Soy Isoflavones

About Soy Isoflavones

Isoflavones are a class of flavonoids found mainly in soybeans and other legumes, with genistein, daidzein and glycitein being the principal forms in soy. Because their structure resembles estradiol, they can bind estrogen receptors, with a preference for estrogen receptor beta, and are therefore classed as phytoestrogens. Gut bacteria in some people convert daidzein into equol, a more active metabolite, and the ability to produce equol varies between individuals and populations. Isoflavones have been studied for menopausal hot flashes, bone density, cardiovascular health and breast and prostate cancer, with mixed results. Concern that soy isoflavones might promote hormone sensitive cancers has not been supported by large observational studies of soy food intake. The US FDA authorized a heart health claim for soy protein in 1999 and later proposed revoking it, citing inconsistent evidence. Isoflavone content varies widely between soy foods and is affected by processing.