genistein is present at high levels in soy products.
Genistein is structurally similar to 17beta-estradiol
(E2), and genistein has been suggested to be act as
E2 or an antagonist against E2. Genistein suppresses
antigen-specific immune response in vivo and lymphocyte
proliferation response in vitro. However, genistein
enhances the cytotoxic response mediated by NK and cytotoxic
T cells and the cytokine production from T cells...isoflavones
play a beneficial role in obesity, cancer, osteoporosis,
and cardiovascular disease." http://www.ncbi.nlm.nih.gov/pubmed/18797128
"Genistein is one of several known isoflavones.
Isoflavones, such as genistein and daidzein, are found
in a number of plants including lupin, fava beans, soybeans,
kudzu, and psoralea being the primary food source,
also in the medicinal plant, Flemingia vestita and
coffee. Besides functioning as antioxidant and anthelmintic,
many isoflavones have been shown to interact with animal
and human estrogen receptors, causing effects in the
body similar to those caused by the hormone estrogen.
Isoflavones also produce non-hormonal effects."