Phytoestrogens are plant hormones chemically similar to the estrogens found in humans. An example of a phytoestrogen is soy. Phytoestrogens treat a variety of health conditions and affect breast tissue. There are claims that phytoestrogens may enhance breast development, but a greater volume of research has investigated how phytoestrogens effect breast cancer. Epidemiological studies primarily show phytoestrogens to have a protective effect against breast cancer.
Classes of phytoestrogens include isoflavones, lignans and coumestans. Isoflavones, specifically genistein and daidzein, have the highest estrogen properties and are found in legumes such as:
Coumestans are found in sprouting plants. Phytoestrogens, primarily isoflavones, are also found in processed and packaged foods and in infant soy formula. Often they are used as a preservative.
- Classes of phytoestrogens include isoflavones, lignans and coumestans.
- Phytoestrogens, primarily isoflavones, are also found in processed and packaged foods and in infant soy formula.
Effect on Breast Tissue
Is Soy Safe When Pregnant?
Because phytoestrogens mimic estrogen, interest exists on how they effect the body's hormones. How phytoestrogens effect breast tissue is an area of much speculation, specifically in areas such as breast cancer and breast enlargement. Phytoestrogens have the biggest impact on breast tissue when exposure occurs prior to puberty. There is an association between high soy intake early in life and increased breast density.
- Because phytoestrogens mimic estrogen, interest exists on how they effect the body's hormones.
- How phytoestrogens effect breast tissue is an area of much speculation, specifically in areas such as breast cancer and breast enlargement.
Effects of Phytoestrogens on Breast Development
Claims exist that phytoestrogens may increase breast size. A March 2010 study published in the “BOR Papers in Press” stated that genistein exposure in infants fed soy formula induces estrogenic changes in both reproductive and non-reproductive organs. Another study in the “Journal of Pediatric Gastroenterology and Nutrition” in February 2008 showed that infants fed soy formula had an increase in breast development in the second year of life, suggesting that phytoestrogens contribute to the retention of infantile breast tissue 2. These studies reflect infantile exposure to soy in extremely high amounts, not consumers seeking to increase breast size. Many cosmetic and supplement companies advertise their products to increase breast size due to phytoestrogens, but use caution before you purchase these products.
- Claims exist that phytoestrogens may increase breast size.
- Another study in the “Journal of Pediatric Gastroenterology and Nutrition” in February 2008 showed that infants fed soy formula had an increase in breast development in the second year of life, suggesting that phytoestrogens contribute to the retention of infantile breast tissue 2.
Phytoestrogen Effects on Breast Cancer
Are There Foods That Work Like Female Hormones?
Overall, phytoestrogens have a protective effect against breast cancer, though research has shown that in some cases they may induce tumor development. A study in the "Journal of Clinical Oncology" in February 2007 showed phytoestrogens to behave like estrogen when natural estrogen levels are low and unlike estrogen when levels are high 3. Premenopause, phytoestrogens protect against breast cancer when estrogen levels are high, but promote the growth of cancer cells post-menopause when estrogen levels are low. This study also showed that higher levels of the isoflavone genistein slows the development of tumor cells, protecting against breast cancer.
- Overall, phytoestrogens have a protective effect against breast cancer, though research has shown that in some cases they may induce tumor development.
Is Soy Safe When Pregnant?
Are There Foods That Work Like Female Hormones?
Ways to Naturally Stimulate Breast Growth
What Are the Dangers of Soy Isoflavones?
What Are the Dangers of Parabens in Skin Care?
Benefits of Soy Protein for Breast Growth
Which Foods Are High in Natural Estrogen?
What Are the Side Effects of Parabens?
Is it Possible to Take Vitex With Birth Control?
Foods That Act Like Estrogen
- “BOR Papers in Press”; Acute and Chronic Effects of Oral Genistein Administration in Neonatal Mice; Melissa A. Cimafranca, et al.; March 2010
- “Journal of Pediatric Gastroenterology and Nutrition”; Breast Development in the First 2 Years of Life; Amnon Zung, et al.; February 2008.
- “Journal of Clinical Oncology”; Plasma Phytoestrogens and Subsequent Breast Cancer Risk; Martijn Verheus, et al.; February 2007
- Zhang GQ, Chen JL, Liu Q, et al. Soy Intake Is Associated With Lower Endometrial Cancer Risk: A Systematic Review and Meta-Analysis of Observational Studies. Medicine (Baltimore). 2015 Dec;94(50):e2281. doi:10.1097/MD.0000000000002281.
- Tse G, Eslick D. Soy and isoflavone consumption and risk of gastrointestinal cancer: a systematic review and meta-analysis. Eur J Nutr. 2016 Feb;55(1):63-73. doi: 10.1007/s00394-014-0824-7
- Anderson JW, Bush HM. Soy protein effects on serum lipoproteins: a quality assessment and meta-analysis of randomized, controlled studies. Journal of the American College of Nutrition 2011 Apr;30(2):79-91.
- Greendale GA, Tseng CH, Han W, et al. Dietary Isoflavones and Bone Mineral Density during Mid-Life and the Menopause Transition: Cross-Sectional and Longitudinal Results from the SWAN Phytoestrogen Study. Menopause. 2015 Mar;22(3):279-88. doi:10.1097/GME.0000000000000305
- Rietjens IMCM, Louisse J, Beekmann K. The potential health effects of dietary phytoestrogens. Bri J Pharmacol. 2017 Jun;174(11):1263-80. doi:10.1111/bph.13622
- Terzic M, Micic J, Dotlic J, et al. Impact of Phytoestrogens on Serum Lipids in Postmenopausal Women. Geburtshilfe Frauenheilkd. 2012 Jun;72(6):527-31. doi:10.1055/s-0031-1298624
- Wei P, Liu M, Chen Y, Chen DC. Systematic review of soy isoflavone supplements on osteoporosis in women. Asian Pac J Trop Med. 2012 Mar;5(3):243-8. doi:10.1016/S1995-7645(12)60033-9
- Yu Y, Jing X, Li H, et al. Soy isoflavone consumption and colorectal cancer risk: a systematic review and meta-analysis. Sci Rep. 2016;6:25939. doi:10.1038/srep25939
- Ziaei S, Halaby R. Dietary Isoflavones and Breast Cancer Risk. Medicines (Basel). 2017 Jun;4(2):18. doi:10.3390/medicines4020018
- “Archives of Internal Medicine”; Review of the Evidence; M. Gina Glazier, et al.; May 2001
- “The Catholic University of Korea”; Breast Augmentation; Jin Wha Chung
- “Environmental Health Perspectives”; Pilot Studies of...; Judy Bernbaum, et al.; March 2008
- “Frontiers in Neuroendocrinology”; The Pros and Cons; Heather Patisaul, et al.; March 2010
- “The Journal of the American Medical Association”; Soy Food Intake; Xiao Ou Shu, et al.; 2009
- “Scientia Pharmeceutica”; Phytoestrogen Biological Actions; E Zhao, et al.; March 2011
- “Society for Endocrinology”; Phytoestrogens and Breast cancer; Suman Rice; December 2006
Elizabeth Langer has practiced acupuncture and chiropractic medicine since 2009. She graduated from New York Chiropractic College with her Doctor of Chiropractice degree in 2008 and her master's degree in acupuncture in 2009. Langer treats a variety of conditions and incorporates nutrition based on whole foods and Chinese medicine into her practice. She has been writing health-related articles since 2006.