Phytoestrogens, or isoflavones, are plant-based compounds that bear chemical similarities to the estrogen that your body makes. Both men and women produce estrogens, and cells possess receptors that respond to this hormone. Hence, phytoestrogens can exert estrogen-like effects in the bodies of both sexes. Duane Townsend, M.D., author of "A Maverick of Medicine Speaks to Women," reports that more than 300 plants contain phytoestrogens, but soy has received the most attention from scientists.
Soy Isoflavones
The primary isoflavones in soy are genistein and daidzein. These compounds have been the subjects of the most extensive research on phytoestrogens because of their putative health benefits, such as a possible reduction in the risk for breast cancer. Of the foods listed in the U.S. Department of Agriculture Database on the Isoflavone Content of Foods, raw soybeans, including edamame, are among the richest food sources of genistein and daidzein.
Estrogen Dominance
One of the most important properties of soy isoflavones, according to Townsend, is their ability to counteract the influences of estrogens produced in your body and alleviate a condition called "estrogen dominance." Phytoestrogens attach to the same cellular receptors as your own estrogens but they exert weaker effects. Once the receptors are occupied by phytoestrogens, more potent estrogens, including synthetic, prescription estrogens, cannot stimulate those same receptors. According to a 2009 review in the "American Journal of Clinical Nutrition," this property may account for the reduced risk of breast cancer found among women who regularly consume soy products.
Potential Benefits of Soy
In 2008 the U.S. Department of Agriculture cited some of soy's reputed health benefits in its database of isoflavone food sources. Soy isoflavones have been shown to reduce total and LDL cholesterol, lowering your risk for heart disease. Soy may improve skeletal strength in premenopausal women, and soy isoflavones may reduce a man's risk for prostate cancer. Although the data surrounding soy's effects on breast tissue are still hotly debated, a 2010 review in the "Journal of Nutrition" contends that there is no evidence that soy consumption exerts any relevant adverse health effects.
Considerations and Precautions
Soy foods are traditionally consumed in cultures where the risks for some chronic diseases, such as heart disease and breast cancer, are lower than they are in societies where soy is a less prominent part of the diet. Research shows that soy isoflavones may confer health benefits for specific organs, such as the heart, prostate and bones. Soy isoflavones are not approved for preventing or treating any condition, however, and their effects on breast tissue are still a matter of conjecture. If you are interested in trying soy estrogens, talk with your doctor.
References
- "A Maverick of Medicine Speaks to Women: A Primer on Phytoestrogens"; Duane Townsend, M.D.; 2003
- U.S. Department of Agriculture Database for the Isoflavone Content of Selected Foods
- "American Journal of Clinical Nutrition"; Perspectives on the Soy-Breast Cancer Relation; M. Messina, A.H. Wu; May 2009
- "Journal of Nutrition"; Insights Gained from 20 Years of Soy Research; M. Messina; December 2010
