Soy, disease prevention, and prostate cancer.

Population-based studies from around the world support the theory that soy products and their constituents, primarily the isoflavones or phytoestrogens, are partly responsible for the lower rates of certain chronic diseases in different areas of the world. Cardiovascular disease and hormonally induced cancers are just a few of the conditions lower in Asian countries that consume large quantities of soy per average person. Genistein, one of soy's individual phytoestrogens, has been found to inhibit numerous breast and prostate cancer cell lines. A limited amount of clinical evidence also points to a beneficial role of soy in reducing hormonal levels and exhibiting weak estrogen and antiestrogen-like qualities. Other phytoestrogens found in nature, such as lignans, may also have a future role in cancer. Collectively, these phytoestrogens, like genistein, have enough evidence to warrant their use in a number of clinical trials as a potential chemopreventive agent or adjunct to prostate cancer treatment.