Lately, everywhere I look, I am surrounded by protein; protein cereal, protein coffee, protein pasta. Protein everything.
Consuming a lot of protein daily brings a variety of health benefits, including weight loss and building tissue for muscle recovery. However, in all the rage for protein consumption, we are forgetting a less glamorous key element: fiber. Fiber is a vital nutrient for promoting women’s sexual and reproductive health.
A study published by the Interdisciplinary International Journal of the American Cancer Society in 2020 by Farvid et al., found that increasing fiber intake lowers the risk of breast cancer by 8-12 percent over all, and by 20 percent for premenopausal women in particular. In addition, a meta-analysis of more than 50 studies by He et al., (2025) found that every 5 grams of fiber added to the subjects’ diets reduced the risk of ovarian cancer by 3 percent.
What is fiber actually doing?
- Gut absorption and digestion: According to García‑Closas et al (2008), dietary fiber binds to excess estrogen and bile acids in the intestines, helping your body to excrete rather than reabsorb them.
- Insulin Control: Fiber intake has been generally linked to lower insulin levels and weight control.
- Anti-Inflammatory: Fiber consumption acts as an anti-inflammatory in the gut microbiome. When beneficial bacteria ferment fiber in your gut, they create through micro biomes found in fibre. These create short-chain fatty acids (SCFAs), which help to maintain gut barrier integrity,regulate immune responses, and reduce inflammation, which leads to a less inflamed uterus and gut, decreasing pain and tension every month.
- Estrogen Production Control: Foods such as vegetables, fruit, and legumes, that contain fiber usually also provide phytochemicals that act as anti-oxidants and hormone regulating compounds. For instance, according to a study published by Hu et al., in Nutrients 2023, when these phythochemicals are inhibited into the breast tissue, they work to ultimately block the ability of estrogen to produce malignant carcinogenic cells that turn into tumors.
The Estrogen-Endometriosis Connection
To put it simply, part of the uterine lining that you shed every month is the endometrium. Endometriosis is the condition that occurs when the endometrium grows outside the uterine walls and into the ovaries and other critical areas of the female reproductive system, causing inflammation and pain, especially during the luteal phase of the menstrual cycle.
Endometrial tissue grows primarily in response to increasing levels of estrogen, and dietary fiber helps regulate estrogen levels by binding to excess estrogen in the digestive tract and promoting its excretion. In fact, according to a study by Zheng et al., for the Scientific Reports Journal in 2024, a high fibre diet has been associated with reducing estrogen levels by about 10–25 percent, which, in turn, can lead to a reduction in endometrial tissue and so to a reduced risk of developing endometriosis.
While endometriosis remains an under-researched and under-funded condition, these findings are notable enough to promote fibre consumption for a healthier reproductive system.
How to include fiber in my food:
There are two types of fiber in food:
Soluble fibre can be dissolved in water and forms a gel-like consistency in your gut. It helps to improve digestion and lower cholesterol, acts as an anti-inflammatory and helps to reduce bloatingYou’ll mainly find this in oats, legumes, fruits, chia seeds, and flaxseeds.
Insoluble fibre is the type that speeds up your digestion and helps to move waste through your system. This is the one that leads to a decreased estrogen level and, like soluble fiber, it too has anti-inflammatory properties. You can find insoluble fiber in whole grains, nuts and seeds, and the skins of fruits.
Key takeaway: As long as you are consuming a healthy 25-30 or more grams of fiber daily, you are golden! Don’t get lost in micromanaging the types of fiber you’re consuming. Simply focus on a varied diet that includes cereals, fruits, and legumes and you’ll be consuming enough to make a difference in your long-term reproductive health.
References:
Abramiuk, M., Grywalska, E., Małkowska, P., Sierawska, O., Hrynkiewicz, R., & Niedźwiedzka-Rystwej, P. (2022). The role of the immune system in the development of endometriosis. Cells, 11(13), 2028. https://doi.org/10.3390/cells11132028
Burney, R. O., & Giudice, L. C. (2012). Pathogenesis and pathophysiology of endometriosis. Fertility and Sterility, 98(3), 511–519. https://doi.org/10.1016/j.fertnstert.2012.06.029
Carbone, J. W., & Pasiakos, S. M. (2019). Dietary Protein and Muscle Mass: Translating science to application and health benefit. Nutrients, 11(5), 1136. https://doi.org/10.3390/nu11051136
Daley, S. F., & Shreenath, A. P. (2025, December 1). The role of dietary fiber in health promotion and disease prevention: A practical guide for clinicians. StatPearls Publishing.
Dreher, M. L. (2017). Dietary fiber in health and disease. Humana Press.
Farvid, M. S., Spence, N. D., Holmes, M. D., & Barnett, J. B. (2020). Fiber consumption and breast cancer incidence: A systematic review and meta‐analysis of prospective studies. Cancer, 126(13), 3061–3075. https://doi.org/10.1002/cncr.32816
He, X., Hou, J., Liu, L., Chen, X., Zhang, L., & Pang, C. (2025). Dietary fiber consumption and outcomes of different cancers: an umbrella review. Food & Nutrition Research, 69. https://doi.org/10.29219/fnr.v69.11034
Hu, J., Wang, J., Li, Y., Xue, K., & Kan, J. (2023). Use of dietary fibers in reducing the risk of several cancer types: an umbrella review. Nutrients, 15(11), 2545. https://doi.org/10.3390/nu15112545
Pedersen, A. N., Kondrup, J., & Børsheim, E. (2013). Health effects of protein intake in healthy adults: a systematic literature review. Food & Nutrition Research, 57(1), 21245. https://doi.org/10.3402/fnr.v57i0.21245
Mayo Clinic. (2025). Dietary fiber: Essential for a healthy diet. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fiber/art-20043983
Suzuki, R., Rylander‐Rudqvist, T., Ye, W., Saji, S., Adlercreutz, H., & Wolk, A. (2007). Dietary fiber intake and risk of postmenopausal breast cancer defined by estrogen and progesterone receptor status—A prospective cohort study among Swedish women. International Journal of Cancer, 122(2), 403–412. https://doi.org/10.1002/ijc.23060
Tassinari, V., Smeriglio, A., Stillittano, V., Trombetta, D., Zilli, R., Tassinari, R., Maranghi, F., Frank, G., Marcoccia, D., & Di Renzo, L. (2023). Endometriosis treatment: Role of Natural Polyphenols as Anti-Inflammatory Agents. Nutrients, 15(13), 2967. https://doi.org/10.3390/nu15132967
Zeng, H. (2014). Mechanisms linking dietary fiber, gut microbiota and colon cancer prevention. World Journal of Gastrointestinal Oncology, 6(2), 41. https://doi.org/10.4251/wjgo.v6.i2.41
Zengul, A. G., Demark-Wahnefried, W., Barnes, S., Morrow, C. D., Bertrand, B., Berryhill, T. F., & Frugé, A. D. (2020). Associations between Dietary Fiber, the Fecal Microbiota and Estrogen Metabolism in Postmenopausal Women with Breast Cancer. Nutrition and Cancer, 73(7), 1108–1117. https://doi.org/10.1080/01635581.2020.1784444
Zheng, Y., Guo, Y., Song, C., Liu, G., Chen, S., Guo, X., & Lin, L. (2024). A cross-sectional study on the relationship between dietary fiber and endometriosis risk based on NHANES 1999–2006. Scientific Reports, 14(1), 28502. https://doi.org/10.1038/s41598-024-79746-9
