potential to interact with drugs such as those used for chemotherapy and radiotherapy, or statins.

Vitamin C is water soluble, and so it is not thought to be associated with serious adverse events at high levels, and symptoms of excessive consumption are generally gastrointestinal in nature such as nausea, diarrhea, and abdominal cramping.⁵⁸

Vitamin E is a fat soluble vitamin, and is therefore more likely to build up in the body. Excessive consumption of vitamin E through supplements can cause hemorrhage and disrupt blood coagulation, potentially increasing the risk of uncontrolled bleeding.⁵⁹ Furthermore, it has the potential to interact with medications that affect blood clotting such as anticoagulant and antiplatelet drugs, potentially amplifying their effects.

Acute vitamin A toxicity can result in symptoms such as headache, dizziness, blurred vision, and coordination problems, while chronic toxicity can cause dry skin, aching joints and muscles, depression, fatigue, and liver damage.⁶⁰ High doses of vitamin A should not be combined with drugs that are hepatotoxic or other oral medications containing retinoids. While beta-carotene is not known to be teratogenic, preformed vitamin A that exceeds the RDA can cause congenital birth defects.

Legal Status and Availability

Vitamins A, C, and E are generally widely available as over-the-counter (OTC) supplements, however physicians may prescribe higher dose supplements for therapeutic use. Because dietary supplements are not subject to the same regulations as pharmaceuticals, there may be variation between the true ingested dose and the product labeling. This may be due to intentional oversaturation by the manufacturer to ensure continued potency by the expiration date, or degradation of the product over time.

Bottom Line

Vitamins A, C, and E have the potential to improve the appearance of skin over time when consumed as part of a healthy and balanced diet. In addition to other mechanisms, these vitamins function as antioxidants, which reduce free radicals in the body and thereby reduce damage to cells, DNA and proteins, improving the appearance of skin. Their utility in skin health is widely supported by the literature, although larger and more comprehensive clinical studies are needed. Additionally, further research is needed to determine the optimal dosage recommendations for the support of healthy skin. Excessive consumption of these vitamins can result in side effects, however they are generally regarded as safe and are found in a number of typical food sources, and are freely available as OTC supplements.

Specific Nutrient: Omega-3 Fatty Acids

What is it

Omega-3 fatty acids, which belong to a larger group known as polyunsaturated fatty acids (PUFAs), are healthy fats found in fish oils and some plant oils. Fish oils are high in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the active forms of omega-3, while seeds and nuts provide alpha-linoleic acid (ALA), which the body converts to EPA and DHA in the body, though not very efficiently.⁶¹ EPA and DHA may lower the risk of heart disease and offer other benefits like supporting brain health, fetal development, and reducing inflammation.⁶² Because inflammation plays a role in the appearance of skin, omega-3 fatty acids are of interest due to their ability to reduce inflammation.

How it works

The primary method through which omega-3s aid in skin health is through their anti-inflammatory activity. Omega-3s not only inhibit the production of pro-inflammatory compounds that are derived from omega-6 fatty acids, but they can also modulate the expression of both pro- and anti- inflammatory genes, and incorporate into cell membranes which impacts the signaling pathways involved in inflammation. ⁶³ Additionally, EPA and DHA serve as precursors to compounds called pro-resolving mediators, which actively resolve inflammation.⁶⁴ Evidence suggests that omega-3s are potentially useful for a number of dermatological applications, such as reducing UV-related inflammation, and protecting against photoaging and photoimmunosuppression.⁶⁵ Omega-3 supplementation has been reported to aid in the treatment of skin conditions such as psoriasis, atopic dermatitis, and acne.⁶⁶ While this review focuses primarily on skin health, omega-3s have positive effects on various functions in the body, and can aid in the management of many chronic conditions. These fatty acids can only be obtained through the diet, and are commonly found in fatty fish such as mackerel, salmon, and tuna, as well as plant-based sources such as flax seeds, chia seeds, and walnuts. In addition to natural sources such as these, supplements derived from fish, seed, or algal oil are also available.

What the Research is Telling us

The existing body of literature is generally favorable towards the use of omega-3 fatty acids for the prevention and treatment of certain skin conditions. A small, randomized, 10 week dietary intervention study was performed to evaluate the efficacy and safety of dietary omega-3 fatty acid and γ-linoleic acid on acne vulgaris. ⁶⁷ In this study, 45 participants with mild to moderate acne received either 2,000 mg DHA and EPA, borage oil containing 400 mg γ-linoleic acid, or no intervention. By the end of the 10 week study, both treatment groups had a significant decrease in both inflammatory and non-inflammatory acne lesions (P < 0.05) with no severe adverse events. Three participants exhibited mild reactions: one subject in the γ-linoleic acid treatment subset reported temporary diarrhea, while two subjects in the omega-3 treatment subset reported mild gastrointestinal discomfort, all of which resolved in a few days without intervention. In a larger trial, 2919 patients aged 45-60 were assessed to investigate the association of skin photoaging and daily intake of long chain n-3 polyunsaturated fatty acids (PUFAs).⁶⁸ At the study outset, the severity of facial skin photoaging was assessed by a clinical exam. The patients’ consumption of ALA, EPA, DPA and DHA was evaluated by a series of dietary record questionnaires over the first 2.5 years following the study. This study revealed that high intake of ALA in men and high intake of EPA in women was inversely associated with severe photoaging, suggesting a beneficial effect of PUFAs on skin aging.

In a randomized controlled trial, 45 women with dry skin were enrolled to evaluate the effect of ingested flaxseed oil and borage oil, supplements high in omega-3s, on skin health over 12 weeks.⁶⁹ In this study, 45 healthy women aged 18-65 with dry skin were assigned to one of three groups: placebo, a flaxseed treatment group, and a borage oil group, receiving 2.2 grams of the respective oil over 12 weeks. Both treatment groups demonstrated a significant increase in skin hydration as compared to the placebo group (P < 0.05), demonstrating that skin hydration can be positively impacted by dietary lipids. Additionally, erythema and blood flow decreased significantly in both treatment groups (P < 0.05), indicating anti-inflammatory effects. Because the effect on wrinkles were negligible, it was proposed that these interventions primarily improved hydration and barrier function.

A 2020 systematic review evaluated the use of omega-3 fatty acids for skin disease prevention and management.⁷⁰ This review evaluated a total of 38 studies which reported beneficial outcomes with fatty acid supplementation for the treatment of psoriasis, atopic dermatitis, acne, skin ulcers, and a reduced incidence of skin cancer. After assessing these sources, the authors concluded that omega-3 fatty acids are particularly valuable for UV photoprotection as well as the treatment of acne, and supplementation provides a safe, easy, and cost-effective method to do so.

Regarding UV photoprotection, a small clinical trial evaluated the effect of dietary omega-3 supplementation on UV-induced DNA damage in human subjects. ⁷¹ Over a period of 3 months, 42 participants were given 4g daily of purified omega-3 PUFA, EPA, or oleic acid as a control. For those participants receiving EPA, sunburn sensitivity was significantly reduced (P < 0.01), and p53 expression was also reduced (P < 0.01). P53 is a tumor suppressor protein that regulates DNA repair, cell cycle arrest, and apoptosis in response to genotoxic stress, preventing the accumulation of mutations that could lead to cancer. In this case, EPA’s ability to reduce its expression in UV-exposed skin suggests a reduction in oxidative DNA damage. Additionally, ex-vivo evaluation of the susceptibility of peripheral blood lymphocytes to UV radiation showed that participants who received EPA had a reduction in DNA strand breaks (P = 0.03). The authors concluded that these results indicate that EPA may result in protection against acute UV radiation genotoxicity, and that longer-term supplementation may reduce the risk of skin cancer. While limited in size, this study is further supported by a more recent pilot study in which omega-3 fatty acids were evaluated for their ability to reduce the risk of skin cancers in lung transplant recipients, who are at high risk due to immunosuppression medications.⁷² This study recruited 49 participants, 44 of whom were able to successfully complete the study. Of these 49 participants, 25 received a daily supplement containing 4 g omega-3 fatty acids (3.36 g EPA and DHA) while 24 received 4 g of olive oil as a placebo over a course of 12 months. At the conclusion of the study, 6 patients who received the omega-3 supplement developed skin cancers as compared to 11 patients in the placebo group (odds ratio = 0.34, 95% confidence interval = 0.09 – 1.3). While these results are not statistically significant, they demonstrate that a larger study investigating this relationship is warranted.

Two randomized, double-blind, placebo-controlled pilot studies investigated the effects of dietary krill oil, a supplement rich in omega-3s, on skin barrier function, hydration, and elasticity.⁷³ Each study initially recruited around 80 participants, with 51 completing Study 1 and 50 completing Study 2. Both studies spanned 12 weeks, with assessments conducted at baseline, 6 weeks, and 12 weeks. In Study 1, participants received either 1 g per day of krill oil or a placebo, while Study 2 used a higher dose of 2 g per day. Krill oil supplementation significantly reduced transepidermal water loss compared to placebo (Study 1: 4.42% reduction, P = 0.0027; Study 2: 8.63% reduction, P < 0.001), with a stronger effect observed in the higher-dose group, suggesting a dose-dependent response. Skin hydration improved significantly in both krill oil groups (Study 1: P = 0.01; Study 2: P < 0.001), as did skin elasticity (Study 1: P < 0.001; Study 2: P < 0.001). These benefits are attributed to increased ceramide and hyaluronic acid levels, modulation of collagen-related gene expression, and enhanced structural lipids in the stratum corneum. Furthermore, no significant adverse effects were reported, highlighting krill oil as a safe and effective supplement for improving skin health.

A separate study evaluated the effects of topical aloe vera oil and its combination with omega-3 fatty acids on skin health.⁷⁴ This study included 30 healthy Saudi female college students aged 18-25 years, who were randomly divided into two groups: one applied aloe vera oil alone, and the other applied a combination of aloe vera oil and omega-3 fatty acids in a 5:1 ratio. Both treatments were applied daily to the forearm for 30 days, with evaluations conducted at baseline, day 5, day 18, and day 31. Both groups demonstrated significant improvements in skin hardness and thickness over the study period compared to baseline. While the combination treatment showed slightly greater improvements, the differences between the groups were not statistically significant. The authors suggest a potential synergistic effect between aloe vera oil and omega-3 fatty acids, though larger, longer-term studies are needed to confirm these findings and explore the relationship further.

Overall, further research is needed to determine the full relationship between skin health and optimal doses of omega-3 supplementation. However, there is a clear beneficial relationship between increased omega-3 intake and the management of inflammation-related skin conditions.

Dosage Recommendation Based on Research

Both omega-6 and omega-3 fatty acids are necessary in the diet. However, omega-6 fatty acid metabolites include inflammatory compounds, and most western diets are significantly higher in omega-6 than omega-3 at a ratio of approximately 20:1.⁷⁵ For best health results, it is recommended to keep this ratio low, at about 4:1 or less. While there is currently no research-based specific recommendation of omega-3 dose to support skin health, general maintenance is a good place to begin. The current RDAs for ALA are 1.6 g per day for men, and 1.1 g per day for women. Women who are pregnant or lactating may require higher doses. While literature demonstrates that higher doses of omega-3s can have positive effects on skin health with limited risks to safety, a physician should be consulted before attempting such a regimen. Because EPA and DHA are more bioavailable, the recommendation for these is lower at 250-500 mg per day for both men and women. There is no established RDA or upper limit for docosapentaenoic acid (DPA), which is an intermediate between EPA and DHA.⁷⁶

Facts and Misconceptions

Omega-3’s have been shown to improve certain dermatological skin conditions, however, this does not mean that it will cure all skin problems. While omega-3 fatty acids support skin health by maintaining the skin barrier, they may be most helpful for those with inflammatory conditions such as acne or dermatitis, and potentially for the reduction of UV-related skin damage and cancers.

Food Sources

Omega-3 fatty acids are found primarily in fatty fish, as well as nuts and seeds. Fish contain DHA and EPA, the active forms of omega-3, while plant-based sources contain ALA which must be metabolized by the body into DHA and EPA. However, this conversion rate is low.⁷⁷ Therefore, for those who do not have dietary restrictions, fish are recommended as the primary source of omega-3s.

Plant sources high in Omega-3 Fatty Acids:

• Flaxseed oil – 7.26 g ALA per 1 tablespoon serving

• Flax seeds – 2.35 g ALA per 1 tablespoon serving

• Chia seeds – 5.06 g ALA per 1 oz serving

• Black walnuts – 0.76 g ALA per 1 oz serving

• Edamame – 0.28 g ALA per ½ cup serving

• Canola oil – 1.28 g ALA per 1 tablespoon serving

• Soybean oil – 0.92 g ALA per 1 tablespoon serving

Animal sources high in Omega-3 Fatty Acids:

• Mackerel (cooked) – 0.59 g DHA and 0.43 g EPA per 3 oz serving

• Salmon (farmed, cooked) – 1.24 g DHA and 0.59 g EPA per 3 oz serving

• Sardines (canned) – 0.74 g DHA and 0.45 g EPA per 3 oz serving

• Herring (cooked) – 0.94 g DHA and 0.77 g EPA per 3 oz serving

• Rainbow trout (wild, cooked) – 0.44 g DHA and 0.40 g EPA per 3 oz serving

• Tuna (canned) – 0.17 g DHA and 0.02 g EPA per 3 oz serving

Supplemental Sources

Omega-3 supplements are easily found OTC in the form of capsules, soft gels, and liquids. These products may be obtained from a variety of sources, including fish oil, flax oil, and algal oil. Fish oil contains both EPA and DHA, which are the active forms of omega-3. Flax oil is a good alternative for those on a vegetarian or vegan diet, but contains only ALA which has limited conversion to EPA and DHA in the body.⁷⁸ Algal oil contains both EPA and DHA, making it the best source of omega-3 for vegans and vegetarians. Omega-3 supplements are available in both natural and synthetic forms. While natural omega-3 supplements in triglyceride or phospholipid forms are generally well-absorbed, certain processed forms like re-esterified triglycerides may offer superior bioavailability.⁷⁹ Synthetic supplements often involve processing that converts omega-3s into ethyl ester forms. These ethyl esters are less efficiently absorbed compared to the natural forms. However, plant-based sources like flaxseed oil, despite being natural, may not provide the same levels of bioavailable EPA and DHA due to limited conversion in the body.⁸⁰

Side Effects

Omega-3 supplements are generally regarded as safe, with adverse events reported as mild, including: unpleasant taste, bad breath, heartburn, nausea, gastrointestinal discomfort, diarrhea, and headache.⁸¹ Omega-3 supplements may interact with anticoagulants like Warfarin.

Legal Status and Availability

Supplements containing omega-3 fatty acids are widely available OTC at lower doses, but may be available by physician prescription at higher therapeutic doses. As a dietary supplement, they are not subject to the same regulations as pharmaceuticals.

Bottom Line

Omega-3 fatty acids are an essential part of a healthy diet, and research indicates that the anti-inflammatory properties of omega-3s are useful in preventing and managing certain skin conditions such as acne and dermatitis. Omega-3s are found in their most bioactive form (EPA and DHA) in fatty fish such as salmon and mackerel, but can also be obtained from the ALA found in plant-based sources such as flax or chia seeds with a low rate of conversion. Supplements containing omega-3s are widely available, including fish oil, flaxseed oil, and algal oil, and are generally regarded as safe within the recommended doses. Adverse effects due to omega-3s are rare and usually mild, however they may interact with certain medications such as anticoagulants, and so a physician should be consulted by those who are on certain medications or have health concerns.

Specific Nutrient: Polyphenols

What is it

Polyphenols are a class of organic compounds that are found in plants that have antioxidant and anti-inflammatory properties. The most common sub-class of polyphenols are flavonoids, which are further broken down based on their chemical structure into flavonols, flavones, flavan-3-ols, flavanones, anthocyanins, and isoflavones. These compounds are found in a variety of natural sources including fruits, vegetables, and even teas, wine, and dark chocolate. In addition to their antioxidant and anti-inflammatory benefits, these compounds have also been shown to support heart health, boost brain function, and improve skin quality.⁸²

How it works

Polyphenols are plant-based compounds that affect the body in various ways. First and foremost, they are antioxidants that can neutralize free radicals which would otherwise break down collagen and DNA in the skin.⁸³ In addition to their effect as antioxidants, polyphenols are also capable of suppressing pro-inflammatory cytokines and enzymes which relieves the negative effects of inflammation on the appearance of skin.⁸⁴ While the mechanism is unclear, polyphenols from artichokes have been shown to inhibit vascular aging, which improves skin elasticity and roughness.⁸⁵ In the same vein, polyphenols demonstrate evidence of anti-aging effects in a variety of ways, such as decreasing collagen degradation, increasing collagen production, exhibiting antimicrobial activity and photoprotective effects, repairing DNA, reducing elastase activity, and eliminating senescent cells.⁸⁶ These compounds also have an impact on gut microbiota, which has additional benefits to human health. Polyphenols not only promote the growth of beneficial bacteria such as Lactobacillus and Bifidobacterium, but also inhibit the growth of harmful bacteria like Clostridium.⁸⁷ These effects on the gut microbiome in turn may impart anti-inflammatory and anti-cancer effects, and play a role in cardiovascular and metabolic health.⁸⁸

What the Research is Telling us

There are a number of clinical and in vitro studies demonstrating beneficial effects of consuming polyphenolic compounds, including their use for skin health. A small study investigating the effects of apple polyphenol supplementation on UV-induced pigmentation was conducted with 65 subjects aged 20-39 years.⁸⁹ In this double-blind trial, the participants were randomly assigned to receive either 300 or 600 mg per day of apple phenol, or a placebo for the 12 week duration. At the conclusion of the study, it was found that polyphenol supplementation significantly prevented UV-induced skin pigmentation, which is a key factor contributing to uneven skin tone, premature aging, and skin damage.

Another recent small study was conducted with 22 women to investigate the effect of a polyphenol-rich cranberry beverage on skin health.⁹⁰ This study utilized a randomized, double-blind, placebo-controlled crossover design, in which the participants were randomly assigned either the cranberry beverage or placebo for six weeks. The cranberry beverage contained 192.9 ± 1.5 mg of procyanidins, 19.5 mg anthocyanins, and 24.2 mg of flavonols per bottle. After the initial 6 week period, the participants underwent a 21-day washout, then consumed the opposite beverage for another six weeks. It was observed the consumption of the cranberry beverage significantly reduced a variety of factors, including UVB-induced erythema, net and gross forearm elasticity, and elasticity and smoothness of the face; these effects were observed predominantly in women over 40 years of age. Additionally, when compared to the placebo, the cranberry beverage was observed to result in improved oxidative stress and altered the abundance of several skin microbes.

As part of a larger review, one study evaluated a subgroup of 4 trials with a total of 248 participants that investigated procyanidin, a flavonoid common in many foods like apples and cranberries, and skin health.⁹¹ This analysis concluded that procyanidin had a significant effect on improving the water content in the stratum corneum of the skin when compared to a placebo (Standard Mean Difference (SMD) = 0.50, 95% CI = 0.15 – 0.86, P = 0.005). The authors note that a similar trend was observed when the analysis was extended to 9 trials (495 participants total), however these studies were heterogeneous, indicating a need for additional studies to verify the effect of polyphenolic compounds on skin moisture content.

A small randomized controlled trial investigated the effects of green tea polyphenols on various skin characteristics, including UV sensitivity, skin structure, hydration, and blood flow.⁹² The study involved 60 women aged 40–65, who were randomly assigned to either a control group receiving a placebo beverage or a test group consuming 1 L of a green tea beverage daily for 12 weeks. The green tea beverage contained 1402 mg of catechins, including epigallocatechin gallate (EGCG) and epicatechin. The results showed a 25% reduction in UV-induced erythema (P < 0.05) in the test group, along with a 4% increase in skin elasticity (P < 0.05), an 8% increase in skin density, and a 16% reduction in roughness (P < 0.05). Additionally, skin barrier function improved, as indicated by a 17% increase in hydration and a 12% decrease in transepidermal water loss.

The current body of clinical literature indicates that polyphenols are likely useful for improving the appearance of skin. However, these studies include a limited number of participants, and so the field would benefit from larger and more extensive studies in order to confirm these results and establish effective dosing and safety.

Dosage Recommendation Based on Research

Due to the complexity of their bioavailability and variability in dietary sources, there are currently no established recommended daily allowance (RDA) for polyphenolic compounds. One systematic review from Italy reported an approximate average intake of ~900 mg per day of polyphenols.⁹³ However, there are many variables that play into a potential recommended dose of polyphenols. First, different polyphenolic compounds may have varying bioavailabilities or mechanisms of actions. The availability of dietary sources may also vary widely between regions, further impacting regular and sustained consumption. Additionally, polyphenols have been shown to impact gut microbiota, which in turn may affect the bioavailability and metabolism of the polyphenols. A recent review found that total daily polyphenol intake varied from a mean of 458.8 ± 337.61 mg per day by Brazilian people aged 20 to 59, to 1,740 ± 630.2 mg per day among Polish people aged 45 to 69 years.⁹⁴ The mean American total daily phenolic intake was 1,666.3 ± 41.7 mg per day. While these values are not enough to inform on specific guidance, they do indicate that higher phenolic intakes from dietary sources up to approximately 2000 mg per day are likely not harmful. However, excessive intake from supplemental sources may be detrimental: high doses (10-29 mg/kg bodyweight per day) of polyphenol enriched green tea supplements have been shown to induce hepatotoxicity in humans.⁹⁵ Additionally, some animal studies have shown that high doses of some polyphenols may have carcinogenic or genotoxic effects.⁹⁶ Children and pregnant women should be particularly cautious about supplementation, with consultation from a medical professional.

Table 3 Dosage Recommendation for Polyphenols

Facts and Misconceptions

While polyphenols are widely accessible through the diet, they are not readily bioavailable and effective at the concentrations found in foods. These compounds must undergo significant metabolism in the body, and therefore not as bioavailable. For this reason, it is difficult to consume a harmful dose of polyphenols from natural dietary sources. While polyphenols are useful for a variety of functions, they do not all provide uniform health benefits. Their benefits can vary widely based on the subtype of compound, the food matrix, and genetic factors.⁹⁸

Food Sources

While the foods listed here all contain polyphenols, the specific type of compound that they contain may differ. For example, the primary polyphenol in green tea is epigallocatechin-3-gallate (EGCG), which is a flavan-3-ol, a subgroup of flavonoids. In contrast, red wine contains resveratrol, proanthocyanidins, and anthocyanins; resveratrol is a stilbenoid, while the proanthocyanidins and anthocyanins are flavonoids. While these compounds vary in their chemical structure and mechanism in the body, they are all beneficial for supporting overall health. For skin health in particular, you may consider enriching your diet with foods high in catechins (green tea), resveratrol (red wine, red grapes), and ellagic acid (pomegranates, raspberries, strawberries).

Plant sources high in Polyphenols:

• Dark Chocolate – 1,000 – 1500 mg per 100 g*

• Black elderberries – 1,350 mg per 100 g

• Blueberries – 560 mg per 100 g

• Pomegranates – 250 mg per 100 g

• Red onions – 168 mg per 100 g

• Artichokes – 260 mg per 100 g

• Green tea – 100 – 150 mg per 100 ml

• Black tea – 80 – 120 mg per 100 ml

• Coffee – ~ 200 mg per 100 ml

• Red wine – 100 – 150 mg per 100 ml

* Dark chocolate should be 70% or greater cacao

Specifically for skin health, consumption of some polyphenols are more beneficial than others.⁹⁹ These nutrients will take in the range of 4-12 weeks to begin showing benefits. Those which are beneficial for skin health include:

• Epigallocatechin Gallate (EGCG)

  • Found in green tea and matcha

  • EGCG protects skin from UV-induced oxidative damage, reduces collagen breakdown, and supports skin barrier repair.

• Resveratrol

  • Found in red wine, red grapes, and blueberries

  • Resveratrol activates sirtuins which reduce the signs of aging such as fine lines and wrinkles, and protects against UV-induced oxidative damage.

• Proanthocyanidins

  • Found in grape seeds, cranberries, apples, and cocoa

  • Proanthocyanidins improve collagen synthesis and skin elasticity, and prevent oxidative damage through the neutralization of free radicals.

• Cocoa Flavanols

  • Found in dark chocolate (>70% cocoa) and cocoa powder

  • Cocoa flavanols increase nitric oxide production, which improves hydration, texture, and blood flow leading to glowing skin.

• Quercetin

  • Found in onions, apples, grapes, citrus fruits, berries, and leafy greens

  • Quercetin is anti-inflammatory and protects against UV-induced oxidative damage, and also improves skin barrier function and hydration.

• Ellagic Acid

  • Found in pomegranates, raspberries, strawberries, and walnuts

  • Ellagic acid is anti-inflammatory and protects against collagen breakdown, promoting brighter firmer skin.

Supplemental Sources

Polyphenol supplements can be easily found in health food stores, pharmacies and online. Common supplements which are useful for skin health are EGCG green tea extract, resveratrol, curcumin, and grape seed extract, and can be found in the form of capsules or tablets, powders, and liquid extracts. While both natural and synthetic polyphenol supplements offer potential health benefits, their effectiveness is often limited by low bioavailability.¹⁰⁰ Because polyphenols often have low bioavailability, they sometimes include additives to enhance absorption; research to enhance bioavailability of these compounds is ongoing, including the use of nanocarriers.¹⁰¹ High doses (10-29 mg/kg bodyweight per day) of polyphenol enriched green tea supplements have been shown to induce hepatotoxicity, so it is best to consult a physician before beginning supplementation.¹⁰²

Side Effects

While the consumption of polyphenols in the diet is generally considered to be safe, care should be taken with concentrated supplemental sources, as excessive consumption (10-29 mg/kg bodyweight per day) may lead to an increased risk of side effects. These potential side effects include digestive issues, deficiencies in certain minerals, and liver toxicity.¹⁰³ Additionally, some polyphenols may have interactions with certain medications. Some notable potential interactions include resveratrol and curcumin with blood thinners, which can increase the risk of bleeding, and green tea extract, which may reduce the efficacy or absorption of blood pressure medications and beta-blockers.¹⁰⁴

Legal Status and Availability

Polyphenol supplements are generally considered to be food or dietary supplements. In the United States they must meet safety requirements and are not permitted to make health claims, but are freely available. In many other countries these products are subject to evaluation of efficacy claims as well, so they are more closely regulated but still available to the public.

Bottom Line

When obtained from dietary sources, polyphenols are highly beneficial compounds that may aid in a variety of health conditions, including cardiovascular and skin health. While polyphenol supplements are regulated for safety, care should be taken with high doses of concentrated supplemental products. Polyphenols can be obtained in the diet through a number of commonly consumed foods and beverages, including teas, coffee, wine, blueberries, and dark chocolate.

Specific Nutrient: Zinc, Copper, and Magnesium

What is it

Copper, zinc, and magnesium are essential dietary minerals that play crucial roles in numerous physiological processes in the human body. Copper is a key component of various enzymes and proteins, zinc is essential for growth, development, and immune function, and magnesium is fundamental to cellular and metabolic functions. These minerals also contribute significantly to maintaining skin elasticity by supporting collagen and elastin production, enhancing antioxidant defense, and sustaining cellular energy metabolism.¹⁰⁵ Adequate dietary intake of copper, zinc, and magnesium helps prevent premature aging, improve skin texture, and promote a youthful appearance.

How it works

Zinc is essential for maintaining healthy, elastic skin through multiple mechanisms. As an antioxidant, it reduces oxidative stress by neutralizing free radicals, which can lead to premature aging and diminished skin elasticity.¹⁰⁶ Zinc also serves as a cofactor for enzymes like prolyl hydroxylase, crucial for hydroxylating proline residues in collagen. This process ensures the stability and proper formation of the collagen triple-helix structure, which supports skin strength and flexibility.¹⁰⁷ Additionally, its anti-inflammatory properties help reduce redness and swelling, promoting smoother and more resilient skin.¹⁰⁸

Copper plays a pivotal role in enhancing skin elasticity and structure. It supports the cross-linking of collagen and elastin fibers by acting as a cofactor for lysyl oxidase, an enzyme vital for strengthening the extracellular matrix.¹⁰⁹ This cross-linking helps maintain skin firmness and minimizes signs of sagging and wrinkles. Copper also contributes to antioxidant defenses as a cofactor for superoxide dismutase, protecting collagen and elastin from oxidative damage caused by reactive oxygen species (ROS).¹¹⁰ Furthermore, copper aids in melanin production, shielding collagen from UV damage and supporting overall skin health.¹¹¹

Magnesium contributes significantly to skin health through its involvement in essential cellular functions. It supports protein and DNA synthesis, necessary for skin repair and renewal, and regulates enzymes critical for collagen production, helping to maintain the skin’s structural integrity.¹¹² Magnesium’s anti-inflammatory effects reduce skin irritation, which can impair elasticity and texture.¹¹³ Additionally, it promotes hydration by fortifying the skin’s lipid barrier and provides antioxidant protection against free radicals.¹¹⁴ Magnesium also stabilizes integrin-collagen interactions, crucial for collagen binding and cellular adhesion, ensuring skin remains supple and firm.¹¹⁵

What the Research is Telling us

The role of essential minerals such as zinc, magnesium, and copper in stimulating collagen production and maintaining skin health often involves indirect mechanisms, such as serving as cofactors for enzymatic processes. Consequently, there tends to be few clinical studies that isolate the individual impact of these dietary components on skin health, particularly for magnesium and copper. However, the impact of abnormal levels of these nutrients on skin health is more commonly evaluated.

Magnesium

An animal study examined the effects of magnesium deficiency in sexually mature rats.¹¹⁶ Previous research had established that young rats deprived of magnesium exhibit symptoms such as vasodilatation, hyperemia, and severe nutritional decline. However, the impact of magnesium deficiency on older rats remained uncertain. The researchers found that while vasodilatation and hyperemia were delayed and less pronounced in mature rats, they eventually developed skin lesions, including erythema, purpural hemorrhages (small purple or red spots on the skin), and eschars (dead tissue on wounds). When magnesium was reintroduced to their diet, the rats showed rapid recovery, with skin lesions healing and hair regrowth observed within days.

Another study examined magnesium levels in the epidermis, dermis, and whole skin of individuals with atopic dermatitis compared to normal subjects.¹¹⁷ Previous research had suggested that magnesium deficiency might be linked to atopic dermatitis, but findings were inconsistent. To clarify this, microincineration and fluorometric analyses were conducted on skin samples from both groups. The results showed no significant difference in epidermal magnesium levels between normal and atopic skin. However, magnesium levels were significantly higher in the dermis and whole skin of atopic subjects. This study suggests that rather than a deficiency, atopic skin may have altered magnesium utilization or a different balance between free and bound magnesium. These findings challenge the idea that atopic dermatitis is associated with a straightforward magnesium deficiency, and highlight the need for further research into magnesium’s role in skin conditions.

Similarly, one systematic review examined the role of various micronutrients, including magnesium, in atopic dermatitis (AD).¹¹⁸ While vitamins D, C, and E showed varying degrees of association with AD, the role of trace minerals like magnesium remains less clear. Studies indicate that serum magnesium levels are significantly lower in children with AD compared to healthy controls. The exact mechanism by which magnesium influences AD is not well understood, but it is known to play a role in cell proliferation, differentiation, and inflammatory responses. Overall, while magnesium may have some impact on AD, further research is needed to determine its precise role and the potential benefits of supplementation

While there is little research on the effect of dietary magnesium on skin health, clinical studies do support its topical use. A clinical study investigating the effects of bathing in a magnesium-rich Dead Sea salt solution demonstrated significant improvements in skin barrier function, hydration, roughness, and inflammation in individuals with atopic dry skin.¹¹⁹ In a double-blind, randomized design, 30 participants aged 20–54 years immersed one forearm in a 5% Dead Sea salt solution daily for six weeks, while the other forearm served as a control and was immersed in tap water. The study found that for participants with elevated transepidermal water loss (TEWL) at baseline, these levels decreased by 19% after 6 weeks (P < 0.05) indicating increased skin hydration. Additionally, a 40% reduction in skin roughness was observed (P < 0.05), as well as a significant reduction in skin redness (P < 0.05).

Similarly, in an animal study on 100 adult male Sprague Dweley rats, topical magnesium was observed to be effective in healing burn wounds.¹²⁰ The rats were divided into five groups: a positive control in which burns were induced with no treatment, a vehicle control of daily Eucerin cream on burns, a comparative control of an induced burn treated daily with Alpha burn cream, and two daily treatment groups of 2% or 4% MgSO₄ cream. A significant decrease in wound size was observed, with the 4% MgSO₄ group showing the smallest wound area (1.93 ± 0.51 cm²) compared to the untreated control (4.48 ± 0.92 cm², P < 0.05). Fibroblast density and blood vessel formation was seen to increase significantly (P < 0.001), indicating enhanced tissue repair, while skin tensile strength was 1.86–1.84 times greater in Mg-treated groups than in controls (P < 0.0001), indicating improved biomechanical properties. Additionally, inflammatory markers were also significantly reduced: Malondialdehyde (a biomarker of oxidative stress and lipid peroxidation) levels decreased from 15.44 ± 5.98 M/L in controls to 8.69 ± 2.25 M/L in the 2% Mg group (P < 0.001). Similarly, TNF-α (a pro-inflammatory cytokine) levels dropped from 1.61 ± 0.53 µg/mL to 1.06 ± 0.26 µg/mL (P < 0.001). Histological analysis confirmed increased collagen volume and fibroblast activity, with the 4% MgSO₄ formulation showing the strongest effects. These findings suggest that topical magnesium sulfate significantly accelerates burn wound healing by promoting tissue regeneration, reducing oxidative stress, and enhancing skin strength, highlighting its potential as a therapeutic agent for wound care.

Copper

One review explored the roles of trace elements in dermatological conditions, with a particular focus on their involvement in skin physiology, inflammation, immune function, and oxidative stress.¹²¹ Among these elements, copper plays a significant role in disease progression, particularly in conditions such as psoriasis and seborrheic dermatitis. In psoriasis, most studies report elevated serum copper levels, which correlate with disease severity as measured by the Psoriasis Area and Severity Index (PASI). This suggests that copper may contribute to the inflammatory processes underlying the disease. Similarly, patients with seborrheic dermatitis tend to have higher copper levels, indicating a possible link between copper dysregulation and disease progression. However, findings for other skin conditions are more variable. In atopic dermatitis, some studies suggest increased serum copper levels, while others find no significant difference compared to healthy controls. The role of copper in acne vulgaris is even less clear, with conflicting reports of both decreased and unchanged serum copper levels in affected individuals. More standardized, large-scale clinical studies are necessary to fully understand copper’s impact on skin diseases and its potential therapeutic implications.

One case report described two patients who developed acquired perforating dermatosis (APD) due to severe copper deficiency.¹²² APD is a rare skin condition that causes itchy, rough bumps and leads to the removal of skin components through the outer layer. Both patients had a history of gastric bypass surgery and chronic anemia, with lab tests revealing significantly low copper and ceruloplasmin levels. Following copper supplementation, their APD resolved completely, along with improvements in hematologic and neurologic symptoms. Given copper’s role in extracellular matrix maintenance, its deficiency may contribute to APD development. This case study illustrates the potential of copper deficiency to contribute to impaired skin health.

Regarding the use of oral copper supplementation as a therapeutic, a pilot study investigated the effects of increased copper intake on oxidant stress and collagen crosslinking.¹²³ This double-blind study involved 16 healthy women aged 18–24, who were randomized to receive 2 mg of copper glycinate daily or a placebo for eight weeks. Copper supplementation significantly increased the ratio of deoxypyridinoline (DPD, a biomarker of collagen degradation) crosslinks to collagen alpha-helical peptides by 62% (P < 0.05), indicating enhanced collagen stability. However, absolute levels of DPD or alpha-helical peptides did not change significantly, suggesting that copper’s role in collagen crosslinking needs further exploration through larger, more robust studies.

Taken together, these studies indicate that maintaining proper levels of the trace nutrient copper are important for maintaining healthy skin, as both excess and decreased copper levels can contribute to problems. Furthermore, copper supplementation may improve collagen stability, although further large confirmatory studies are needed to confirm this.

Zinc

A narrative review examined the association between serum zinc levels and various dermatological conditions by analyzing 48 studies published between 2017 and 2021.¹²⁴ This review highlighted significant associations between zinc deficiency and multiple skin disorders, with 33 out of 48 studies reporting statistically significant differences in zinc levels between affected patients and controls. With respect to psoriasis, studies indicated lower serum zinc levels across mild, moderate, and severe cases, with some research suggesting an increased copper/zinc ratio, indicative of oxidative stress and inflammation. Similarly, atopic dermatitis was correlated with zinc deficiency in three studies, which suggested that low zinc levels may impair skin barrier function and immune response, though one study found no association. Pityriasis alba was also linked to significantly lower zinc levels, with two studies reporting a 15-fold increased risk of developing the condition due to deficiency. Other skin conditions, including hidradenitis suppurativa, seborrheic dermatitis, and melasma, also demonstrated links to serum zinc levels, though with varying degrees of consistency. The review concluded that low serum zinc levels are associated with several chronic inflammatory skin conditions, including psoriasis, atopic dermatitis, alopecia, vitiligo, acne, and hidradenitis suppurativa, suggesting that zinc supplementation could serve as a cost-effective and low-risk adjunct therapy, particularly for autoimmune or inflammatory skin diseases. However, additional research is required to determine standardized treatment protocols and optimal dosing strategies for zinc supplementation.

Additionally, a systematic review evaluating the clinical efficacy of zinc supplementation for inflammatory skin conditions analyzed 22 studies involving 1,667 participants.¹²⁵ Zinc demonstrated significant benefits for acne vulgaris, improving lesion counts and reducing inflammation in 10 out of 14 studies, although it was less effective than antibiotics. Similarly, all three studies on hidradenitis suppurativa reported positive outcomes with reduced inflammation and lesion severity. Limited evidence supports zinc’s use for atopic dermatitis and diaper dermatitis, with mixed results, while no significant benefits were observed for psoriasis or rosacea. Various forms of zinc, including sulfate, gluconate, and oxide, were used at dosages ranging from 10 mg/day to 1.8 g/day, with gastrointestinal discomfort being the most common side effect. These findings suggest zinc to be a promising alternative or adjunct therapy for specific inflammatory skin conditions, particularly where long-term antibiotic or corticosteroid use is unsuitable.

While initial clinical evidence supports the potential roles of zinc, magnesium, and copper in influencing skin health, larger, more comprehensive studies are necessary to confirm their efficacy as standalone therapies, especially for magnesium and copper. The current body of research often examines these minerals as components of combination therapies, making it challenging to isolate their individual effects, especially as dietary components. Existing studies with direct clinical links to skin health are limited in scale and require validation in broader, more diverse populations. Despite the limitations in evaluating the effect of these mineral supplements on skin health in healthy populations, abnormal levels of zinc, copper, and magnesium are linked to negative impacts on the appearance of skin, and some studies indicate either oral or topical supplementation is suitable for improving skin conditions.

Dosage Recommendation Based on Research

The NIH recommends a daily intake of 900 micrograms of copper for both men and women, though higher doses are recommended for pregnant or lactating women.¹²⁶ A pilot study indicated that 2 mg daily of copper glycinate may enhance collagen stability.¹²⁷ Because this is well below the tolerable upper limit of copper, this dose is likely safe for improving skin elasticity.

The NIH recommends an RDA of 11 mg per day of zinc for men, and 8 mg per day for women, with higher doses suggested for women who are pregnant or lactating.¹²⁸ The tolerable upper limit of zinc is 40 mg per day. Plant-based sources of zinc contain compounds called phytates, which bind to zinc and inhibit its absorption; for this reason, the amount of zinc absorbed from dietary sources ranges from 5% to more than 50%. There is no specific daily intake recommendation for improving skin health through zinc consumption; meeting the RDA is likely sufficient for this purpose.

The NIH recommends 400 – 420 mg of magnesium per day for men based on age, with 400 mg recommended for age 19 – 30, and 420 recommended for age 31 and up.¹²⁹ For women, 310 mg per day is recommended for age 19 – 30, and 320 mg per day is recommended for age 31 and up; women who are pregnant or lactating may require higher intakes. Because the maximum daily allowance only considers magnesium obtained through supplementation, it is lower than the RDA for men; it does not take into consideration the amount obtained through food. There is no specific daily intake recommendation for improving skin health through magnesium consumption; meeting the RDA is likely sufficient for this purpose.

Table 4 Dosage Recommendation for zinc, copper, and magnesium

Facts and Misconceptions

Zinc, copper, and magnesium play essential roles in maintaining healthy skin elasticity, but their effects are often interconnected. Instead of acting alone, they work together with other nutrients to support overall skin health. While these minerals contribute to skin elasticity, they do not directly synthesize collagen. Instead, they aid in the proper functioning of enzymes necessary for collagen stabilization and other vital processes. It is important to note that supplementation is most beneficial when there is a deficiency. Excessive intake can lead to imbalances or potential toxicity, so care should be taken to ensure a well-balanced approach to supplementation.

Food Sources

Plant sources high in zinc:

• Pumpkin seeds (roasted) – 2.2 mg per 1 oz serving

• Turkey breast – 1.5 mg per 3 oz serving

• Lentils – 1.3 mg per ½ cup serving

• Peanuts (roasted) – 0.8 mg per 1 oz serving

Animal sources high in zinc:

• Oysters (Eastern, farmed, raw) – 32 mg per 3 oz serving

• Oysters (Pacific, cooked) – 28.2 mg per 3 oz serving

• Beef (bottom sirloin, roasted) – 3.8 mg per 3 oz serving

Plant sources high in copper:

• Shiitake mushrooms – 1.29 mg per 1 cup serving

• Cashews – 0.62 mg per 1 oz serving

• Sunflower seeds – 0.37 mg per 1 oz serving

• Lentils – 0.5 mg per 1 cup serving

• Black beans – 0.2 mg per 1 cup serving

Animal sources high in copper:

• Beef liver – 12 mg per 3 oz serving

• Lamb liver – 6 mg per 3 oz serving

• Oysters – 4.85 mg per 3 oz serving

• Lobster – 1.3 mg per 3 oz serving

• Crab – 0.9 mg per 3 oz serving

Plant sources high in magnesium:

• Pumpkin seeds (roasted) – 156 mg per 1 oz serving

• Chia seeds – 111 mg per 1 oz serving

• Almonds (dry roasted) – 80 mg per 1 oz serving

• Spinach (boiled) – 78 mg per ½ cup serving

• Cashews (dry roasted) – 63 mg per ¼ cup serving

• Black beans (cooked) – 60 mg per ½ cup

• Potato (baked, with skin) – 43 mg per 3.5 oz serving

Supplemental Sources

Zinc supplements are available in various forms, including zinc gluconate, zinc citrate, zinc sulfate, zinc picolinate, and zinc acetate. Among these, picolinate and citrate are generally better absorbed. Long-term use above the recommended daily intake can lead to copper deficiency due to interference with absorption.¹³⁰

Copper supplements are commonly formulated as copper gluconate, copper sulfate, and copper chelate, with copper bisglycinate chelate often providing superior absorption.

Magnesium supplements are also available in different forms, with magnesium citrate, glycinate, and malate typically offering the best absorption. For enhanced benefits, a multimineral supplement may be recommended, as their synergistic effects can optimize nutrient absorption and utilization.

Side Effects

Zinc, copper, and magnesium are generally safe and part of a healthy diet. However, overconsumption of these compounds may have adverse effects. Excess zinc intake can cause gastrointestinal discomfort, immune suppression, copper deficiency, lowered HDL cholesterol levels, and other symptoms such as headaches, fatigue, and lethargy. Zinc may also interact with certain medications such as antibiotics, penicillamine, and diuretics.¹³¹ Copper is not known to interact with any medications, but chronic, excessive consumption can result in gastrointestinal symptoms such as abdominal pain, cramps, nausea, diarrhea, and vomiting, and can also result in liver damage.¹³² Excess magnesium obtained through the diet is excreted through the urine, and so will not pose a risk; however, excess intake through supplements can result in diarrhea, nausea, abdominal cramping.¹³³ Very large doses of magnesium (>5,000 mg per day) are associated with magnesium toxicity, which may result in a variety of symptoms including hypotension, retention of urine, depression, lethargy, muscle weakness, difficulty breathing, irregular heartbeat, and cardiac arrest. Magnesium may also interact with certain medications such as antibiotics, diuretics, bisphosphonates, and proton pump inhibitors.

Legal Status and Availability

Copper, magnesium, and zinc supplements are commonly available as over-the-counter (OTC) dietary supplements in many countries. While standard doses can typically be purchased without a prescription, higher-dose formulations may require a prescription. These supplements are easily accessible at pharmacies, grocery stores, and online retailers, with strict regulations in place to ensure safety and accurate labeling.

Bottom Line

Zinc, copper, and magnesium are essential minerals that play important roles in supporting skin elasticity. Zinc helps promote collagen synthesis and protects skin cells from oxidative stress, while copper is critical for the cross-linking of collagen and elastin, ensuring skin’s structural integrity. Magnesium supports skin by facilitating the production of both collagen and elastin, and through its antioxidant and anti-inflammatory effects. Although clinical research directly linking these minerals to improved skin elasticity is limited, their supportive roles in skin health are well-established through in vitro studies. Current research suggests that these minerals should be incorporated into a balanced diet, as they contribute to the overall health of the extracellular matrix, enhance fibroblast function, and preserve collagen’s structural integrity.

Specific Nutrient: Aloe Vera

What is it

Aloe vera (Aloe barbadensis miller), a succulent plant valued for its medicinal, cosmetic, and therapeutic uses, has been a cornerstone of traditional medicine for centuries. The gel-like substance found within its leaves is a rich source of bioactive compounds that contribute to its wide range of health benefits. These include promoting skin repair and wound healing, enhancing digestive health, modulating immune responses, and showing potential anticancer and antidiabetic effects.¹³⁴ Aloe-based gels are especially popular for soothing mild sunburns, offering both a cooling effect and vital hydration for sun-damaged skin due to their high content of water and mucopolysaccharides.¹³⁵ They are also packed with antioxidants like vitamins C and E, which help to counter oxidative stress and preserve collagen and elastin.¹³⁶ In addition to topical applications, aloe vera has found a place in nutrition through aloe-based beverages, which provide a simple and refreshing way to obtain its benefits.

How it works

Aloe vera, when consumed as part of the diet, may improve skin health by boosting hydration, supporting collagen production, and reducing inflammation through its bioactive components. Ingested aloe vera gel has been shown to enhance the synthesis of collagen and hyaluronic acid, key molecules that maintain skin hydration and diminish the appearance of wrinkles.¹³⁷ By increasing hyaluronic acid levels, aloe vera helps the skin retain moisture, leading to a smoother and more youthful texture. Additionally, it prevents collagen breakdown by inhibiting the activity of enzymes like collagenase and metalloproteinases, which can degrade collagen fibers.¹³⁸ Aloe vera further supports the extracellular matrix by promoting collagen crosslinking, which strengthens skin structure and aids in wound repair.¹³⁹

Systemic inflammation plays a pivotal role in collagen and elastin degradation, contributing to reduced skin firmness and accelerated aging.¹⁴⁰ Aloe vera combats this by delivering anti-inflammatory effects through compounds such as C-glucosyl chromone, helping to protect the skin from inflammation-induced damage.¹⁴¹ Moreover, aloe vera is rich in antioxidants like vitamins C, E, and aloesin derivatives, which shield collagen and elastin from oxidative damage.¹⁴² These antioxidants not only prevent further degradation but also support the skin’s natural repair mechanisms, contributing to healthier, more resilient skin.

What the Research is Telling us

Clinical research on the effects of aloe vera for improving skin health remains limited in scope and sample size, but available studies suggest potential benefits even at low doses. A small randomized trial examined the impact of oral aloe vera gel supplementation on skin health.¹⁴³ The study involved 30 healthy women aged 49-74 years, divided into two groups: one receiving a low dose (1,200 mg/day) and the other a high dose (3,600 mg/day) of aloe vera gel for 90 days. Both groups experienced significant improvements in facial wrinkles and skin elasticity (P < 0.05). Additionally, both groups showed a significant increase in type I procollagen mRNA levels (P < 0.05), while the high-dose group also exhibited a significant reduction in MMP-1 mRNA levels (P < 0.05), indicating enhanced collagen synthesis and reduced collagen degradation. Despite the study’s small sample size and absence of a placebo group, it highlights aloe vera’s potential to improve skin elasticity and reduce wrinkles through its effects on collagen metabolism.

In a separate randomized, double-blind, placebo-controlled study, researchers assessed the effects of aloe sterol, a plant-based compound similar in structure to cholesterol, on skin health in 64 healthy Japanese women aged 30-59 years.¹⁴⁴ Participants in the treatment group consumed 40 micrograms of aloe sterol in yogurt daily, while the control group received a placebo. The treatment group demonstrated significantly improved skin hydration compared to the placebo group throughout the study (P < 0.001), even as seasonal humidity changes reduced hydration levels in the placebo group. Transepidermal water loss was significantly lower in the treatment group at weeks 4 and 12 (P = 0.039 and P = 0.001, respectively), reflecting enhanced skin barrier integrity. Improvements in skin elasticity, reduced skin fatigue, and increased collagen content in the dermis were also observed in the treatment group at all time points (P < 0.001). A follow up study evaluated the effects of a lower dose of daily oral aloe sterol on skin health.¹⁴⁵ In this study, 120 healthy Japanese women aged 30-55 years were randomized into a placebo group and a treatment group receiving 19 micrograms of aloe sterol daily for 12 weeks. The aloe sterol group exhibited significantly reduced transepidermal water loss compared to the placebo group (P = 0.0090), indicating enhanced skin barrier function. Dermal collagen content also increased significantly in the treatment group (P = 0.0291). Although no overall difference in hydration was observed between groups, subgroup analysis revealed significantly higher hydration levels in participants with dry skin in the aloe group at week 12 (P = 0.0415).

One animal study explored the protective effects of oral aloe vera gel powder (AVGP) on UVB-induced skin photoaging in hairless mice.¹⁴⁶ Female hairless mice were divided into three groups: a UVB control which received no treatment, a UVB group which received AVGP as 0.3% in the diet, and a UVB negative control. Results showed that UVB exposure significantly reduced skin elasticity, with an increase in skin viscosity and extracellular matrix degradation. However, supplementation with AVGP significantly preserved skin elasticity (P < 0.001) by reducing expression of MMP-13, a matrix metalloproteinase, by 39% (P < 0.05) and maintaining hyaluronic acid levels (P < 0.05). Additionally, AVGP prevented UVB-induced downregulation of Has2 gene expression, which is crucial for hyaluronic acid synthesis, and significantly restored serum adiponectin levels, a hormone which influences collagen and hyaluronic acid production (P < 0.05). These findings suggest that oral aloe vera supplementation may be a promising therapy for maintaining skin elasticity and preventing UV-induced skin aging.

While larger and longer-term studies are needed, these findings support dietary aloe vera as a safe and effective supplement for improving collagen production, skin hydration, and overall skin health.

Dosage Recommendation Based on Research

There is no well-established daily intake for the use of aloe to improve skin health, although clinical research indicates that 1,200 – 3,600 mg of aloe gel per day or 20 – 40 micrograms of aloe sterol per day are both effective and well tolerated.¹⁴⁷ The upper tolerable safe limit of aloe in humans is not well established; however, a mouse study estimated that, adjusted for safety and modifying factors, the upper limit for humans is 0.4 mg per kg of bodyweight per day of aloe gel.¹⁴⁸ Care should be taken to avoid products that contain aloe latex or its component, aloin, as these can be toxic and potentially carcinogenic.¹⁴⁹

Table 5 Dosage Recommendation for Aloe Vera

Facts and Misconceptions

The most common misconception about aloe is that it is only useful externally as a topical treatment for sunburn. However, research shows that orally ingested aloe products may be useful for promoting skin repair and wound healing, enhancing digestive health, modulating immune responses, and also show potential anticancer and antidiabetic effects.¹⁵⁰

Food Sources

The aloe vera plant, Aloe barbadensis miller, is the only natural source of aloe. However, the whole plant should never be consumed. The aloe vera leaf contains a green rind, a yellow latex layer, and a clear, jelly-like gel inside. The aloe gel can safely be consumed raw, however the latex layer is toxic, and ingesting 1 g per day for several days can cause acute kidney failure and result in death.¹⁵¹ The edible aloe gel can be added to smoothies, drinks, or desserts for consumption. Beverages containing aloe are popular in some grocery stores, and supplements are also easily found.

Supplemental Sources

Dietary aloe supplements are available in various forms such as aloe vera juice, gel capsules, tablets, softgels, powder, and liquid concentrates. Aloe vera juice is liquid that is extracted from the inner leaf gel of the plant, which is sometimes mixed with water or fruit juice. Gel capsules contain dried or freeze-dried gel powder, while tablets are made of compressed gel or powdered extract. The softgel formulations are gelatin capsules filled with liquid extract or gel. Aloe vera powder is a dehydrated, powdered aloe gel which is often mixed with other supplements or beverages. The liquid concentrates are highly concentrated aloe gel or juice, and can be diluted in water or taken directly. It is unclear whether one form of supplement is more effective than another for skin health, however aloe juice is likely the most accessible and commonly found option. Care should be taken to avoid supplements containing aloe latex, unless a strong laxative effect is desired, in which case caution should be exercised to observe the recommended dosage, and physician supervision is recommended due to its toxic potential.

Side Effects

Aloe vera is generally regarded as safe when consumed in appropriate amounts, particularly the gel. However, excessive consumption of aloe gel or the intake of aloe latex can cause side effects. Prolonged or high-dose use of aloe latex has been linked to kidney damage, gastrointestinal discomfort, electrolyte imbalance, and potential carcinogenicity.¹⁵² Aloe vera can also interact with certain medications, including laxatives, diuretics, antidiabetic drugs, and blood thinners, potentially altering their effects.¹⁵³ Pregnant and breastfeeding women are advised to avoid aloe consumption, as it may induce uterine contractions or impact nursing infants.¹⁵⁴

Legal Status and Availability

The legal status and availability of aloe supplements vary by country and product type. Common forms such as gels, juices, capsules, powders, and topical formulations are widely accessible, though regulations differ. In the United States, aloe supplements are readily available; however, the FDA banned latex-containing laxatives in 2002 due to safety concerns related to aloin’s potential carcinogenicity. Similarly, most other countries allow the sale of aloe supplements but impose restrictions on products containing latex. Aloe supplements are commonly found in health food stores, pharmacies, and through online retailers, making them accessible to consumers worldwide.

Bottom Line

Aloe vera holds potential for enhancing skin elasticity and overall skin health, both as a dietary supplement and a topical treatment. Fresh aloe can offer benefits, but it must be properly prepared to remove irritants such as aloin and latex. High-quality, processed aloe products are typically more concentrated, standardized, and safer for regular use. While aloe vera supports hydration, skin barrier repair, and collagen production, it is not a complete solution for reversing all signs of aging. Oral supplementation has demonstrated benefits such as reducing facial wrinkles, improving skin elasticity, and stimulating collagen production. Clinical studies have reported significant increases in type I procollagen levels and reductions in collagen-degrading enzymes, supporting aloe’s role in promoting skin health. Long-term enhancement of skin elasticity depends on internal collagen synthesis, which aloe vera supports indirectly through its bioactive components. Although the current clinical evidence is limited in size and scope, it strongly supports the use of oral aloe supplementation for improving skin elasticity. Further large-scale, placebo-controlled studies are necessary to confirm these findings and establish optimal dosage guidelines. Aloe vera is generally considered safe when latex and aloin-containing compounds are avoided, though it is not recommended for use by pregnant or breastfeeding women.

Dietary Strategy

Mediterranean Diet

The Mediterranean diet is a common dietary strategy which places heavy emphasis on the consumption of fruits, vegetables, whole grains, healthy fats, and lean proteins.¹⁵⁵ Mediterranean diets are generally regarded as one of the most beneficial diet types for cardiovascular health. A large randomized controlled trial of 7447 participants concluded that a Mediterranean diet supplemented with extra virgin olive oil or mixed nuts resulted in an approximate relative risk reduction of 30% for cardiovascular disease related events as compared to a low fat diet.¹⁵⁶ Because this diet is highly anti-inflammatory due to its high frequency of omega-3 fatty acids and antioxidants, it is recommended for improving skin health as well. In a prospective 16 week study, a plant-based Mediterranean diet supplemented with algae-derived omega-3s was shown to significantly improve both inflammatory and non-inflammatory acne lesions (P <0.001).¹⁵⁷

A typical Mediterranean diet includes the following:

• Vegetables such as spinach, kale, tomatoes, bell peppers, zucchini, cucumber, eggplant, and onions.

  • Provide sources of antioxidant vitamins and polyphenolic compounds

• Fruits such as oranges, apples, grapes, pomegranates, figs, and berries.

  • Provide sources of antioxidant vitamins and polyphenolic compounds

• Healthy fats such as extra virgin olive oil, walnuts, almonds, flax seeds, chia seeds, salmon, mackerel, sardines, and avocados.

  • Good sources of omega-3 fatty acids

• Lean proteins like fish and seafood, legumes, eggs, and poultry.

• Whole grains such as brown rice, quinoa, barley, and oats.

Anti-Inflammatory Diet

Similar to the Mediterranean diet is the anti-inflammatory diet. This diet focuses on increasing the abundance of foods which contain nutrients that reduce inflammation such as omega-3 fatty acids and antioxidants, while reducing those that are high in sugar, fried, or overly processed.¹⁵⁸ This diet is quite similar to the Mediterranean diet, but also incorporates spices like turmeric and ginger. A general plant-based diet is also beneficial for skin health as it also advocates for increased consumption of foods high in antioxidants and polyphenols.

Low Glycemic Diet

A low glycemic diet focuses on the consumption of foods which have a low glycemic index (GI), which are digested and absorbed by the body at a slower pace, leading to a more gradual increase in blood sugar levels.¹⁵⁹ Because this diet stabilizes blood sugar and prevents insulin spikes, it plays a role in moderating sebum production and acne and has a positive impact on skin health.¹⁶⁰ Additionally, the lower sugar levels due to a low GI diet reduce a process called glycation, in which sugar molecules link to collagen and elastin in the skin which leads to damaged skin.¹⁶¹ To adhere to a low GI diet, you should focus on whole foods, avoid highly processed and refined carbohydrates, and combine carbohydrates with fiber, protein, or healthy fats, which help to slow digestion and lower the glycemic impact.

Some examples of low glycemic index foods include the following:

• Grains: steel-cut oats, quinoa, barley

• Fruits: apples, berries, cherries, oranges

• Vegetables: leafy greens, carrots broccoli

• Legumes: lentils, chickpeas, black beans

• Dairy: Milk, unsweetened yogurt

Ketogenic Diet

Like the low-GI diet, the ketogenic, or keto, diet also reduces glycation and reduces blood sugar due to the very low level of carbohydrates that are consumed.¹⁶² Practitioners of the keto diet typically consume much higher amounts of protein and fats in order to make up for the lack of calories from carbohydrates. This diet is generally very rich in healthy fats like omega-3s, which are good for their anti-inflammatory and hydrating properties. However, due to the exclusion of carbohydrates, consumption of foods containing antioxidants and polyphenolic compounds may be lacking compared to other skin-beneficial diets.¹⁶³

A skin-centric keto diet may include the following foods:

• Fatty fish like salmon, sardines, and mackerel

  • High in omega-3 fatty acids

• Olive oil, flax seeds, chia seeds, walnuts, almonds, and avocados

  • High in omega-3 fatty acids

• Leafy greens like spinach and kale

  • Rich in antioxidants

• Bone broth

  • Provides collagen to improve skin elasticity

These various diets, including the Mediterranean diet, the anti-inflammatory diet, the low GI diet, or the keto diet, may improve skin health by reducing inflammation and increasing the amount of beneficial nutrients that are obtained through food. To find the best approach for your skin, it may be necessary to try different diets and monitor their effect.

The Role of Water

Maintaining proper hydration is also key for supporting skin health. Water is important not only for overall physiological processes, but also significantly impacts skin elasticity and appearance. Proper hydration leads to a reduction in wrinkles and improves its ability to function as an effective barrier against environmental stressors such as pollution, oxidative stress, and UV radiation.¹⁶⁴ Hydration improves barrier function by increasing the water continent in the stratum corneum, which is the outermost layer of skin. This layer relies on water to maintain the organization of the lipids within, which is essential for preventing transepidermal water loss.¹⁶⁵

The total amount of water necessary per day to improve the appearance and function of skin will vary based on factors such as age, activity level, and climate. For example, those who reside in hot, dry climates or are very active may require higher water intakes as they lose hydration through sweat. However, in general, men should aim for approximately 120 ounces per day, while women should aim for 90 ounces; these include intakes from water itself, as well as food and beverages.

While the obvious choice might be to reach for a glass of water, there are many fruits and vegetables which are high in water content and can be incorporated into the diet to improve hydration. Fruits which are high in water content include watermelon, strawberries, cantaloupe, peaches and oranges, while vegetables which are high in water content include cucumbers, iceberg lettuce, radishes, tomatoes, and spinach. Consuming fresh foods such as these will not only improve hydration, but provide other nutrients such as vitamins which can also aid in skin health for a multifunctional approach.

A Brief Note on Collagen

An important part of healthy, radiant skin is collagen. Collagen is the most abundant protein in the skin, and plays an essential role in maintaining its firmness and elasticity.¹⁶⁶ Collagen production naturally declines with age, leading to visible signs such as fine lines and wrinkles.¹⁶⁷ In addition to aging, environmental factors like UV exposure, pollution, and poor nutrition can further degrade collagen, which has a negative impact on the skin’s appearance. To maintain a radiant complexion, it is important to support collagen synthesis through a balanced diet and lifestyle choices. For a more in-depth exploration of collagen production, maintenance, and its dietary influences, please refer to Skin Elasticity and Collagen Production.

Who are the Experts

Dr. Jens J Thiele, MD, PhD, is an internationally renowned expert on oxidative stages and photocarcinogenics. Dr. Thiele obtained his medical degree from JW Goethe University in Germany, which was followed by an internship at The University of Chicago Hospital, dermatology residency at Boston University and Tufts University, and finally by a fellowship at the American College of Mohs Surgery. He has authored over 100 peer-reviewed publications, and currently accepts patients in the Oceanside, CA area through Dermatology Specialists, Inc. Additionally, he currently serves on the editorial boards of the International Journal of Cosmetic Science and the Open Dermatology Journal.

• Abstracts of relevant published works:

  • Vitamin E in human skin: organ-specific physiology and considerations for its use in dermatology¹⁶⁸ (Elsevier, September 2007)

  • Vitamin E: Critical Review of Its Current Use in Cosmetic and Clinical Dermatology¹⁶⁹ (Wolters Kluwer Health, March 2006)

Dr. Philip Calder, PhD, DPhil, RNutr, FRSB, FAfN, is an internationally recognized researcher, focusing on nutritional modulation of immunity, inflammation, and cardiometabolic disease risk. Dr. Calder obtained his PhD in biochemistry from the University of Auckland, and is hailed as a highly cited researcher, having authored over 800 peer-reviewed publications and four books. He is currently the Head of Human Development & Health and Professor of Nutritional Immunology within Medicine at the University of Southampton in the United Kingdom.

• Abstracts of relevant published works:

  • Conversion of Alpha-Linolenic Acid to Longer-Chain Polyunsaturated Fatty Acids in Human Adults¹⁷⁰ (Eco Sciences, April 2005)

  • Omega-3 Fatty Acids and Inflammatory Processes: From Molecules to Man¹⁷¹ (Portland Press, September 2017)

Dr. Lesley Rhodes, MD, FRCP, FRSB, is a Professor of Dermatology and Photobiology at the University of Manchester. Dr. Rhodes has more than 200 publications, including more than 150 research manuscripts in journals such as the New England Journal of Medicine and Nature Sustainability. Her research includes studying the sunlight-induced production of Vitamin D in humans and photoprotective measures against skin cancer and photosensitivity.

• Abstracts of relevant published works:

  • Effects of Oral Vitamin E and Beta-Carotene Supplementation on Ultraviolet Radiation-Induced Oxidative Stress in Human Skin¹⁷²(Elsevier, November 2004)

  • UVR-Induced Oxidative Stress in Human Skin in Vivo¹⁷³ (Elsevier, November 2002)

  • Effect of Eicosapentaenoic Acid, an Omega-3 Polyunsaturated Fatty Acid, on UVR-Related Cancer Risk in Humans. An Assessment of Early Genotoxic Markers¹⁷⁴ (Oxford University Press, May 2003)

Positions and Views of Worldwide Governmental Medical and Health Organizations

There is no formal guidance from the worldwide medical community on the maintenance of glowing and radiant skin. These sources focus on the management and prevention of skin-related ailments, such as psoriasis, dermatitis, and skin cancer.

Worldwide governmental websites largely do not provide information on the maintenance of healthy skin, rather focusing on disease states such as skin cancer, dermatitis, and psoriasis. The National Institutes for Health has some guidance for healthier skin as you age, and the relationship between skincare and aging:

• NIH – Tips for Healthier Skin as you Age

• NIH – Skincare and Aging.

Nonprofits and Private Organizations

Organizations dedicated to healthy skin:

• American Academy of Dermatology Association (AAD)

  • Purpose/ Mission Statement

    • “AAD is committed to: advancing the diagnosis and medical, surgical, and cosmetic treatment of the skin, hair, and nails; advocating high standards in clinical practice, education, and research in dermatology; and supporting and enhancing patient care for a lifetime of healthier skin, hair, and nails.” About AAD

  • Social Media Accounts:

    • Facebook // Twitter // Youtube

• Skin Cancer Foundation

  • Purpose/ Mission Statement

    • “The Skin Cancer Foundation saves and improves lives. We empower people to take a proactive approach to daily sun protection and the early detection and treatment of skin cancer.” About Skin Cancer Foundation

  • Social Media Accounts:

    • Facebook // Twitter

• International Alliance of Dermatology Patient Organizations (IADPO) (GlobalSkin)

  • Purpose/ Mission Statement

    • “The International Alliance of Dermatology Patient Organizations (also known as GlobalSkin) – is a unique global alliance serving patient organizations to improve the lives of dermatology patients worldwide.” About GlobalSkin

  • Social Media Accounts:

    • Facebook // Twitter // Youtube

• Acne and Rosacea Society of Canada

  • Purpose/ Mission Statement

    • “The Acne and Rosacea Society of Canada, a national, not for profit organization led by Canadian dermatologists, offers hope and help to sufferers by providing independent, reputable and current information on these conditions and raising awareness.” About the Acne and Rosacea Society of Canada

  • Social Media Accounts:

    • Facebook // Instagram

Social Media Contributors

• Social media communities dedicated to improving skin health through diet

  • Well Within Beauty – This blog provides a beauty nutrition guide to healthy skin, discussing the impact of various foods and nutrients on skin health.

    • Instagram (5.3K followers) // Facebook (31K followers)

  • Skin Health Foundation – This platform provides a variety of articles about skin health, including how diet impacts skin and promotes a healthy complexion.

• Social media influencers on improving skin health through diet

  • TikTok – @alicecsun (391.6K followers) – While she does not go into depth about many of the specific nutritional benefits, TikToker Alice Sun is a huge proponent of eating balanced meals to improve skin health based on the concept of traditional chinese medicine (TCM). Many of her dishes include healthy fats such as salmon and avocado and vegetables that are high in vitamins and polyphenols. While much of TCM is not well-supported by scientific literature, a diet rich in omega-3s, vitamins, and polyphenols supports overall health as well as the skin.

  • TikTok – HappySkinKitchen (85.6K followers) – HappySkinKitchen is a TikTok page run by Elisa Rossi, a content creator and author of a cookbook of the same name. Elisa focuses on the use of nutrition through a vegan, nutrient-dense diet to promote skincare, including a range of foods that include healthy fats, whole grains, and various fruits and vegetables. While she does not discuss in detail the specific role these nutrients play in skin health, it appears to be a good resource for new recipes to include as part of a balanced, skin-healthy diet.

Bibliography

Aatif, Mohammad. “Current Understanding of Polyphenols to Enhance Bioavailability for Better Therapies.” Biomedicines 11, no. 7 (July 24, 2023): 2078. https://doi.org/10.3390/biomedicines11072078.

Abadie, Mohammed Al, Zinah Sharara, Miriam Al Abadie, Patrick A. Ball, and Hana Morrissey. “Possible Relationship between Poor Skin Disorders Prognosis and Serum Zinc Level: A Narrative Review.” Dermatology Reports 14, no. 4 (July 6, 2022): 9512. https://doi.org/10.4081/dr.2022.9512.

Abdelhamid, Asmaa S., Tracey J. Brown, Julii S. Brainard, Priti Biswas, Gabrielle C. Thorpe, Helen J. Moore, Katherine HO Deane, et al. “Omega‐3 Fatty Acids for the Primary and Secondary Prevention of Cardiovascular Disease – Abdelhamid, AS – 2020 | Cochrane Library.” Accessed December 16, 2024. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD003177.pub5/full.

“Acne Can Affect More than Your Skin.” Accessed January 27, 2025. https://www.aad.org/public/diseases/acne/acne-emotional-effects.

Addor, Flavia, Juliana Cotta Vieira, and Camila Abreu. “Improvement of Dermal Parameters in Aged Skin after Oral Use of a Nutrient Supplement.” Clinical, Cosmetic and Investigational Dermatology Volume 11 (April 2018): 195–201. https://doi.org/10.2147/CCID.S150269.

Agrawal, Rashi, Anne Hu, and Wendy B. Bollag. “The Skin and Inflamm-Aging.” Biology 12, no. 11 (November 2, 2023): 1396. https://doi.org/10.3390/biology12111396.

Ahmed, Idris Adewale, and Maryam Abimbola Mikail. “Diet and Skin Health: The Good and the Bad.” Nutrition (Burbank, Los Angeles County, Calif.) 119 (March 2024): 112350. https://doi.org/10.1016/j.nut.2023.112350.

Alarim, Raghad A, Faris A Alasmre, Hammam A Alotaibi, Mohammed A Alshehri, and Sara A Hussain. “Effects of the Ketogenic Diet on Glycemic Control in Diabetic Patients: Meta-Analysis of Clinical Trials.” Cureus 12, no. 10 (n.d.): e10796. https://doi.org/10.7759/cureus.10796.

Alberts, D., J. Ranger-Moore, J. Einspahr, K. Saboda, P. Bozzo, Yun Liu, Xìao-chun Xu, et al. “Safety and Efficacy of Dose-Intensive Oral Vitamin A in Subjects with Sun-Damaged Skin.” Clinical Cancer Research 10 (2004): 1875–80. https://doi.org/10.1158/1078-0432.CCR-03-0188.

Alijani, Sepideh, Andreas Hahn, William S. Harris, and Jan Philipp Schuchardt. “Bioavailability of EPA and DHA in Humans – A Comprehensive Review.” Progress in Lipid Research 97 (January 1, 2025): 101318. https://doi.org/10.1016/j.plipres.2024.101318.

Al‐Niaimi, F., and N. Y. Chiang. “Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications.” The Journal of Clinical and Aesthetic Dermatology 10 7 (2017): 14–17.

Alrasheed, M., L. Hammad, A. Altaweel, Alaa Assiri, Albatool A. Bin Ajlan, Rawan A. Almugbel, Shaikha Aldukhail, N. Abanmy, and G. Shazly. “Improving Skin Hardness and Thickness Using a Combination of Omega-3 Fatty Acid and Aloe Vera Oil: Pilot Study” 3 (2020): 60–64. https://doi.org/10.21608/jabps.2020.21568.1065.

Altgilbers, Silke, F. Rippke, A. Filbry, Stefanie Conzelmann, J. Vietzke, T. Burkhardt, D. Segger, D. Roggenkamp, and E. Grönniger. “A Biomimetic Combination of Actives Enhances Skin Hydration and Barrier Function via Modulation of Gene Expression: Results of Two Double-Blind, Vehicle-Controlled Clinical Studies.” Skin Pharmacology and Physiology 35 (2021): 102–11. https://doi.org/10.1159/000520009.

Anderson, Breanne M, and David WL Ma. “Are All N-3 Polyunsaturated Fatty Acids Created Equal?” Lipids in Health and Disease 8 (August 10, 2009): 33. https://doi.org/10.1186/1476-511X-8-33.

Asbaghi, Omid, Mehdi Sadeghian, Behzad Nazarian, Mehrnoosh Sarreshtedari, Hassan Mozaffari-Khosravi, Vahid Maleki, Mohammad Alizadeh, Azad Shokri, and Omid Sadeghi. “The Effect of Vitamin E Supplementation on Selected Inflammatory Biomarkers in Adults: A Systematic Review and Meta-Analysis of Randomized Clinical Trials.” Scientific Reports 10 (October 14, 2020): 17234. https://doi.org/10.1038/s41598-020-73741-6.

Ashique, Sumel, Shubneesh Kumar, Afzal Hussain, Neeraj Mishra, Ashish Garg, B. H. Jaswanth Gowda, Arshad Farid, Gaurav Gupta, Kamal Dua, and Farzad Taghizadeh-Hesary. “A Narrative Review on the Role of Magnesium in Immune Regulation, Inflammation, Infectious Diseases, and Cancer.” Journal of Health, Population, and Nutrition 42 (July 27, 2023): 74. https://doi.org/10.1186/s41043-023-00423-0.

Barbosa, Eliana, Joel Faintuch, Emilia Addison Machado Moreira, Viviane Rodrigues Gonçalves da Silva, Maurício José Lopes Pereima, Regina Lúcia Martins Fagundes, and Danilo Wilhelm Filho. “Supplementation of Vitamin E, Vitamin C, and Zinc Attenuates Oxidative Stress in Burned Children: A Randomized, Double-Blind, Placebo-Controlled Pilot Study.” Journal of Burn Care & Research 30, no. 5 (September 1, 2009): 859–66. https://doi.org/10.1097/BCR.0b013e3181b487a8.

Barrantes, E., and M. Guinea. “Inhibition of Collagenase and Metalloproteinases by Aloins and Aloe Gel.” Life Sciences 72 7 (2003): 843–50. https://doi.org/10.1016/S0024-3205(02)02308-1.

Barron, G. P., P. B. Pearson, and S. O. Brown. “Magnesium Deficiency in the Sexually Mature Rat.” Proceedings of the Society for Experimental Biology and Medicine 69, no. 1 (October 1, 1948): 128–30. https://doi.org/10.3181/00379727-69-16639.

Beer, K., A. Singh, S. C. Ravi, A. K. Gupta, A. Kumar, and M. M. Sharma. “A Comprehensive Review on the Role of Vitamin A on Human Health and Nutrition.” Journal of Environmental Biology, 2024. https://doi.org/10.22438/jeb/45/6/mrn-5339.

Bertelli, A., M. Biagi, M. Corsini, G. Baini, Giorgio Cappellucci, and E. Miraldi. “Polyphenols: From Theory to Practice.” Foods 10 (2021). https://doi.org/10.3390/foods10112595.

Bo’, C. Del, S. Bernardi, M. Marino, M. Porrini, M. Tucci, S. Guglielmetti, A. Cherubini, et al. “Systematic Review on Polyphenol Intake and Health Outcomes: Is There Sufficient Evidence to Define a Health-Promoting Polyphenol-Rich Dietary Pattern?” Nutrients 11 (2019). https://doi.org/10.3390/nu11061355.

Burdge, Graham C., and Philip C. Calder. “Conversion of Alpha-Linolenic Acid to Longer-Chain Polyunsaturated Fatty Acids in Human Adults.” Reproduction, Nutrition, Development 45, no. 5 (2005): 581–97. https://doi.org/10.1051/rnd:2005047.

Calder, Philip C. “Omega-3 Fatty Acids and Inflammatory Processes: From Molecules to Man.” Biochemical Society Transactions 45, no. 5 (October 15, 2017): 1105–15. https://doi.org/10.1042/BST20160474.

Cao, Changwei, Zhichao Xiao, Yinglong Wu, and Changrong Ge. “Diet and Skin Aging—From the Perspective of Food Nutrition.” Nutrients 12, no. 3 (March 24, 2020): 870. https://doi.org/10.3390/nu12030870.

———. “Diet and Skin Aging—From the Perspective of Food Nutrition.” Nutrients 12, no. 3 (March 24, 2020): 870. https://doi.org/10.3390/nu12030870.

Carr, Anitra C., Stephanie M. Bozonet, Juliet M. Pullar, Jeremy W. Simcock, and Margreet C. M. Vissers. “A Randomized Steady-State Bioavailability Study of Synthetic versus Natural (Kiwifruit-Derived) Vitamin C.” Nutrients 5, no. 9 (September 17, 2013): 3684–95. https://doi.org/10.3390/nu5093684.

Cartolano, F., G. D. Dias, S. Miyamoto, and N. Damasceno. “Omega-3 Fatty Acids Improve Functionality of High-Density Lipoprotein in Individuals With High Cardiovascular Risk: A Randomized, Parallel, Controlled and Double-Blind Clinical Trial.” Frontiers in Nutrition 8 (2022). https://doi.org/10.3389/fnut.2021.767535.

Cheng, K., Y. Niu, X. C. Zheng, H. Zhang, Y. P. Chen, M. Zhang, X. X. Huang, L. L. Zhang, Y. M. Zhou, and T. Wang. “A Comparison of Natural (D-α-Tocopherol) and Synthetic (DL-α-Tocopherol Acetate) Vitamin E Supplementation on the Growth Performance, Meat Quality and Oxidative Status of Broilers.” Asian-Australasian Journal of Animal Sciences 29, no. 5 (May 2016): 681–88. https://doi.org/10.5713/ajas.15.0819.

Cho, Soyun, Serah Lee, Min-Jung Lee, Dong Hun Lee, Chong-Hyun Won, Sang Min Kim, and Jin Ho Chung. “Dietary Aloe Vera Supplementation Improves Facial Wrinkles and Elasticity and It Increases the Type I Procollagen Gene Expression in Human Skin in Vivo.” Annals of Dermatology 21, no. 1 (February 2009): 6–11. https://doi.org/10.5021/ad.2009.21.1.6.

Christman, L., Anna De Benedetto, Elizabeth Johnson, Christina Khoo, and Liwei Gu. “Polyphenol-Rich Cranberry Beverage Positively Affected Skin Health, Skin Lipids, Skin Microbiome, Inflammation, and Oxidative Stress in Women in a Randomized Controlled Trial.” Nutrients 16 (2024). https://doi.org/10.3390/nu16183126.

Cleveland Clinic. “Integumentary System: What It Is, Function & Organs.” Accessed March 18, 2025. https://my.clevelandclinic.org/health/body/22827-integumentary-system.

Cleveland Clinic. “What Is the Mediterranean Diet?” Accessed March 18, 2025. https://my.clevelandclinic.org/health/articles/16037-mediterranean-diet.

Cook, Madison K., Patrick O. Perche, and Steven R. Feldman. “The Use of Oral Vitamin A in Acne Management: A Review.” Dermatology Online Journal 28, no. 5 (October 15, 2022). https://doi.org/10.5070/D328559239.

Corrêa, T. A., M. Rogero, N. M. Hassimotto, and F. Lajolo. “The Two-Way Polyphenols-Microbiota Interactions and Their Effects on Obesity and Related Metabolic Diseases.” Frontiers in Nutrition 6 (2019). https://doi.org/10.3389/fnut.2019.00188.

Cosgrove, Maeve C, Oscar H Franco, Stewart P Granger, Peter G Murray, and Andrew E Mayes. “Dietary Nutrient Intakes and Skin-Aging Appearance among Middle-Aged American Women.” The American Journal of Clinical Nutrition 86, no. 4 (October 2007): 1225–31. https://doi.org/10.1093/ajcn/86.4.1225.

Crosby, Lee, Brenda Davis, Shivam Joshi, Meghan Jardine, Jennifer Paul, Maggie Neola, and Neal D. Barnard. “Ketogenic Diets and Chronic Disease: Weighing the Benefits Against the Risks.” Frontiers in Nutrition 8 (July 16, 2021): 702802. https://doi.org/10.3389/fnut.2021.702802.

Csekes, Erika, and L. Račková. “Skin Aging, Cellular Senescence and Natural Polyphenols.” International Journal of Molecular Sciences 22 (2021). https://doi.org/10.3390/ijms222312641.

Danby, F. William. “Nutrition and Aging Skin: Sugar and Glycation.” Clinics in Dermatology, Nutrition and the Skin: Part I, 28, no. 4 (July 1, 2010): 409–11. https://doi.org/10.1016/j.clindermatol.2010.03.018.

De Spirt, Silke, Wilhelm Stahl, Hagen Tronnier, Helmut Sies, Marie Bejot, Jean-Marc Maurette, and Ulrike Heinrich. “Intervention with Flaxseed and Borage Oil Supplements Modulates Skin Condition in Women.” The British Journal of Nutrition 101, no. 3 (February 2009): 440–45. https://doi.org/10.1017/S0007114508020321.

Dhaliwal, Simran, Mimi Nguyen, Alexandra R. Vaughn, Manisha Notay, Cindy J. Chambers, and Raja K. Sivamani. “Effects of Zinc Supplementation on Inflammatory Skin Diseases: A Systematic Review of the Clinical Evidence.” American Journal of Clinical Dermatology 21, no. 1 (February 1, 2020): 21–39. https://doi.org/10.1007/s40257-019-00484-0.

DiNicolantonio, James J., and James O’Keefe. “The Importance of Maintaining a Low Omega-6/Omega-3 Ratio for Reducing the Risk of Autoimmune Diseases, Asthma, and Allergies.” Missouri Medicine 118, no. 5 (2021): 453–59.

DiSilvestro, R., Joshua T. Selsby, and K. Siefker. “A Pilot Study of Copper Supplementation Effects on Plasma F2alpha Isoprostanes and Urinary Collagen Crosslinks in Young Adult Women.” Journal of Trace Elements in Medicine and Biology : Organ of the Society for Minerals and Trace Elements 24 3 (2010): 165–68. https://doi.org/10.1016/j.jtemb.2010.02.003.

Duda-Chodak, Aleksandra, and Tomasz Tarko. “Possible Side Effects of Polyphenols and Their Interactions with Medicines.” Molecules 28, no. 6 (March 10, 2023): 2536. https://doi.org/10.3390/molecules28062536.

Dumoulin, Marion, David Gaudout, and Benoit Lemaire. “Clinical Effects of an Oral Supplement Rich in Antioxidants on Skin Radiance in Women.” Clinical, Cosmetic and Investigational Dermatology 9 (October 18, 2016): 315–24. https://doi.org/10.2147/CCID.S118920.

Dwevedi, Deepti, and Ankur Srivastava. “Molecular Mechanisms of Polyphenols in Management of Skin Aging.” Current Aging Science 17 3 (2024): 180–88. https://doi.org/10.2174/0118746098287130240212085507.

Farris, Patricia K., Diane Berson, Neal Bhatia, David Goldberg, E. Lain, Kavita Mariwalla, Joshua Zeichner, Dara Miller, Tony McGuire, and Menas G. Kizoulis. “Efficacy and Tolerability of Topical 0.1% Stabilized Bioactive Retinol for Photoaging: A Vehicle-Controlled Integrated Analysis.” Journal of Drugs in Dermatology : JDD 23 4 (2024): 209–15. https://doi.org/10.36849/JDD.8124.

Flament, Frederic, Roland Bazin, Sabine Laquieze, Virginie Rubert, Elisa Simonpietri, and Bertrand Piot. “Effect of the Sun on Visible Clinical Signs of Aging in Caucasian Skin.” Clinical, Cosmetic and Investigational Dermatology 6 (September 27, 2013): 221–32. https://doi.org/10.2147/CCID.S44686.

Gao, Yan, Kit Ieng Kuok, Ying Jin, and Ruibing Wang. “Biomedical Applications of Aloe Vera.” Critical Reviews in Food Science and Nutrition 59 (2018): 244–56. https://doi.org/10.1080/10408398.2018.1496320.

Geesin, Jeffrey C., Douglas. Darr, Russel. Kaufman, Saood. Murad, and Sheldon R. Pinnell. “Ascorbic Acid Specifically Increases Type I and Type III Procollagen Messenger RNA Levels in Human Skin Fibroblasts.” Journal of Investigative Dermatology 90, no. 4 (April 1988): 420–24. https://doi.org/10.1111/1523-1747.ep12460849.

Gerster, H. “Can Adults Adequately Convert Alpha-Linolenic Acid (18:3n-3) to Eicosapentaenoic Acid (20:5n-3) and Docosahexaenoic Acid (22:6n-3)?” International Journal for Vitamin and Nutrition Research. Internationale Zeitschrift Fur Vitamin- Und Ernahrungsforschung. Journal International De Vitaminologie Et De Nutrition 68, no. 3 (1998): 159–73.

Ghazali, Nur Izyani, Rahimah Zahidah Mohd Rais, S. Makpol, K. Chin, W. Yap, and J. Goon. “Effects of Tocotrienol on Aging Skin: A Systematic Review.” Frontiers in Pharmacology 13 (2022). https://doi.org/10.3389/fphar.2022.1006198.

“Green Tea Information | Mount Sinai – New York.” Accessed February 3, 2025. https://www.mountsinai.org/health-library/herb/green-tea.

Guertler, Anne, Katharina Neu, Diana Lill, Benjamin Clanner-Engelshofen, Lars E. French, and Markus Reinholz. “Exploring the Potential of Omega-3 Fatty Acids in Acne Patients: A Prospective Intervention Study.” Journal of Cosmetic Dermatology 23, no. 10 (2024): 3295–3304. https://doi.org/10.1111/jocd.16434.

Guilbaud, Axel, Celine Niquet-Leridon, Eric Boulanger, and Frederic J. Tessier. “How Can Diet Affect the Accumulation of Advanced Glycation End-Products in the Human Body?” Foods 5, no. 4 (December 6, 2016): 84. https://doi.org/10.3390/foods5040084.

Guo, Xiaoqing, and Nan Mei. “Aloe Vera: A Review of Toxicity and Adverse Clinical Effects.” Journal of Environmental Science and Health. Part C, Environmental Carcinogenesis & Ecotoxicology Reviews 34, no. 2 (April 2, 2016): 77–96. https://doi.org/10.1080/10590501.2016.1166826.

Gupta, Mrinal, Vikram K. Mahajan, Karaninder S. Mehta, and Pushpinder S. Chauhan. “Zinc Therapy in Dermatology: A Review.” Dermatology Research and Practice 2014 (2014): 709152. https://doi.org/10.1155/2014/709152.

Haftek, Marek, Rawad Abdayem, and Pascale Guyonnet-Debersac. “Skin Minerals: Key Roles of Inorganic Elements in Skin Physiological Functions.” International Journal of Molecular Sciences 23, no. 11 (January 2022): 6267. https://doi.org/10.3390/ijms23116267.

Handeland, Katina, Mike Wakeman, and Lena Burri. “Krill Oil Supplementation Improves Transepidermal Water Loss, Hydration and Elasticity of the Skin in Healthy Adults: Results from Two Randomized, Double-Blind, Placebo-Controlled, Dose-Finding Pilot Studies.” Journal of Cosmetic Dermatology, 2024. https://doi.org/10.1111/jocd.16513.

Harris, Tamia A., Sureka Gattu, Daniel C. Propheter, Zheng Kuang, Shai Bel, Kelly A. Ruhn, Andrew L. Chara, et al. “Resistin-like Molecule α Provides Vitamin-A-Dependent Antimicrobial Protection in the Skin.” Cell Host & Microbe 25, no. 6 (June 12, 2019): 777-788.e8. https://doi.org/10.1016/j.chom.2019.04.004.

Hasrat, Nazik H, and Asaad Q Al-Yassen. “The Relationship Between Acne Vulgaris and Insulin Resistance.” Cureus 15, no. 1 (n.d.): e34241. https://doi.org/10.7759/cureus.34241.

Heinrich, U., C. Moore, S. De Spirt, H. Tronnier, and W. Stahl. “Green Tea Polyphenols Provide Photoprotection, Increase Microcirculation, and Modulate Skin Properties of Women.” The Journal of Nutrition 141 6 (2011): 1202–8. https://doi.org/10.3945/jn.110.136465.

Hekmatpou, Davood, Fatemeh Mehrabi, Kobra Rahzani, and Atefeh Aminiyan. “The Effect of Aloe Vera Clinical Trials on Prevention and Healing of Skin Wound: A Systematic Review.” Iranian Journal of Medical Sciences 44, no. 1 (January 2019): 1–9.

Jeong, Jae-Hong, Mi-Bo Kim, Changhee Kim, and J. Hwang. “Inhibitory Effect of Vitamin C on Intrinsic Aging in Human Dermal Fibroblasts and Hairless Mice.” Food Science and Biotechnology 27 (2017): 555–64. https://doi.org/10.1007/s10068-017-0252-6.

Jung, Jae Yoon, Hyuck Hoon Kwon, Jong Soo Hong, Ji Young Yoon, Mi Sun Park, Mi Young Jang, and Dae Hun Suh. “Effect of Dietary Supplementation with Omega-3 Fatty Acid and Gamma-Linolenic Acid on Acne Vulgaris: A Randomised, Double-Blind, Controlled Trial.” Acta Dermato-Venereologica 94, no. 5 (January 29, 2014): 521–25. https://doi.org/10.2340/00015555-1802.

Kaminaka, C., Yuki Yamamoto, Mariko Sakata, C. Hamamoto, Eriko Misawa, K. Nabeshima, Marie Saito, Miyuki Tanaka, F. Abe, and M. Jinnin. “Effects of Low‐dose Aloe Sterol Supplementation on Skin Moisture, Collagen Score and Objective or Subjective Symptoms: 12‐week, Double‐blind, Randomized Controlled Trial.” The Journal of Dermatology 47 (2020): 998–1006. https://doi.org/10.1111/1346-8138.15428.

Khalid, Aminah, Zahid Iqbal, Sami-Ur- Rehman, and Zainab Yousaf. “Role of Vitamin C in Skin Aging Mechanism-A Narrative Review.” Journal of Health and Rehabilitation Research, 2024. https://doi.org/10.61919/jhrr.v4i2.1078.

Kim, Min Ah, Eun Joo Kim, Byung Young Kang, and Hae Kwang Lee. “The Effects of Sleep Deprivation on the Biophysical Properties of Facial Skin.” Journal of Cosmetics, Dermatological Sciences and Applications 7, no. 1 (January 19, 2017): 34–47. https://doi.org/10.4236/jcdsa.2017.71004.

Kivirikko, Kari I., and Darwin J. Prockop. “ENZYMATIC HYDROXYLATION OF PROLINE AND LYSINE IN PROTOCOLLAGEN*.” Proceedings of the National Academy of Sciences of the United States of America 57, no. 3 (March 1967): 782–89.

Kwack, S., Kyu Bong Kim, and B. Lee. “Estimation of Tolerable Upper Intake Level (UL) of Active Aloe.” Journal of Toxicology and Environmental Health, Part A 72 (2009): 1455–62. https://doi.org/10.1080/15287390903212931.

Latreille, Julie, Emmanuelle Kesse-Guyot, Denis Malvy, Valentina Andreeva, Pilar Galan, Erwin Tschachler, Serge Hercberg, Christiane Guinot, and Khaled Ezzedine. “Association between Dietary Intake of N-3 Polyunsaturated Fatty Acids and Severity of Skin Photoaging in a Middle-Aged Caucasian Population.” Journal of Dermatological Science 72, no. 3 (December 2013): 233–39. https://doi.org/10.1016/j.jdermsci.2013.07.006.

Lauer, A., N. Groth, S. Haag, M. Darvin, J. Lademann, and M. Meinke. “Dose-Dependent Vitamin C Uptake and Radical Scavenging Activity in Human Skin Measured with in Vivo Electron Paramagnetic Resonance Spectroscopy.” Skin Pharmacology and Physiology 26 (2013): 147–54. https://doi.org/10.1159/000350833.

Lee, M. J., Gaurav Agrahari, H. Kim, Eun-Joo An, Kyung-Hee Chun, Hyeokgu Kang, Yeon-Soo Kim, C. Bang, Lee-Jung Tak, and Tae-Yoon Kim. “Extracellular Superoxide Dismutase Prevents Skin Aging by Promoting Collagen Production via Activation of AMPK and Nrf2/HO-1 Cascades.” The Journal of Investigative Dermatology, 2021. https://doi.org/10.1016/j.jid.2021.02.757.

Lee, Miyeong, Eunjoung Kim, H. Ahn, S. Son, and Hyunjun Lee. “Oral Intake of Collagen Peptide NS Improves Hydration, Elasticity, Desquamation, and Wrinkling in Human Skin: A Randomized, Double-Blinded, Placebo-Controlled Study.” Food & Function, 2023. https://doi.org/10.1039/d2fo02958h.

Lee, Seung Jin, M. Ko, Yung-Hun Yang, and Sang-mo Kang. “Long- and Short-Term Effects of Vitamin E Administration along with Stress on Skin Tissues of Mice.” Journal of the Korean Society for Applied Biological Chemistry 55 (2012): 105–9. https://doi.org/10.1007/s13765-012-0018-z.

Linus Pauling Institute. “Supplemental Forms,” October 21, 2014. https://lpi.oregonstate.edu/mic/vitamins/vitamin-C/supplemental-forms.

Linus Pauling Institute. “Vitamin A,” April 22, 2014. https://lpi.oregonstate.edu/mic/vitamins/vitamin-A.

Lipkin, G., C. March, and J. Gowdey. “MAGNESIUM IN EPIDERMIS, DERMIS, AND WHOLE SKIN OF NORMAL AND ATOPIC SUBJECTS.” The Journal of Investigative Dermatology 42 (1964): 293–304. https://doi.org/10.1038/JID.1964.69.

Luca, S., I. Macovei, Alexandra Bujor, A. Miron, K. Skalicka‐Woźniak, A. C. Aprotosoaie, and A. Trifan. “Bioactivity of Dietary Polyphenols: The Role of Metabolites.” Critical Reviews in Food Science and Nutrition 60 (2020): 626–59. https://doi.org/10.1080/10408398.2018.1546669.

Ma, Guiling, and Yanting Chen. “Polyphenol Supplementation Benefits Human Health via Gut Microbiota: A Systematic Review via Meta-Analysis.” Journal of Functional Foods 66 (2020). https://doi.org/10.1016/j.jff.2020.103829.

Martin, Keith R. “Polyphenols as Dietary Supplements: A Double-Edged Sword.” Nutrition and Dietary Supplements, December 2009, 1. https://doi.org/10.2147/NDS.S6422.

Martínez-González, Miguel A., Jordi Salas-Salvadó, Ramón Estruch, Dolores Corella, Montse Fitó, and Emilio Ros. “Benefits of the Mediterranean Diet: Insights From the PREDIMED Study.” Progress in Cardiovascular Diseases, Preventive Cardiology Update: Controversy, Concensus, and Future Promise, 58, no. 1 (July 1, 2015): 50–60. https://doi.org/10.1016/j.pcad.2015.04.003.

Mayo Clinic. “Aloe.” Accessed January 9, 2025. https://www.mayoclinic.org/drugs-supplements-aloe/art-20362267.

Mayo Clinic. “Low-Glycemic Index Diet: What’s behind the Claims?” Accessed March 18, 2025. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/low-glycemic-index-diet/art-20048478.

Mayo Clinic. “Vitamin A.” Accessed December 13, 2024. https://www.mayoclinic.org/drugs-supplements-vitamin-a/art-20365945.

Mc, Branchet, S. Boisnic, C. Francès, C. Lesty, and Ladislas Robert. “Morphometric Analysis of Dermal Collagen Fibers in Normal Human Skin as a Function of Age.” Archives of Gerontology and Geriatrics 13 1 (1991): 1–14. https://doi.org/10.1016/0167-4943(91)90011-E.

McArdle, F., L. Rhodes, R. Parslew, G. Close, C. Jack, P. Friedmann, and M. Jackson. “Effects of Oral Vitamin E and Beta-Carotene Supplementation on Ultraviolet Radiation-Induced Oxidative Stress in Human Skin.” The American Journal of Clinical Nutrition 80 5 (2004): 1270–75. https://doi.org/10.1093/AJCN/80.5.1270.

McArdle, Francis, Lesley E. Rhodes, R. Parslew, Cia Jack, Peter S. Friedmann, and Malcolm J. Jackson. “UVR-Induced Oxidative Stress in Human Skin in Vivo: Effects of Oral Vitamin C Supplementation.” Free Radical Biology & Medicine 33 10 (2002): 1355–62. https://doi.org/10.1016/S0891-5849(02)01042-0.

Mennen, Louise I., Ron Walker, Catherine Bennetau-Pelissero, and Augustin Scalbert. “Risks and Safety of Polyphenol Consumption.” The American Journal of Clinical Nutrition 81, no. 1 Suppl (January 2005): 326S-329S. https://doi.org/10.1093/ajcn/81.1.326S.

Menter, J., A. Patta, Thomas D. Hollins, C. Moore, and I. Willis. “Photoprotection of Mammalian Acid‐Soluble Collagen by Cuttlefish Sepia Melanin In Vitro.” Photochemistry and Photobiology 68 (1998). https://doi.org/10.1111/j.1751-1097.1998.tb02510.x.

Michalak, Monika, Monika Pierzak, Beata Kręcisz, and Edyta Suliga. “Bioactive Compounds for Skin Health: A Review.” Nutrients 13, no. 1 (January 12, 2021): 203. https://doi.org/10.3390/nu13010203.

Milani, Massimo, and Francesca Colombo. “Skin Anti-Aging Effect of Oral Vitamin A Supplementation in Combination with Topical Retinoic Acid Treatment in Comparison with Topical Treatment Alone: A Randomized, Prospective, Assessor-Blinded, Parallel Trial.” Cosmetics 10, no. 5 (October 2023): 144. https://doi.org/10.3390/cosmetics10050144.

Miura, Kyoko, Andy Vail, Daniel Chambers, Peter M. Hopkins, Lisa Ferguson, Michelle Grant, Lesley E. Rhodes, and Adèle C. Green. “Omega-3 Fatty Acid Supplement Skin Cancer Prophylaxis in Lung Transplant Recipients: A Randomized, Controlled Pilot Trial.” The Journal of Heart and Lung Transplantation 38, no. 1 (January 1, 2019): 59–65. https://doi.org/10.1016/j.healun.2018.09.009.

Moon, T. E., N. Levine, B. Cartmel, J. L. Bangert, S. Rodney, Q. Dong, Y. M. Peng, and D. S. Alberts. “Effect of Retinol in Preventing Squamous Cell Skin Cancer in Moderate-Risk Subjects: A Randomized, Double-Blind, Controlled Trial. Southwest Skin Cancer Prevention Study Group.” Cancer Epidemiology, Biomarkers & Prevention: A Publication of the American Association for Cancer Research, Cosponsored by the American Society of Preventive Oncology 6, no. 11 (November 1997): 949–56.

Mount Sinai Health System. “Aloe Information | Mount Sinai – New York.” Accessed February 19, 2025. https://www.mountsinai.org/health-library/herb/aloe.

Nachbar, F., and H. Korting. “The Role of Vitamin E in Normal and Damaged Skin.” Journal of Molecular Medicine 73 (2004): 7–17. https://doi.org/10.1007/BF00203614.

Nash, Victoria A., C. Ranadheera, E. Georgousopoulou, D. Mellor, D. Panagiotakos, A. Mckune, J. Kellett, and N. Naumovski. “The Effects of Grape and Red Wine Polyphenols on Gut Microbiota – A Systematic Review.” Food Research International 113 (2018): 277–87. https://doi.org/10.1016/j.foodres.2018.07.019.

Navarro, S., R. Valderrama, J. To-Figueras, A. Giménez, J. López, E. Campo, L. Fernández‐Cruz, E. Ros, J. Caballería, and A. Parés. “Role of Zinc in the Process of Pancreatic Fibrosis in Chronic Alcoholic Pancreatitis.” Pancreas 9 (1994). https://doi.org/10.1097/00006676-199403000-00020.

Nichols, J. A., and S. Katiyar. “Skin Photoprotection by Natural Polyphenols: Anti-Inflammatory, Antioxidant and DNA Repair Mechanisms.” Archives of Dermatological Research 302 (2010): 71–83. https://doi.org/10.1007/s00403-009-1001-3.

Noronha, Luana Alberti, Camila Tureck, Vânia Zanella Pinto, and Eloá Angélica Koehnlein. “Dietary Polyphenols: What Is the Estimated Intake in Population Studies With Adults and Elderly People?” Current Nutrition Reports 13, no. 2 (June 1, 2024): 280–93. https://doi.org/10.1007/s13668-024-00530-2.

Nunes, A., C. A. Minetti, D. P. Remeta, and J. Baum. “Magnesium Activates Microsecond Dynamics to Regulate Integrin-Collagen Recognition.” Structure 26 8 (2018): 1080–10905. https://doi.org/10.1016/j.str.2018.05.010.

Nusgens, B., Philippe Humbert, André Rougier, A. Colige, Marek Haftek, C. Lambert, Alain Richard, P. Creidi, and C. Lapière. “Topically Applied Vitamin C Enhances the mRNA Level of Collagens I and III, Their Processing Enzymes and Tissue Inhibitor of Matrix Metalloproteinase 1 in the Human Dermis.” The Journal of Investigative Dermatology 116 6 (2001): 853–59. https://doi.org/10.1046/J.0022-202X.2001.01362.X.

“Office of Dietary Supplements – Copper.” Accessed January 3, 2025. https://ods.od.nih.gov/factsheets/Copper-HealthProfessional/.

“Office of Dietary Supplements – Magnesium.” Accessed January 3, 2025. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/.

“Office of Dietary Supplements – Omega-3 Fatty Acids.” Accessed December 16, 2024. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/.

“Office of Dietary Supplements – Vitamin A and Carotenoids.” Accessed December 15, 2024. https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/.

“Office of Dietary Supplements – Vitamin C.” Accessed November 26, 2024. https://ods.od.nih.gov/factsheets/VitaminC-Consumer/.

“Office of Dietary Supplements – Vitamin C.” Accessed December 8, 2024. https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/.

“Office of Dietary Supplements – Vitamin E.” Accessed December 15, 2024. https://ods.od.nih.gov/factsheets/VitaminE-HealthProfessional/.

“Office of Dietary Supplements – Zinc.” Accessed January 3, 2025. https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/.

Pfeffer, F., E. Casanueva, J. Kamar, A. Guerra, O. Perichart, and F. Vadillo-Ortega. “Modulation of 72-Kilodalton Type IV Collagenase (Matrix Metalloproteinase-2) by Ascorbic Acid in Cultured Human Amnion-Derived Cells.” Biology of Reproduction 59 2 (1998): 326–29. https://doi.org/10.1095/BIOLREPROD59.2.326.

Pilkington, Suzanne M., Rachel E. B Watson, Anna Nicolaou, and Lesley E. Rhodes. “Omega-3 Polyunsaturated Fatty Acids: Photoprotective Macronutrients.” Experimental Dermatology 20, no. 7 (2011): 537–43. https://doi.org/10.1111/j.1600-0625.2011.01294.x.

Pincemail, J., and S. Meziane. “On the Potential Role of the Antioxidant Couple Vitamin E/Selenium Taken by the Oral Route in Skin and Hair Health.” Antioxidants 11 (2022). https://doi.org/10.3390/antiox11112270.

Podgórska, Aleksandra, Aleksandra Kicman, Sylwia Naliwajko, Marta Wacewicz-Muczyńska, and Marek Niczyporuk. “Zinc, Copper, and Iron in Selected Skin Diseases.” International Journal of Molecular Sciences 25, no. 7 (January 2024): 3823. https://doi.org/10.3390/ijms25073823.

Posey, Karen L. “Curcumin and Resveratrol: Nutraceuticals with so Much Potential for Pseudoachondroplasia and Other ER-Stress Conditions.” Biomolecules 14, no. 2 (January 27, 2024): 154. https://doi.org/10.3390/biom14020154.

Proksch, Ehrhardt, Hans-Peter Nissen, Markus Bremgartner, and Colin Urquhart. “Bathing in a Magnesium-Rich Dead Sea Salt Solution Improves Skin Barrier Function, Enhances Skin Hydration, and Reduces Inflammation in Atopic Dry Skin.” International Journal of Dermatology 44, no. 2 (2005): 151–57. https://doi.org/10.1111/j.1365-4632.2005.02079.x.

Pullar, Juliet M., Anitra C. Carr, and Margreet C. M. Vissers. “The Roles of Vitamin C in Skin Health.” Nutrients 9, no. 8 (August 12, 2017): 866. https://doi.org/10.3390/nu9080866.

Purba, M. B., A. Kouris-Blazos, N. Wattanapenpaiboon, W. Lukito, E. M. Rothenberg, B. C. Steen, and M. L. Wahlqvist. “Skin Wrinkling: Can Food Make a Difference?” Journal of the American College of Nutrition 20, no. 1 (February 2001): 71–80. https://doi.org/10.1080/07315724.2001.10719017.

Queipo-Ortuño, M. I., M. Boto-Ordoñez, M. Murri, J. M. Gómez-Zumaquero, M. Clemente-Postigo, R. Estruch, Fernando Cardona Diaz, C. Andrés-Lacueva, and F. Tinahones. “Influence of Red Wine Polyphenols and Ethanol on the Gut Microbiota Ecology and Biochemical Biomarkers.” The American Journal of Clinical Nutrition 95 6 (2012): 1323–34. https://doi.org/10.3945/ajcn.111.027847.

Rahmanian, Elham, Nader Tanideh, Saied Karbalay-doust, Davood Mehrabani, Davood Rezazadeh, Deniz Ketabchi, Narges EskandariRoozbahani, Nasrin Hamidizadeh, Farzad Rahmanian, and Mohammad Reza Namazi. “The Effect of Topical Magnesium on Healing of Pre-Clinical Burn Wounds.” Burns 50, no. 3 (April 1, 2024): 630–40. https://doi.org/10.1016/j.burns.2023.10.015.

———. “The Effect of Topical Magnesium on Healing of Pre-Clinical Burn Wounds.” Burns 50, no. 3 (April 1, 2024): 630–40. https://doi.org/10.1016/j.burns.2023.10.015.

Raise-Abdullahi, Payman, Mehrnaz Rezvani, Fatemeh Yousefi, Sadaf Rahmani, Morvarid Meamar, Ehsan Raeis-Abdollahi, Abbas Ali Vafaei, Hamed Rashidipour, and Ali Rashidy-Pour. “Natural Polyphenols as Therapeutic Candidates for Mitigating Neuropsychiatric Symptoms in Post-Traumatic Stress Disorder: Evidence from Preclinical Studies.” Progress in Neuro-Psychopharmacology and Biological Psychiatry 136 (January 10, 2025): 111230. https://doi.org/10.1016/j.pnpbp.2024.111230.

Ratz-Łyko, Anna, J. Arct, S. Majewski, and K. Pytkowska. “Influence of Polyphenols on the Physiological Processes in the Skin.” Phytotherapy Research 29 (2015): 509–17. https://doi.org/10.1002/ptr.5289.

Rhodes, Lesley E., Hassan Shahbakhti, Richard M. Azurdia, Ralf M.W. Moison, Marie-Jose S.T. Steenwinkel, Marie I. Homburg, Michael P. Dean, et al. “Effect of Eicosapentaenoic Acid, an Omega-3 Polyunsaturated Fatty Acid, on UVR-Related Cancer Risk in Humans. An Assessment of Early Genotoxic Markers.” Carcinogenesis 24, no. 5 (May 1, 2003): 919–25. https://doi.org/10.1093/carcin/bgg038.

Roberts, Wendy. “Air Pollution and Skin Disorders.” International Journal of Women’s Dermatology, Special Issue on Climate Change & Dermatology, 7, no. 1 (January 1, 2021): 91–97. https://doi.org/10.1016/j.ijwd.2020.11.001.

Roche, Fritzlaine C., and T. Harris-Tryon. “Illuminating the Role of Vitamin A in Skin Innate Immunity and the Skin Microbiome: A Narrative Review.” Nutrients 13 (2021). https://doi.org/10.3390/nu13020302.

Rosenbloom, Joel, Margaret Harsch, and Sergio Jimenez. “Hydroxyproline Content Determines the Denaturation Temperature of Chick Tendon Collagen.” Archives of Biochemistry and Biophysics 158, no. 2 (October 1, 1973): 478–84. https://doi.org/10.1016/0003-9861(73)90539-0.

Rostan, Elizabeth F., Holly V. DeBuys, Doren L. Madey, and Sheldon R. Pinnell. “Evidence Supporting Zinc as an Important Antioxidant for Skin.” International Journal of Dermatology 41, no. 9 (September 2002): 606–11. https://doi.org/10.1046/j.1365-4362.2002.01567.x.

Rucker, R., T. Kosonen, M. Clegg, A. Mitchell, B. Rucker, J. Y. Uriu-Hare, and C. Keen. “Copper, Lysyl Oxidase, and Extracellular Matrix Protein Cross-Linking.” The American Journal of Clinical Nutrition 67 5 Suppl (1998): 996–1002. https://doi.org/10.1093/ajcn/67.5.996S.

Saito, Marie, Miyuki Tanaka, Eriko Misawa, Ruiquing Yao, Kazumi Nabeshima, Kouji Yamauchi, Fumiaki Abe, Yuki Yamamoto, and Fukumi Furukawa. “Oral Administration of Aloe Vera Gel Powder Prevents UVB-Induced Decrease in Skin Elasticity via Suppression of Overexpression of MMPs in Hairless Mice.” Bioscience, Biotechnology, and Biochemistry 80, no. 7 (July 2, 2016): 1416–24. https://doi.org/10.1080/09168451.2016.1156480.

Sankova, Maria V., Vladimir N. Nikolenko, Marine V. Oganesyan, Sergey V. Sankov, Mikhail Y. Sinelnikov, Andrey V. Suslov, Aleksandra S. Trishina, Tatyana S. Zharikova, André Pontes-Silva, and Yury O. Zharikov. “Magnesium Deficiency and Its Interaction with the Musculoskeletal System, Exercise, and Connective Tissue: An Evidence Synthesis.” Sport Sciences for Health 20, no. 3 (September 1, 2024): 715–26. https://doi.org/10.1007/s11332-024-01179-8.

Shahidi, Fereidoon, and Priyatharini Ambigaipalan. “Omega-3 Polyunsaturated Fatty Acids and Their Health Benefits.” Annual Review of Food Science and Technology 9, no. 1 (March 25, 2018): 345–81. https://doi.org/10.1146/annurev-food-111317-095850.

Shaw, Gregory, Ann Lee-Barthel, Megan Lr Ross, Bing Wang, and Keith Baar. “Vitamin C–Enriched Gelatin Supplementation before Intermittent Activity Augments Collagen Synthesis.” The American Journal of Clinical Nutrition 105, no. 1 (January 2017): 136–43. https://doi.org/10.3945/ajcn.116.138594.

Shoji, T., Saeko Masumoto, Nina Moriichi, Y. Ohtake, and T. Kanda. “Administration of Apple Polyphenol Supplements for Skin Conditions in Healthy Women: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial.” Nutrients 12 (2020). https://doi.org/10.3390/nu12041071.

“Skin Care Products Market Size And Share Report, 2030.” Accessed December 10, 2024. https://www.grandviewresearch.com/industry-analysis/skin-care-products-market.

“Smoking and Its Effects on Skin – American Osteopathic College of Dermatology (AOCD).” Accessed December 18, 2024. https://www.aocd.org/page/Smoking.

Sun, Mang, Ya Deng, Xining Cao, Lu Xiao, Qian Ding, Fuqing Luo, Peng Huang, Yuanyuan Gao, Mengqi Liu, and Hengguang Zhao. “Effects of Natural Polyphenols on Skin and Hair Health: A Review.” Molecules 27, no. 22 (November 14, 2022): 7832. https://doi.org/10.3390/molecules27227832.

Sun, Mang-Lang, Yanye Deng, Xi-ning Cao, Lu Xiao, Qian Ding, Fuqing Luo, Peng Huang, Yuanyuan Gao, Mengqi Liu, and Hengguang Zhao. “Effects of Natural Polyphenols on Skin and Hair Health: A Review.” Molecules 27 (2022). https://doi.org/10.3390/molecules27227832.

Sun, Qian, Jingping Wu, Guofei Qian, and Hongbin Cheng. “Effectiveness of Dietary Supplement for Skin Moisturizing in Healthy Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.” Frontiers in Nutrition 9 (June 2, 2022). https://doi.org/10.3389/fnut.2022.895192.

Surjushe, Amar, Resham Vasani, and D G Saple. “ALOE VERA: A SHORT REVIEW.” Indian Journal of Dermatology 53, no. 4 (2008): 163–66. https://doi.org/10.4103/0019-5154.44785.

Swanson, Danielle, R. Block, and S. Mousa. “Omega-3 Fatty Acids EPA and DHA: Health Benefits throughout Life.” Advances in Nutrition 3 1 (2012): 1–7. https://doi.org/10.3945/an.111.000893.

Tanaka, Miyuki, Yuki Yamamoto, Eriko Misawa, K. Nabeshima, Marie Saito, K. Yamauchi, F. Abe, and F. Furukawa. “Effects of Aloe Sterol Supplementation on Skin Elasticity, Hydration, and Collagen Score: A 12-Week Double-Blind, Randomized, Controlled Trial.” Skin Pharmacology and Physiology 29 (2017): 309–17. https://doi.org/10.1159/000454718.

———. “Effects of Aloe Sterol Supplementation on Skin Elasticity, Hydration, and Collagen Score: A 12-Week Double-Blind, Randomized, Controlled Trial.” Skin Pharmacology and Physiology 29 (2017): 309–17. https://doi.org/10.1159/000454718.

Tapiero, H, K. D Tew, G Nguyen Ba, and G Mathé. “Polyphenols: Do They Play a Role in the Prevention of Human Pathologies?” Biomedicine & Pharmacotherapy 56, no. 4 (June 1, 2002): 200–207. https://doi.org/10.1016/S0753-3322(02)00178-6.

Tfayli, A., D. Jamal, R. Vyumvuhore, M. Manfait, and A. Baillet-Guffroy. “Hydration Effects on the Barrier Function of Stratum Corneum Lipids: Raman Analysis of Ceramides 2, III and 5.” The Analyst 138 21 (2013): 6582–88. https://doi.org/10.1039/c3an00604b.

The Nutrition Source. “Collagen,” May 26, 2021. https://nutritionsource.hsph.harvard.edu/collagen/.

The Skin Cancer Foundation. “UV Radiation.” Accessed December 18, 2024. https://www.skincancer.org/risk-factors/uv-radiation/.

Thiele, J., and S. Ekanayake-Mudiyanselage. “Vitamin E in Human Skin: Organ-Specific Physiology and Considerations for Its Use in Dermatology.” Molecular Aspects of Medicine 28 5-6 (2007): 646–67. https://doi.org/10.1016/J.MAM.2007.06.001.

Thiele, J., S. N. Hsieh, and S. Ekanayake-Mudiyanselage. “Vitamin E: Critical Review of Its Current Use in Cosmetic and Clinical Dermatology.” Dermatologic Surgery : Official Publication for American Society for Dermatologic Surgery [et Al.] 31 7 Pt 2 (2006): 805–13813. https://doi.org/10.1111/J.1524-4725.2005.31724.

Thomsen, Bryce J., Eunice Y. Chow, and M. Sapijaszko. “The Potential Uses of Omega-3 Fatty Acids in Dermatology: A Review.” Journal of Cutaneous Medicine and Surgery 24 (2020): 481–94. https://doi.org/10.1177/1203475420929925.

“Tolerable Upper Intake Level of EPA, DHA and DPA | EFSA,” July 27, 2012. https://www.efsa.europa.eu/en/efsajournal/pub/2815.

“Undetectable Intracellular Free Copper: The Requirement of a Copper Chaperone for Superoxide Dismutase. – Consensus.” Accessed January 3, 2025. https://consensus.app/papers/undetectable-intracellular-free-copper-the-requirement-rae-schmidt/2246fe7854895ce59d5e3cad71ebce6e/.

VanBuren, Christine A., and H. Everts. “Vitamin A in Skin and Hair: An Update.” Nutrients 14 (2022). https://doi.org/10.3390/nu14142952.

Varani, J., R. Warner, M. Gharaee-Kermani, S. Phan, Sewon Kang, J. Chung, Zengquan Wang, Subhash C. Datta, G. Fisher, and J. Voorhees. “Vitamin A Antagonizes Decreased Cell Growth and Elevated Collagen-Degrading Matrix Metalloproteinases and Stimulates Collagen Accumulation in Naturally Aged Human Skin.” The Journal of Investigative Dermatology 114 3 (2000): 480–86. https://doi.org/10.1046/J.1523-1747.2000.00902.X.

Varghese, Jeffrey Alex, Victor L. Quan, Maria L. Colavincenzo, and Lida Zheng. “Acquired Perforating Dermatosis in Patients with Copper Deficiency.” JAAD Case Reports 15 (July 27, 2021): 110–14. https://doi.org/10.1016/j.jdcr.2021.07.017.

Vaughn, A. R., N. Foolad, M. Maarouf, K. Tran, and V. Shi. “Micronutrients in Atopic Dermatitis: A Systematic Review.” Journal of Alternative and Complementary Medicine 25 6 (2019): 567–77. https://doi.org/10.1089/acm.2018.0363.

“Vitamin C – Health Professional Fact Sheet.” Accessed January 14, 2025. https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/.

Whitehead, Ross D., Daniel Re, Dengke Xiao, Gozde Ozakinci, and David I. Perrett. “You Are What You Eat: Within-Subject Increases in Fruit and Vegetable Consumption Confer Beneficial Skin-Color Changes.” PLoS ONE 7, no. 3 (March 7, 2012): e32988. https://doi.org/10.1371/journal.pone.0032988.

Yagi, A., A. Kabash, N. Okamura, H. Haraguchi, S. M. Moustafa, and T. I. Khalifa. “Antioxidant, Free Radical Scavenging and Anti-Inflammatory Effects of Aloesin Derivatives in Aloe Vera.” Planta Medica 68 (November 26, 2002): 957–60. https://doi.org/10.1055/s-2002-35666.

Yu, Xiaoping, Haomou Pu, and Margaret Voss. “Overview of Anti-Inflammatory Diets and Their Promising Effects on Non-Communicable Diseases.” The British Journal of Nutrition 132, no. 7 (n.d.): 898–918. https://doi.org/10.1017/S0007114524001405.

Yuan, Wenlin, S. Burleigh, and J. Dawson. “Melanin Biosynthesis by Frankia Strain CeI5.” Physiologia Plantarum 131 2 (2007): 180–90. https://doi.org/10.1111/j.1399-3054.2007.00948.x.

Zebrowitz, Leslie A., and Joann M. Montepare. “Social Psychological Face Perception: Why Appearance Matters.” Social and Personality Psychology Compass 2, no. 3 (May 1, 2008): 1497. https://doi.org/10.1111/j.1751-9004.2008.00109.x.

Zhao, Yiying, and Q. Jiang. “Roles of the Polyphenol-Gut Microbiota Interaction in Alleviating Colitis and Preventing Colitis-Associated Colorectal Cancer.” Advances in Nutrition, 2020. https://doi.org/10.1093/advances/nmaa104.

---

1. Marion Dumoulin, David Gaudout, and Benoit Lemaire, “Clinical Effects of an Oral Supplement Rich in Antioxidants on Skin Radiance in Women,” Clinical, Cosmetic and Investigational Dermatology 9 (October 18, 2016): 315–24, https://doi.org/10.2147/CCID.S118920.↩︎

2. Miyeong Lee et al., “Oral Intake of Collagen Peptide NS Improves Hydration, Elasticity, Desquamation, and Wrinkling in Human Skin: A Randomized, Double-Blinded, Placebo-Controlled Study.,” Food & Function, 2023, https://doi.org/10.1039/d2fo02958h; Silke Altgilbers et al., “A Biomimetic Combination of Actives Enhances Skin Hydration and Barrier Function via Modulation of Gene Expression: Results of Two Double-Blind, Vehicle-Controlled Clinical Studies,” Skin Pharmacology and Physiology 35 (2021): 102–11, https://doi.org/10.1159/000520009.↩︎

3. Lee et al., “Oral Intake of Collagen Peptide NS Improves Hydration, Elasticity, Desquamation, and Wrinkling in Human Skin.”↩︎

4. Min Ah Kim et al., “The Effects of Sleep Deprivation on the Biophysical Properties of Facial Skin,” Journal of Cosmetics, Dermatological Sciences and Applications 7, no. 1 (January 19, 2017): 34–47, https://doi.org/10.4236/jcdsa.2017.71004.↩︎

5. “UV Radiation,” The Skin Cancer Foundation (blog), accessed December 18, 2024, https://www.skincancer.org/risk-factors/uv-radiation/.↩︎

6. “Smoking and Its Effects on Skin – American Osteopathic College of Dermatology (AOCD),” accessed December 18, 2024, https://www.aocd.org/page/Smoking.↩︎

7. Changwei Cao et al., “Diet and Skin Aging—From the Perspective of Food Nutrition,” Nutrients 12, no. 3 (March 24, 2020): 870, https://doi.org/10.3390/nu12030870.↩︎

8. “Skin Care Products Market Size And Share Report, 2030,” accessed December 10, 2024, https://www.grandviewresearch.com/industry-analysis/skin-care-products-market.↩︎

9. “Integumentary System: What It Is, Function & Organs,” Cleveland Clinic, accessed March 18, 2025, https://my.clevelandclinic.org/health/body/22827-integumentary-system.↩︎

10. Frederic Flament et al., “Effect of the Sun on Visible Clinical Signs of Aging in Caucasian Skin,” Clinical, Cosmetic and Investigational Dermatology 6 (September 27, 2013): 221–32, https://doi.org/10.2147/CCID.S44686.↩︎

11. Wendy Roberts, “Air Pollution and Skin Disorders,” International Journal of Women’s Dermatology, Special Issue on Climate Change & Dermatology, 7, no. 1 (January 1, 2021): 91–97, https://doi.org/10.1016/j.ijwd.2020.11.001.↩︎

12. Leslie A. Zebrowitz and Joann M. Montepare, “Social Psychological Face Perception: Why Appearance Matters,” Social and Personality Psychology Compass 2, no. 3 (May 1, 2008): 1497, https://doi.org/10.1111/j.1751-9004.2008.00109.x.↩︎

13. “Acne Can Affect More than Your Skin,” accessed January 27, 2025, https://www.aad.org/public/diseases/acne/acne-emotional-effects.↩︎

14. Changwei Cao et al., “Diet and Skin Aging—From the Perspective of Food Nutrition,” Nutrients 12, no. 3 (March 24, 2020): 870, https://doi.org/10.3390/nu12030870.↩︎

15. Ross D. Whitehead et al., “You Are What You Eat: Within-Subject Increases in Fruit and Vegetable Consumption Confer Beneficial Skin-Color Changes,” PLoS ONE 7, no. 3 (March 7, 2012): e32988, https://doi.org/10.1371/journal.pone.0032988.↩︎

16. Monika Michalak et al., “Bioactive Compounds for Skin Health: A Review,” Nutrients 13, no. 1 (January 12, 2021): 203, https://doi.org/10.3390/nu13010203.↩︎

17. Patricia K. Farris et al., “Efficacy and Tolerability of Topical 0.1% Stabilized Bioactive Retinol for Photoaging: A Vehicle-Controlled Integrated Analysis.,” Journal of Drugs in Dermatology : JDD 23 4 (2024): 209–15, https://doi.org/10.36849/JDD.8124.↩︎

18. “Office of Dietary Supplements – Vitamin A and Carotenoids,” accessed December 15, 2024, https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/.↩︎

19. F. Al‐Niaimi and N. Y. Chiang, “Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications.,” The Journal of Clinical and Aesthetic Dermatology 10 7 (2017): 14–17.↩︎

20. J. Varani et al., “Vitamin A Antagonizes Decreased Cell Growth and Elevated Collagen-Degrading Matrix Metalloproteinases and Stimulates Collagen Accumulation in Naturally Aged Human Skin.,” The Journal of Investigative Dermatology 114 3 (2000): 480–86, https://doi.org/10.1046/J.1523-1747.2000.00902.X.↩︎

21. Fritzlaine C. Roche and T. Harris-Tryon, “Illuminating the Role of Vitamin A in Skin Innate Immunity and the Skin Microbiome: A Narrative Review,” Nutrients 13 (2021), https://doi.org/10.3390/nu13020302.↩︎

22. Tamia A. Harris et al., “Resistin-like Molecule α Provides Vitamin-A-Dependent Antimicrobial Protection in the Skin,” Cell Host & Microbe 25, no. 6 (June 12, 2019): 777-788.e8, https://doi.org/10.1016/j.chom.2019.04.004.↩︎

23. Christine A. VanBuren and H. Everts, “Vitamin A in Skin and Hair: An Update,” Nutrients 14 (2022), https://doi.org/10.3390/nu14142952.↩︎

24. K. Beer et al., “A Comprehensive Review on the Role of Vitamin A on Human Health and Nutrition,” Journal of Environmental Biology, 2024, https://doi.org/10.22438/jeb/45/6/mrn-5339.↩︎

25. F. McArdle et al., “Effects of Oral Vitamin E and Beta-Carotene Supplementation on Ultraviolet Radiation-Induced Oxidative Stress in Human Skin.,” The American Journal of Clinical Nutrition 80 5 (2004): 1270–75, https://doi.org/10.1093/AJCN/80.5.1270; J. Thiele, S. N. Hsieh, and S. Ekanayake-Mudiyanselage, “Vitamin E: Critical Review of Its Current Use in Cosmetic and Clinical Dermatology.,” Dermatologic Surgery : Official Publication for American Society for Dermatologic Surgery [et Al.] 31 7 Pt 2 (2006): 805–13813, https://doi.org/10.1111/J.1524-4725.2005.31724; J. Thiele and S. Ekanayake-Mudiyanselage, “Vitamin E in Human Skin: Organ-Specific Physiology and Considerations for Its Use in Dermatology.,” Molecular Aspects of Medicine 28 5-6 (2007): 646–67, https://doi.org/10.1016/J.MAM.2007.06.001.↩︎

26. Aminah Khalid et al., “Role of Vitamin C in Skin Aging Mechanism-A Narrative Review,” Journal of Health and Rehabilitation Research, 2024, https://doi.org/10.61919/jhrr.v4i2.1078; Juliet M. Pullar, Anitra C. Carr, and Margreet C. M. Vissers, “The Roles of Vitamin C in Skin Health,” Nutrients 9, no. 8 (August 12, 2017): 866, https://doi.org/10.3390/nu9080866; Jae-Hong Jeong et al., “Inhibitory Effect of Vitamin C on Intrinsic Aging in Human Dermal Fibroblasts and Hairless Mice,” Food Science and Biotechnology 27 (2017): 555–64, https://doi.org/10.1007/s10068-017-0252-6.↩︎

27. Kari I. Kivirikko and Darwin J. Prockop, “ENZYMATIC HYDROXYLATION OF PROLINE AND LYSINE IN PROTOCOLLAGEN*,” Proceedings of the National Academy of Sciences of the United States of America 57, no. 3 (March 1967): 782–89.↩︎

28. Joel Rosenbloom, Margaret Harsch, and Sergio Jimenez, “Hydroxyproline Content Determines the Denaturation Temperature of Chick Tendon Collagen,” Archives of Biochemistry and Biophysics 158, no. 2 (October 1, 1973): 478–84, https://doi.org/10.1016/0003-9861(73)90539-0.↩︎

29. Jeffrey C. Geesin et al., “Ascorbic Acid Specifically Increases Type I and Type III Procollagen Messenger RNA Levels in Human Skin Fibroblasts,” Journal of Investigative Dermatology 90, no. 4 (April 1988): 420–24, https://doi.org/10.1111/1523-1747.ep12460849.↩︎

30. B. Nusgens et al., “Topically Applied Vitamin C Enhances the mRNA Level of Collagens I and III, Their Processing Enzymes and Tissue Inhibitor of Matrix Metalloproteinase 1 in the Human Dermis.,” The Journal of Investigative Dermatology 116 6 (2001): 853–59, https://doi.org/10.1046/J.0022-202X.2001.01362.X; F. Pfeffer et al., “Modulation of 72-Kilodalton Type IV Collagenase (Matrix Metalloproteinase-2) by Ascorbic Acid in Cultured Human Amnion-Derived Cells.,” Biology of Reproduction 59 2 (1998): 326–29, https://doi.org/10.1095/BIOLREPROD59.2.326.↩︎

31. A. Lauer et al., “Dose-Dependent Vitamin C Uptake and Radical Scavenging Activity in Human Skin Measured with in Vivo Electron Paramagnetic Resonance Spectroscopy,” Skin Pharmacology and Physiology 26 (2013): 147–54, https://doi.org/10.1159/000350833; Francis McArdle et al., “UVR-Induced Oxidative Stress in Human Skin in Vivo: Effects of Oral Vitamin C Supplementation.,” Free Radical Biology & Medicine 33 10 (2002): 1355–62, https://doi.org/10.1016/S0891-5849(02)01042-0.↩︎

32. J. Pincemail and S. Meziane, “On the Potential Role of the Antioxidant Couple Vitamin E/Selenium Taken by the Oral Route in Skin and Hair Health,” Antioxidants 11 (2022), https://doi.org/10.3390/antiox11112270; F. Nachbar and H. Korting, “The Role of Vitamin E in Normal and Damaged Skin,” Journal of Molecular Medicine 73 (2004): 7–17, https://doi.org/10.1007/BF00203614.↩︎

33. Omid Asbaghi et al., “The Effect of Vitamin E Supplementation on Selected Inflammatory Biomarkers in Adults: A Systematic Review and Meta-Analysis of Randomized Clinical Trials,” Scientific Reports 10 (October 14, 2020): 17234, https://doi.org/10.1038/s41598-020-73741-6.↩︎

34. Nur Izyani Ghazali et al., “Effects of Tocotrienol on Aging Skin: A Systematic Review,” Frontiers in Pharmacology 13 (2022), https://doi.org/10.3389/fphar.2022.1006198.↩︎

35. Madison K. Cook, Patrick O. Perche, and Steven R. Feldman, “The Use of Oral Vitamin A in Acne Management: A Review,” Dermatology Online Journal 28, no. 5 (October 15, 2022), https://doi.org/10.5070/D328559239.↩︎

36. T. E. Moon et al., “Effect of Retinol in Preventing Squamous Cell Skin Cancer in Moderate-Risk Subjects: A Randomized, Double-Blind, Controlled Trial. Southwest Skin Cancer Prevention Study Group,” Cancer Epidemiology, Biomarkers & Prevention: A Publication of the American Association for Cancer Research, Cosponsored by the American Society of Preventive Oncology 6, no. 11 (November 1997): 949–56.↩︎

37. D. Alberts et al., “Safety and Efficacy of Dose-Intensive Oral Vitamin A in Subjects with Sun-Damaged Skin,” Clinical Cancer Research 10 (2004): 1875–80, https://doi.org/10.1158/1078-0432.CCR-03-0188.↩︎

38. Massimo Milani and Francesca Colombo, “Skin Anti-Aging Effect of Oral Vitamin A Supplementation in Combination with Topical Retinoic Acid Treatment in Comparison with Topical Treatment Alone: A Randomized, Prospective, Assessor-Blinded, Parallel Trial,” Cosmetics 10, no. 5 (October 2023): 144, https://doi.org/10.3390/cosmetics10050144.↩︎

39. Maeve C Cosgrove et al., “Dietary Nutrient Intakes and Skin-Aging Appearance among Middle-Aged American Women,” The American Journal of Clinical Nutrition 86, no. 4 (October 2007): 1225–31, https://doi.org/10.1093/ajcn/86.4.1225.↩︎

40. M. B. Purba et al., “Skin Wrinkling: Can Food Make a Difference?,” Journal of the American College of Nutrition 20, no. 1 (February 2001): 71–80, https://doi.org/10.1080/07315724.2001.10719017.↩︎

41. Flavia Addor, Juliana Cotta Vieira, and Camila Abreu, “Improvement of Dermal Parameters in Aged Skin after Oral Use of a Nutrient Supplement,” Clinical, Cosmetic and Investigational Dermatology Volume 11 (April 2018): 195–201, https://doi.org/10.2147/CCID.S150269.↩︎

42. Gregory Shaw et al., “Vitamin C–Enriched Gelatin Supplementation before Intermittent Activity Augments Collagen Synthesis,” The American Journal of Clinical Nutrition 105, no. 1 (January 2017): 136–43, https://doi.org/10.3945/ajcn.116.138594.↩︎

43. Lauer et al., “Dose-Dependent Vitamin C Uptake and Radical Scavenging Activity in Human Skin Measured with in Vivo Electron Paramagnetic Resonance Spectroscopy.”↩︎

44. Eliana Barbosa et al., “Supplementation of Vitamin E, Vitamin C, and Zinc Attenuates Oxidative Stress in Burned Children: A Randomized, Double-Blind, Placebo-Controlled Pilot Study,” Journal of Burn Care & Research 30, no. 5 (September 1, 2009): 859–66, https://doi.org/10.1097/BCR.0b013e3181b487a8.↩︎

45. Seung Jin Lee et al., “Long- and Short-Term Effects of Vitamin E Administration along with Stress on Skin Tissues of Mice,” Journal of the Korean Society for Applied Biological Chemistry 55 (2012): 105–9, https://doi.org/10.1007/s13765-012-0018-z.↩︎

46. Ghazali et al., “Effects of Tocotrienol on Aging Skin.”↩︎

47. “Office of Dietary Supplements – Vitamin A and Carotenoids.”↩︎

48. Pullar, Carr, and Vissers, “The Roles of Vitamin C in Skin Health”; “Vitamin C – Health Professional Fact Sheet,” accessed January 14, 2025, https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/.↩︎

49. Barbosa et al., “Supplementation of Vitamin E, Vitamin C, and Zinc Attenuates Oxidative Stress in Burned Children.”↩︎

50. Pullar, Carr, and Vissers, “The Roles of Vitamin C in Skin Health.”↩︎

51. “Office of Dietary Supplements – Vitamin E,” accessed December 15, 2024, https://ods.od.nih.gov/factsheets/VitaminE-HealthProfessional/.↩︎

52. “Office of Dietary Supplements – Vitamin A and Carotenoids.”↩︎

53. “Vitamin A,” Linus Pauling Institute, April 22, 2014, https://lpi.oregonstate.edu/mic/vitamins/vitamin-A.↩︎

54. “Supplemental Forms,” Linus Pauling Institute, October 21, 2014, https://lpi.oregonstate.edu/mic/vitamins/vitamin-C/supplemental-forms.↩︎

55. Anitra C. Carr et al., “A Randomized Steady-State Bioavailability Study of Synthetic versus Natural (Kiwifruit-Derived) Vitamin C,” Nutrients 5, no. 9 (September 17, 2013): 3684–95, https://doi.org/10.3390/nu5093684.↩︎

56. K. Cheng et al., “A Comparison of Natural (D-α-Tocopherol) and Synthetic (DL-α-Tocopherol Acetate) Vitamin E Supplementation on the Growth Performance, Meat Quality and Oxidative Status of Broilers,” Asian-Australasian Journal of Animal Sciences 29, no. 5 (May 2016): 681–88, https://doi.org/10.5713/ajas.15.0819.↩︎

57. “Vitamin A,” Mayo Clinic, accessed December 13, 2024, https://www.mayoclinic.org/drugs-supplements-vitamin-a/art-20365945; “Office of Dietary Supplements – Vitamin E”; “Office of Dietary Supplements – Vitamin C,” accessed November 26, 2024, https://ods.od.nih.gov/factsheets/VitaminC-Consumer/; “Office of Dietary Supplements – Vitamin A and Carotenoids.”↩︎

58. “Office of Dietary Supplements – Vitamin C,” accessed December 8, 2024, https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/.↩︎

59. “Office of Dietary Supplements – Vitamin E.”↩︎

60. “Office of Dietary Supplements – Vitamin A and Carotenoids.”↩︎

61. H. Gerster, “Can Adults Adequately Convert Alpha-Linolenic Acid (18:3n-3) to Eicosapentaenoic Acid (20:5n-3) and Docosahexaenoic Acid (22:6n-3)?,” International Journal for Vitamin and Nutrition Research. Internationale Zeitschrift Fur Vitamin- Und Ernahrungsforschung. Journal International De Vitaminologie Et De Nutrition 68, no. 3 (1998): 159–73; Graham C. Burdge and Philip C. Calder, “Conversion of Alpha-Linolenic Acid to Longer-Chain Polyunsaturated Fatty Acids in Human Adults,” Reproduction, Nutrition, Development 45, no. 5 (2005): 581–97, https://doi.org/10.1051/rnd:2005047.↩︎

62. Asmaa S. Abdelhamid et al., “Omega‐3 Fatty Acids for the Primary and Secondary Prevention of Cardiovascular Disease – Abdelhamid, AS – 2020 | Cochrane Library,” accessed December 16, 2024, https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD003177.pub5/full; F. Cartolano et al., “Omega-3 Fatty Acids Improve Functionality of High-Density Lipoprotein in Individuals With High Cardiovascular Risk: A Randomized, Parallel, Controlled and Double-Blind Clinical Trial,” Frontiers in Nutrition 8 (2022), https://doi.org/10.3389/fnut.2021.767535; Danielle Swanson, R. Block, and S. Mousa, “Omega-3 Fatty Acids EPA and DHA: Health Benefits throughout Life.,” Advances in Nutrition 3 1 (2012): 1–7, https://doi.org/10.3945/an.111.000893; Fereidoon Shahidi and Priyatharini Ambigaipalan, “Omega-3 Polyunsaturated Fatty Acids and Their Health Benefits,” Annual Review of Food Science and Technology 9, no. 1 (March 25, 2018): 345–81, https://doi.org/10.1146/annurev-food-111317-095850.↩︎

63. Philip C. Calder, “Omega-3 Fatty Acids and Inflammatory Processes: From Molecules to Man,” Biochemical Society Transactions 45, no. 5 (October 15, 2017): 1105–15, https://doi.org/10.1042/BST20160474.↩︎

64. Calder.↩︎

65. Suzanne M. Pilkington et al., “Omega-3 Polyunsaturated Fatty Acids: Photoprotective Macronutrients,” Experimental Dermatology 20, no. 7 (2011): 537–43, https://doi.org/10.1111/j.1600-0625.2011.01294.x.↩︎

66. Bryce J. Thomsen, Eunice Y. Chow, and M. Sapijaszko, “The Potential Uses of Omega-3 Fatty Acids in Dermatology: A Review,” Journal of Cutaneous Medicine and Surgery 24 (2020): 481–94, https://doi.org/10.1177/1203475420929925.↩︎

67. Jae Yoon Jung et al., “Effect of Dietary Supplementation with Omega-3 Fatty Acid and Gamma-Linolenic Acid on Acne Vulgaris: A Randomised, Double-Blind, Controlled Trial,” Acta Dermato-Venereologica 94, no. 5 (January 29, 2014): 521–25, https://doi.org/10.2340/00015555-1802.↩︎

68. Julie Latreille et al., “Association between Dietary Intake of N-3 Polyunsaturated Fatty Acids and Severity of Skin Photoaging in a Middle-Aged Caucasian Population,” Journal of Dermatological Science 72, no. 3 (December 2013): 233–39, https://doi.org/10.1016/j.jdermsci.2013.07.006.↩︎

69. Silke De Spirt et al., “Intervention with Flaxseed and Borage Oil Supplements Modulates Skin Condition in Women,” The British Journal of Nutrition 101, no. 3 (February 2009): 440–45, https://doi.org/10.1017/S0007114508020321.↩︎

70. Thomsen, Chow, and Sapijaszko, “The Potential Uses of Omega-3 Fatty Acids in Dermatology.”↩︎

71. Lesley E. Rhodes et al., “Effect of Eicosapentaenoic Acid, an Omega-3 Polyunsaturated Fatty Acid, on UVR-Related Cancer Risk in Humans. An Assessment of Early Genotoxic Markers,” Carcinogenesis 24, no. 5 (May 1, 2003): 919–25, https://doi.org/10.1093/carcin/bgg038.↩︎

72. Kyoko Miura et al., “Omega-3 Fatty Acid Supplement Skin Cancer Prophylaxis in Lung Transplant Recipients: A Randomized, Controlled Pilot Trial,” The Journal of Heart and Lung Transplantation 38, no. 1 (January 1, 2019): 59–65, https://doi.org/10.1016/j.healun.2018.09.009.↩︎

73. Katina Handeland, Mike Wakeman, and Lena Burri, “Krill Oil Supplementation Improves Transepidermal Water Loss, Hydration and Elasticity of the Skin in Healthy Adults: Results from Two Randomized, Double-Blind, Placebo-Controlled, Dose-Finding Pilot Studies.,” Journal of Cosmetic Dermatology, 2024, https://doi.org/10.1111/jocd.16513.↩︎

74. M. Alrasheed et al., “Improving Skin Hardness and Thickness Using a Combination of Omega-3 Fatty Acid and Aloe Vera Oil: Pilot Study” 3 (2020): 60–64, https://doi.org/10.21608/jabps.2020.21568.1065.↩︎

75. James J. DiNicolantonio and James O’Keefe, “The Importance of Maintaining a Low Omega-6/Omega-3 Ratio for Reducing the Risk of Autoimmune Diseases, Asthma, and Allergies,” Missouri Medicine 118, no. 5 (2021): 453–59.↩︎

76. “Tolerable Upper Intake Level of EPA, DHA and DPA | EFSA,” July 27, 2012, https://www.efsa.europa.eu/en/efsajournal/pub/2815.↩︎

77. Breanne M Anderson and David WL Ma, “Are All N-3 Polyunsaturated Fatty Acids Created Equal?,” Lipids in Health and Disease 8 (August 10, 2009): 33, https://doi.org/10.1186/1476-511X-8-33.↩︎

78. Anderson and Ma.↩︎

79. Sepideh Alijani et al., “Bioavailability of EPA and DHA in Humans – A Comprehensive Review,” Progress in Lipid Research 97 (January 1, 2025): 101318, https://doi.org/10.1016/j.plipres.2024.101318.↩︎

80. Anderson and Ma, “Are All N-3 Polyunsaturated Fatty Acids Created Equal?”↩︎

81. “Office of Dietary Supplements – Omega-3 Fatty Acids,” accessed December 16, 2024, https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/.↩︎

82. H Tapiero et al., “Polyphenols: Do They Play a Role in the Prevention of Human Pathologies?,” Biomedicine & Pharmacotherapy 56, no. 4 (June 1, 2002): 200–207, https://doi.org/10.1016/S0753-3322(02)00178-6; S. Luca et al., “Bioactivity of Dietary Polyphenols: The Role of Metabolites,” Critical Reviews in Food Science and Nutrition 60 (2020): 626–59, https://doi.org/10.1080/10408398.2018.1546669.↩︎

83. Anna Ratz-Łyko et al., “Influence of Polyphenols on the Physiological Processes in the Skin,” Phytotherapy Research 29 (2015): 509–17, https://doi.org/10.1002/ptr.5289.↩︎

84. Deepti Dwevedi and Ankur Srivastava, “Molecular Mechanisms of Polyphenols in Management of Skin Aging.,” Current Aging Science 17 3 (2024): 180–88, https://doi.org/10.2174/0118746098287130240212085507.↩︎

85. Mang-Lang Sun et al., “Effects of Natural Polyphenols on Skin and Hair Health: A Review,” Molecules 27 (2022), https://doi.org/10.3390/molecules27227832.↩︎

86. Erika Csekes and L. Račková, “Skin Aging, Cellular Senescence and Natural Polyphenols,” International Journal of Molecular Sciences 22 (2021), https://doi.org/10.3390/ijms222312641; J. A. Nichols and S. Katiyar, “Skin Photoprotection by Natural Polyphenols: Anti-Inflammatory, Antioxidant and DNA Repair Mechanisms,” Archives of Dermatological Research 302 (2010): 71–83, https://doi.org/10.1007/s00403-009-1001-3.↩︎

87. Victoria A. Nash et al., “The Effects of Grape and Red Wine Polyphenols on Gut Microbiota – A Systematic Review.,” Food Research International 113 (2018): 277–87, https://doi.org/10.1016/j.foodres.2018.07.019; Guiling Ma and Yanting Chen, “Polyphenol Supplementation Benefits Human Health via Gut Microbiota: A Systematic Review via Meta-Analysis,” Journal of Functional Foods 66 (2020), https://doi.org/10.1016/j.jff.2020.103829.↩︎

88. T. A. Corrêa et al., “The Two-Way Polyphenols-Microbiota Interactions and Their Effects on Obesity and Related Metabolic Diseases,” Frontiers in Nutrition 6 (2019), https://doi.org/10.3389/fnut.2019.00188; M. I. Queipo-Ortuño et al., “Influence of Red Wine Polyphenols and Ethanol on the Gut Microbiota Ecology and Biochemical Biomarkers.,” The American Journal of Clinical Nutrition 95 6 (2012): 1323–34, https://doi.org/10.3945/ajcn.111.027847; Yiying Zhao and Q. Jiang, “Roles of the Polyphenol-Gut Microbiota Interaction in Alleviating Colitis and Preventing Colitis-Associated Colorectal Cancer.,” Advances in Nutrition, 2020, https://doi.org/10.1093/advances/nmaa104.↩︎

89. T. Shoji et al., “Administration of Apple Polyphenol Supplements for Skin Conditions in Healthy Women: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial,” Nutrients 12 (2020), https://doi.org/10.3390/nu12041071.↩︎

90. L. Christman et al., “Polyphenol-Rich Cranberry Beverage Positively Affected Skin Health, Skin Lipids, Skin Microbiome, Inflammation, and Oxidative Stress in Women in a Randomized Controlled Trial,” Nutrients 16 (2024), https://doi.org/10.3390/nu16183126.↩︎

91. Qian Sun et al., “Effectiveness of Dietary Supplement for Skin Moisturizing in Healthy Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials,” Frontiers in Nutrition 9 (June 2, 2022), https://doi.org/10.3389/fnut.2022.895192.↩︎

92. U. Heinrich et al., “Green Tea Polyphenols Provide Photoprotection, Increase Microcirculation, and Modulate Skin Properties of Women.,” The Journal of Nutrition 141 6 (2011): 1202–8, https://doi.org/10.3945/jn.110.136465.↩︎

93. C. Del Bo’ et al., “Systematic Review on Polyphenol Intake and Health Outcomes: Is There Sufficient Evidence to Define a Health-Promoting Polyphenol-Rich Dietary Pattern?,” Nutrients 11 (2019), https://doi.org/10.3390/nu11061355.↩︎

94. Luana Alberti Noronha et al., “Dietary Polyphenols: What Is the Estimated Intake in Population Studies With Adults and Elderly People?,” Current Nutrition Reports 13, no. 2 (June 1, 2024): 280–93, https://doi.org/10.1007/s13668-024-00530-2.↩︎

95. Keith R. Martin, “Polyphenols as Dietary Supplements: A Double-Edged Sword,” Nutrition and Dietary Supplements, December 2009, 1, https://doi.org/10.2147/NDS.S6422.↩︎

96. Louise I. Mennen et al., “Risks and Safety of Polyphenol Consumption,” The American Journal of Clinical Nutrition 81, no. 1 Suppl (January 2005): 326S-329S, https://doi.org/10.1093/ajcn/81.1.326S.↩︎

97. Martin, “Polyphenols as Dietary Supplements.”↩︎

98. A. Bertelli et al., “Polyphenols: From Theory to Practice,” Foods 10 (2021), https://doi.org/10.3390/foods10112595.↩︎

99. Mang Sun et al., “Effects of Natural Polyphenols on Skin and Hair Health: A Review,” Molecules 27, no. 22 (November 14, 2022): 7832, https://doi.org/10.3390/molecules27227832.↩︎

100. Mohammad Aatif, “Current Understanding of Polyphenols to Enhance Bioavailability for Better Therapies,” Biomedicines 11, no. 7 (July 24, 2023): 2078, https://doi.org/10.3390/biomedicines11072078.↩︎

101. Aatif.↩︎

102. Martin, “Polyphenols as Dietary Supplements.”↩︎

103. Payman Raise-Abdullahi et al., “Natural Polyphenols as Therapeutic Candidates for Mitigating Neuropsychiatric Symptoms in Post-Traumatic Stress Disorder: Evidence from Preclinical Studies,” Progress in Neuro-Psychopharmacology and Biological Psychiatry 136 (January 10, 2025): 111230, https://doi.org/10.1016/j.pnpbp.2024.111230; Aleksandra Duda-Chodak and Tomasz Tarko, “Possible Side Effects of Polyphenols and Their Interactions with Medicines,” Molecules 28, no. 6 (March 10, 2023): 2536, https://doi.org/10.3390/molecules28062536.↩︎

104. “Green Tea Information | Mount Sinai – New York,” accessed February 3, 2025, https://www.mountsinai.org/health-library/herb/green-tea; Karen L. Posey, “Curcumin and Resveratrol: Nutraceuticals with so Much Potential for Pseudoachondroplasia and Other ER-Stress Conditions,” Biomolecules 14, no. 2 (January 27, 2024): 154, https://doi.org/10.3390/biom14020154.↩︎

105. Mrinal Gupta et al., “Zinc Therapy in Dermatology: A Review,” Dermatology Research and Practice 2014 (2014): 709152, https://doi.org/10.1155/2014/709152; R. Rucker et al., “Copper, Lysyl Oxidase, and Extracellular Matrix Protein Cross-Linking.,” The American Journal of Clinical Nutrition 67 5 Suppl (1998): 996–1002, https://doi.org/10.1093/ajcn/67.5.996S; Marek Haftek, Rawad Abdayem, and Pascale Guyonnet-Debersac, “Skin Minerals: Key Roles of Inorganic Elements in Skin Physiological Functions,” International Journal of Molecular Sciences 23, no. 11 (January 2022): 6267, https://doi.org/10.3390/ijms23116267.↩︎

106. Elizabeth F. Rostan et al., “Evidence Supporting Zinc as an Important Antioxidant for Skin,” International Journal of Dermatology 41, no. 9 (September 2002): 606–11, https://doi.org/10.1046/j.1365-4362.2002.01567.x.↩︎

107. S. Navarro et al., “Role of Zinc in the Process of Pancreatic Fibrosis in Chronic Alcoholic Pancreatitis,” Pancreas 9 (1994), https://doi.org/10.1097/00006676-199403000-00020.↩︎

108. Gupta et al., “Zinc Therapy in Dermatology.”↩︎

109. Rucker et al., “Copper, Lysyl Oxidase, and Extracellular Matrix Protein Cross-Linking.”↩︎

110. “Undetectable Intracellular Free Copper: The Requirement of a Copper Chaperone for Superoxide Dismutase. – Consensus,” accessed January 3, 2025, https://consensus.app/papers/undetectable-intracellular-free-copper-the-requirement-rae-schmidt/2246fe7854895ce59d5e3cad71ebce6e/; M. J. Lee et al., “Extracellular Superoxide Dismutase Prevents Skin Aging by Promoting Collagen Production via Activation of AMPK and Nrf2/HO-1 Cascades.,” The Journal of Investigative Dermatology, 2021, https://doi.org/10.1016/j.jid.2021.02.757.↩︎

111. Wenlin Yuan, S. Burleigh, and J. Dawson, “Melanin Biosynthesis by Frankia Strain CeI5.,” Physiologia Plantarum 131 2 (2007): 180–90, https://doi.org/10.1111/j.1399-3054.2007.00948.x; J. Menter et al., “Photoprotection of Mammalian Acid‐Soluble Collagen by Cuttlefish Sepia Melanin In Vitro,” Photochemistry and Photobiology 68 (1998), https://doi.org/10.1111/j.1751-1097.1998.tb02510.x.↩︎

112. Haftek, Abdayem, and Guyonnet-Debersac, “Skin Minerals”; Maria V. Sankova et al., “Magnesium Deficiency and Its Interaction with the Musculoskeletal System, Exercise, and Connective Tissue: An Evidence Synthesis,” Sport Sciences for Health 20, no. 3 (September 1, 2024): 715–26, https://doi.org/10.1007/s11332-024-01179-8.↩︎

113. Elham Rahmanian et al., “The Effect of Topical Magnesium on Healing of Pre-Clinical Burn Wounds,” Burns 50, no. 3 (April 1, 2024): 630–40, https://doi.org/10.1016/j.burns.2023.10.015.↩︎

114. Sumel Ashique et al., “A Narrative Review on the Role of Magnesium in Immune Regulation, Inflammation, Infectious Diseases, and Cancer,” Journal of Health, Population, and Nutrition 42 (July 27, 2023): 74, https://doi.org/10.1186/s41043-023-00423-0.↩︎

115. A. Nunes et al., “Magnesium Activates Microsecond Dynamics to Regulate Integrin-Collagen Recognition.,” Structure 26 8 (2018): 1080–10905, https://doi.org/10.1016/j.str.2018.05.010.↩︎

116. G. P. Barron, P. B. Pearson, and S. O. Brown, “Magnesium Deficiency in the Sexually Mature Rat.,” Proceedings of the Society for Experimental Biology and Medicine 69, no. 1 (October 1, 1948): 128–30, https://doi.org/10.3181/00379727-69-16639.↩︎

117. G. Lipkin, C. March, and J. Gowdey, “MAGNESIUM IN EPIDERMIS, DERMIS, AND WHOLE SKIN OF NORMAL AND ATOPIC SUBJECTS.,” The Journal of Investigative Dermatology 42 (1964): 293–304, https://doi.org/10.1038/JID.1964.69.↩︎

118. A. R. Vaughn et al., “Micronutrients in Atopic Dermatitis: A Systematic Review.,” Journal of Alternative and Complementary Medicine 25 6 (2019): 567–77, https://doi.org/10.1089/acm.2018.0363.↩︎

119. Ehrhardt Proksch et al., “Bathing in a Magnesium-Rich Dead Sea Salt Solution Improves Skin Barrier Function, Enhances Skin Hydration, and Reduces Inflammation in Atopic Dry Skin,” International Journal of Dermatology 44, no. 2 (2005): 151–57, https://doi.org/10.1111/j.1365-4632.2005.02079.x.↩︎

120. Elham Rahmanian et al., “The Effect of Topical Magnesium on Healing of Pre-Clinical Burn Wounds,” Burns 50, no. 3 (April 1, 2024): 630–40, https://doi.org/10.1016/j.burns.2023.10.015.↩︎

121. Aleksandra Podgórska et al., “Zinc, Copper, and Iron in Selected Skin Diseases,” International Journal of Molecular Sciences 25, no. 7 (January 2024): 3823, https://doi.org/10.3390/ijms25073823.↩︎

122. Jeffrey Alex Varghese et al., “Acquired Perforating Dermatosis in Patients with Copper Deficiency,” JAAD Case Reports 15 (July 27, 2021): 110–14, https://doi.org/10.1016/j.jdcr.2021.07.017.↩︎

123. R. DiSilvestro, Joshua T. Selsby, and K. Siefker, “A Pilot Study of Copper Supplementation Effects on Plasma F2alpha Isoprostanes and Urinary Collagen Crosslinks in Young Adult Women.,” Journal of Trace Elements in Medicine and Biology : Organ of the Society for Minerals and Trace Elements 24 3 (2010): 165–68, https://doi.org/10.1016/j.jtemb.2010.02.003.↩︎

124. Mohammed Al Abadie et al., “Possible Relationship between Poor Skin Disorders Prognosis and Serum Zinc Level: A Narrative Review,” Dermatology Reports 14, no. 4 (July 6, 2022): 9512, https://doi.org/10.4081/dr.2022.9512.↩︎

125. Simran Dhaliwal et al., “Effects of Zinc Supplementation on Inflammatory Skin Diseases: A Systematic Review of the Clinical Evidence,” American Journal of Clinical Dermatology 21, no. 1 (February 1, 2020): 21–39, https://doi.org/10.1007/s40257-019-00484-0.↩︎

126. “Office of Dietary Supplements – Copper,” accessed January 3, 2025, https://ods.od.nih.gov/factsheets/Copper-HealthProfessional/.↩︎

127. DiSilvestro, Selsby, and Siefker, “A Pilot Study of Copper Supplementation Effects on Plasma F2alpha Isoprostanes and Urinary Collagen Crosslinks in Young Adult Women.”↩︎

128. “Office of Dietary Supplements – Zinc,” accessed January 3, 2025, https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/.↩︎

129. “Office of Dietary Supplements – Magnesium,” accessed January 3, 2025, https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/.↩︎

130. “Office of Dietary Supplements – Copper.”↩︎

131. “Office of Dietary Supplements – Zinc.”↩︎

132. “Office of Dietary Supplements – Copper.”↩︎

133. “Office of Dietary Supplements – Magnesium.”↩︎

134. Yan Gao et al., “Biomedical Applications of Aloe Vera,” Critical Reviews in Food Science and Nutrition 59 (2018): 244–56, https://doi.org/10.1080/10408398.2018.1496320.↩︎

135. Davood Hekmatpou et al., “The Effect of Aloe Vera Clinical Trials on Prevention and Healing of Skin Wound: A Systematic Review,” Iranian Journal of Medical Sciences 44, no. 1 (January 2019): 1–9.↩︎

136. Gao et al., “Biomedical Applications of Aloe Vera.”↩︎

137. Miyuki Tanaka et al., “Effects of Aloe Sterol Supplementation on Skin Elasticity, Hydration, and Collagen Score: A 12-Week Double-Blind, Randomized, Controlled Trial,” Skin Pharmacology and Physiology 29 (2017): 309–17, https://doi.org/10.1159/000454718.↩︎

138. E. Barrantes and M. Guinea, “Inhibition of Collagenase and Metalloproteinases by Aloins and Aloe Gel.,” Life Sciences 72 7 (2003): 843–50, https://doi.org/10.1016/S0024-3205(02)02308-1.↩︎

139. Hekmatpou et al., “The Effect of Aloe Vera Clinical Trials on Prevention and Healing of Skin Wound.”↩︎

140. Rashi Agrawal, Anne Hu, and Wendy B. Bollag, “The Skin and Inflamm-Aging,” Biology 12, no. 11 (November 2, 2023): 1396, https://doi.org/10.3390/biology12111396.↩︎

141. Amar Surjushe, Resham Vasani, and D G Saple, “ALOE VERA: A SHORT REVIEW,” Indian Journal of Dermatology 53, no. 4 (2008): 163–66, https://doi.org/10.4103/0019-5154.44785.↩︎

142. A. Yagi et al., “Antioxidant, Free Radical Scavenging and Anti-Inflammatory Effects of Aloesin Derivatives in Aloe Vera,” Planta Medica 68 (November 26, 2002): 957–60, https://doi.org/10.1055/s-2002-35666.↩︎

143. Soyun Cho et al., “Dietary Aloe Vera Supplementation Improves Facial Wrinkles and Elasticity and It Increases the Type I Procollagen Gene Expression in Human Skin in Vivo,” Annals of Dermatology 21, no. 1 (February 2009): 6–11, https://doi.org/10.5021/ad.2009.21.1.6.↩︎

144. Miyuki Tanaka et al., “Effects of Aloe Sterol Supplementation on Skin Elasticity, Hydration, and Collagen Score: A 12-Week Double-Blind, Randomized, Controlled Trial,” Skin Pharmacology and Physiology 29 (2017): 309–17, https://doi.org/10.1159/000454718.↩︎

145. C. Kaminaka et al., “Effects of Low‐dose Aloe Sterol Supplementation on Skin Moisture, Collagen Score and Objective or Subjective Symptoms: 12‐week, Double‐blind, Randomized Controlled Trial,” The Journal of Dermatology 47 (2020): 998–1006, https://doi.org/10.1111/1346-8138.15428.↩︎

146. Marie Saito et al., “Oral Administration of Aloe Vera Gel Powder Prevents UVB-Induced Decrease in Skin Elasticity via Suppression of Overexpression of MMPs in Hairless Mice,” Bioscience, Biotechnology, and Biochemistry 80, no. 7 (July 2, 2016): 1416–24, https://doi.org/10.1080/09168451.2016.1156480.↩︎

147. Cho et al., “Dietary Aloe Vera Supplementation Improves Facial Wrinkles and Elasticity and It Increases the Type I Procollagen Gene Expression in Human Skin in Vivo”; Tanaka et al., “Effects of Aloe Sterol Supplementation on Skin Elasticity, Hydration, and Collagen Score,” 2017; Kaminaka et al., “Effects of Low‐dose Aloe Sterol Supplementation on Skin Moisture, Collagen Score and Objective or Subjective Symptoms.”↩︎

148. S. Kwack, Kyu Bong Kim, and B. Lee, “Estimation of Tolerable Upper Intake Level (UL) of Active Aloe,” Journal of Toxicology and Environmental Health, Part A 72 (2009): 1455–62, https://doi.org/10.1080/15287390903212931.↩︎

149. Xiaoqing Guo and Nan Mei, “Aloe Vera: A Review of Toxicity and Adverse Clinical Effects,” Journal of Environmental Science and Health. Part C, Environmental Carcinogenesis & Ecotoxicology Reviews 34, no. 2 (April 2, 2016): 77–96, https://doi.org/10.1080/10590501.2016.1166826.↩︎

150. Gao et al., “Biomedical Applications of Aloe Vera.”↩︎

151. “Aloe,” Mayo Clinic, accessed January 9, 2025, https://www.mayoclinic.org/drugs-supplements-aloe/art-20362267.↩︎

152. Guo and Mei, “Aloe Vera.”↩︎

153. “Aloe.”↩︎

154. “Aloe Information | Mount Sinai – New York,” Mount Sinai Health System, accessed February 19, 2025, https://www.mountsinai.org/health-library/herb/aloe.↩︎

155. “What Is the Mediterranean Diet?,” Cleveland Clinic, accessed March 18, 2025, https://my.clevelandclinic.org/health/articles/16037-mediterranean-diet.↩︎

156. Miguel A. Martínez-González et al., “Benefits of the Mediterranean Diet: Insights From the PREDIMED Study,” Progress in Cardiovascular Diseases, Preventive Cardiology Update: Controversy, Concensus, and Future Promise, 58, no. 1 (July 1, 2015): 50–60, https://doi.org/10.1016/j.pcad.2015.04.003.↩︎

157. Anne Guertler et al., “Exploring the Potential of Omega-3 Fatty Acids in Acne Patients: A Prospective Intervention Study,” Journal of Cosmetic Dermatology 23, no. 10 (2024): 3295–3304, https://doi.org/10.1111/jocd.16434.↩︎

158. Xiaoping Yu, Haomou Pu, and Margaret Voss, “Overview of Anti-Inflammatory Diets and Their Promising Effects on Non-Communicable Diseases,” The British Journal of Nutrition 132, no. 7 (n.d.): 898–918, https://doi.org/10.1017/S0007114524001405.↩︎

159. “Low-Glycemic Index Diet: What’s behind the Claims?,” Mayo Clinic, accessed March 18, 2025, https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/low-glycemic-index-diet/art-20048478.↩︎

160. Nazik H Hasrat and Asaad Q Al-Yassen, “The Relationship Between Acne Vulgaris and Insulin Resistance,” Cureus 15, no. 1 (n.d.): e34241, https://doi.org/10.7759/cureus.34241; Idris Adewale Ahmed and Maryam Abimbola Mikail, “Diet and Skin Health: The Good and the Bad,” Nutrition (Burbank, Los Angeles County, Calif.) 119 (March 2024): 112350, https://doi.org/10.1016/j.nut.2023.112350.↩︎

161. F. William Danby, “Nutrition and Aging Skin: Sugar and Glycation,” Clinics in Dermatology, Nutrition and the Skin: Part I, 28, no. 4 (July 1, 2010): 409–11, https://doi.org/10.1016/j.clindermatol.2010.03.018.↩︎

162. Raghad A Alarim et al., “Effects of the Ketogenic Diet on Glycemic Control in Diabetic Patients: Meta-Analysis of Clinical Trials,” Cureus 12, no. 10 (n.d.): e10796, https://doi.org/10.7759/cureus.10796; Axel Guilbaud et al., “How Can Diet Affect the Accumulation of Advanced Glycation End-Products in the Human Body?,” Foods 5, no. 4 (December 6, 2016): 84, https://doi.org/10.3390/foods5040084.↩︎

163. Lee Crosby et al., “Ketogenic Diets and Chronic Disease: Weighing the Benefits Against the Risks,” Frontiers in Nutrition 8 (July 16, 2021): 702802, https://doi.org/10.3389/fnut.2021.702802.↩︎

164. Lee et al., “Oral Intake of Collagen Peptide NS Improves Hydration, Elasticity, Desquamation, and Wrinkling in Human Skin”; Altgilbers et al., “A Biomimetic Combination of Actives Enhances Skin Hydration and Barrier Function via Modulation of Gene Expression.”↩︎

165. A. Tfayli et al., “Hydration Effects on the Barrier Function of Stratum Corneum Lipids: Raman Analysis of Ceramides 2, III and 5.,” The Analyst 138 21 (2013): 6582–88, https://doi.org/10.1039/c3an00604b.↩︎

166. Branchet Mc et al., “Morphometric Analysis of Dermal Collagen Fibers in Normal Human Skin as a Function of Age.,” Archives of Gerontology and Geriatrics 13 1 (1991): 1–14, https://doi.org/10.1016/0167-4943(91)90011-E.↩︎

167. “Collagen,” The Nutrition Source (blog), May 26, 2021, https://nutritionsource.hsph.harvard.edu/collagen/.↩︎

168. Thiele and Ekanayake-Mudiyanselage, “Vitamin E in Human Skin.”↩︎

169. Thiele, Hsieh, and Ekanayake-Mudiyanselage, “Vitamin E.”↩︎

170. Burdge and Calder, “Conversion of Alpha-Linolenic Acid to Longer-Chain Polyunsaturated Fatty Acids in Human Adults.”↩︎

171. Calder, “Omega-3 Fatty Acids and Inflammatory Processes.”↩︎

172. McArdle et al., “Effects of Oral Vitamin E and Beta-Carotene Supplementation on Ultraviolet Radiation-Induced Oxidative Stress in Human Skin.”↩︎

173. McArdle et al., “UVR-Induced Oxidative Stress in Human Skin in Vivo.”↩︎

174. Rhodes et al., “Effect of Eicosapentaenoic Acid, an Omega-3 Polyunsaturated Fatty Acid, on UVR-Related Cancer Risk in Humans. An Assessment of Early Genotoxic Markers.”↩︎