Differentiating between
PLANT PHYTOESTROGENS
(ISOFLAVONES) AND ESTROGEN
WHAT IS ESTROGEN?
A hormone produced by both women and men
WHAT ARE PHYTOESTROGENS?
Naturally occurring compounds in plants that share some similarities with estrogen
WHAT ARE ISOFLAVONES?
A type of phytoestrogen that is found in many plants, but especially soybeans
WHY ARE ESTROGEN & ISOFLAVONES DIFFERENT?
Isoflavones bind to estrogen receptors in cells in a manner that differs from the way estrogen does
QUICK FACTS
1 Soyfoods do not contain human estrogen
2 Soybean isoflavones are not the same as human estrogen
3 Isoflavones may be protective against breast cancer1-6
4 Isoflavones have no effect on the uterus7
5 Isoflavones do not lower testosterone in men, and do not affect sperm or semen8-9
1Hargreaves DF, Potten CS, Harding C, et al. Two-week dietary soy supplementation has an estrogenic effect on normal premenopausal breast. J Clin Endocrinol Metab. 1999;84(11):4017-24. https://www.ncbi.nlm.nih.gov/pubmed/10566643.
2Sartippour MR, Rao JY, Apple S, et al. A pilot clinical study of short-term isoflavone supplements in breast cancer patients. Nutr Cancer. 2004;49(1):59-65. https://www.ncbi.nlm.nih.gov/pubmed/15456636.
3Palomares MR, Hopper L, Goldstein L, et al. Effect of soy isoflavones on breast proliferation in postmenopausal breast cancer survivors. Breast Cancer Res Treatment. 2004;88 (Suppl 1)4002 (Abstract).
4Cheng G, Wilczek B, Warner M, et al. Isoflavone treatment for acute menopausal symptoms. Menopause. 2007;14(3 Pt 1):468-73. https://www.ncbi.nlm.nih.gov/pubmed/17290160.
5Khan SA, Chatterton RT, Michel N, et al. Soy isoflavone supplementation for breast cancer risk reduction: A randomized phase II trial. Cancer Prev Res (Phila). 2012;5(2):309-19. https://www.ncbi.nlm.nih.gov/pubmed/22307566.
6Shike M, Doane AS, Russo L, et al. The effects of soy supplementation on gene expression in breast cancer: a randomized placebo-controlled study. J Natl Cancer Inst. 2014;106(9). https://www.ncbi.nlm.nih.gov/pubmed/25190728.
7Mareti E, Abatzi C, Vavilis D, et al. Effect of oral phytoestrogens on endometrial thickness and breast density of perimenopausal and postmenopausal women: A systematic review and meta-analysis. Maturitas. 2019;12481-8.
https://www.semanticscholar.org/paper/Effect-of-oral-phy-toestrogens-on-endometrial-and-of-Mareti-Abatzi/d562204ead8a485909e3a1e985700c88b8632e6f.
8 Beaton LK, McVeigh BL, Dillingham BL, et al. Soy protein isolates of varying isoflavone content do not adversely affect semen quality in healthy young men. Fertil Steril. 2010;94(5):1717-22. https://www.ncbi.nlm.nih.gov/pubmed/19819436.
9Mitchell JH, Cawood E, Kinniburgh D, et al. Effect of a phytoestrogen food supplement on reproductive health in normal males. Clin Sci (Lond). 2001;100(6):613-8. https://www.ncbi.nlm.nih.gov/pubmed/11352776.
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