“You know. When I was a kid food was food. Before our scientific magicians poisoned the water, polluted the soil. Decimated plant and animal life. Why, in my day you could buy meat anywhere. Eggs, they had. Real butter. Fresh lettuce in the….”

Soylent Green, 1973

I am often asked my opinion regarding supplements like a daily multivitamin. I think that the answer depends on the individual and the circumstances. For example, prenatal vitamins with folic acid are an effective way to prevent neural tube defects in newborns. Yet excessive folic acid intake may be linked to an increased risk of certain cancers, such as colorectal, prostate, or breast cancer. Some studies have suggested that calcium supplementation, particularly when taken without vitamin D, may increase the risk of myocardial infarction in women by roughly 30%. Nature seems to prefer moderation mediated by ratios and charted by interconnections as opposed to hard absolutes and straightforward extremes. Whatever the case may be, I think it is a given that one cannot supplement their way to good health. If your diet is SAD (the Standard American Diet), there are no magic pills to transform chicken s**t into chicken salad.

But that doesn’t stop us from trying.

Roughly one in three American adults take a multivitamin with the goal of reducing disease susceptibility and increasing longevity [1],[2]. A study in 2022 by the US Preventative Services Task Force reviewed morbidity and mortality data from randomized clinical trials to address that goal and “found insufficient evidence for determining benefits or harms.” [3]

This week’s study spotlight takes a closer look at this practice with the simple question: does taking a daily multivitamin help us live longer?

The Study:

  • The review examined the data from three US prospective cohort studies consisting of a total of 390,124 generally healthy adults
  • The three studies were the National Institutes of Health–AARP Diet and Health Study (327,732 participants, 24 years of follow-up); the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (42,732 participants, 27 years of follow-up); and the Agricultural Health Study (19,660 participants, 26 years of follow-up).
  • The follow-up was more than 20 years, yielding 7,861,485 person-years of follow-up.

The Take-Away:

  • The median age was similar for daily multivitamin users versus nonusers, approximately 62 years of age.
  • Those who took multivitamins had a lower BMI and better diet quality.
  • Taking a daily multivitamin was not associated with a mortality benefit; in the pooled analysis, taking a daily multivitamin was associated with a trend towards a 4% increased risk of all-cause early mortality, but this was not statistically significant.

The Caveat:

This study examined a question plagued by two common confounders, both of which can often affect observational studies. The first is known as the “healthy user effect.” This is a phenomenon whereby individuals who engage in a particular healthy behavior or practice also tend to engage in other health-promoting behaviors. This can lead to what is known as a confounding bias in study results. The effect can result in making it appear that a health benefit is due to the study intervention when it might actually be due to the overall healthier lifestyle of the participants.

An example of this potential pitfall is reflected in the Hormone Replacement Therapy (HRT) trials. The first datasets were from observational studies. These suggested that HRT reduced the risk of cardiovascular disease in postmenopausal women. However, later randomized controlled trials showed no benefit and even potential harm. The difference in outcome was felt to be due to the healthy user effect in the early observational studies.

When considering dietary supplements like multivitamins, healthy user effects such as increased exercise, healthier diets, or less cigarette smoking could potentially skew results. Interestingly, in this particular analysis, the daily multivitamin users did, in fact, have a better diet quality but still had worse outcomes.

A second cofounder is known as the “sick user effect,” which is, in some ways, the opposite of the “healthy user effect.” In this scenario, what happens is that individuals who are already ill or have a higher risk of developing illnesses (or, in the case of this study, more likely to die) are more likely to use certain medications, interventions, medical services, or once again in the case of this study more likely to take a multivitamin in hopes of improving their health status. This can lead to confounding because the poor health outcomes observed could be wrongly attributed to the intervention when, in fact, the cause was the participants’ underlying health conditions. In the current study, an effort was made to address this, and this is why only healthy participants, those without a history of cancer or other chronic diseases, were enrolled.

In this study, there was no mortality benefit to taking a daily multivitamin regardless of the age group, whether the participants smoked cigarettes or not, ethnicity, BMI, or dietary habits. For an otherwise healthy person, the expense of a daily multivitamin supplement does not appear to increase longevity. For those with a history of cancer or other chronic diseases, the jury is still out with respect to the results from this study because that group of individuals was excluded from trial participation. Where the data is clear, is that you simply can’t go wrong with authentic, natural whole foods. To paraphrase the ancient Ayurvedic proverb, “When diet is wrong, supplements are of no use. When diet is correct, supplements are of no need.”


[1] (Kantor, 2016)

[2] (Cowan, 2018)

[3] (US Preventive Services Task Force, 2022)


The Study:

Loftfield E, O’Connell CP, Abnet CC, et al. Multivitamin Use and Mortality Risk in 3 Prospective US Cohorts. JAMA Netw Open. 2024;7(6):e2418729. doi:10.1001/jamanetworkopen.2024.18729


Additional resources:

Cowan AE, Jun S, Gahche JJ, Tooze JA, Dwyer JT, Eicher-Miller HA, Bhadra A, Guenther PM, Potischman N, Dodd KW, et al. Dietary Supplement Use Differs by Socioeconomic and Health-Related Characteristics among U.S. Adults, NHANES 2011–2014. Nutrients. 2018; 10(8):1114. https://doi.org/10.3390/nu10081114

Kantor ED, Rehm CD, Du M, White E, Giovannucci EL. Trends in Dietary Supplement Use Among US Adults From 1999-2012. JAMA. 2016;316(14):1464–1474. doi:10.1001/jama.2016.14403

US Preventive Services Task Force. Vitamin, Mineral, and Multivitamin Supplementation to Prevent Cardiovascular Disease and Cancer: US Preventive Services Task Force Recommendation Statement. JAMA. 2022;327(23):2326–2333. doi:10.1001/jama.2022.8970

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