Soy and isoflavonesSoybeans are the richest dietary source of isoflavones. Isoflavones belong to the group of phytochemicals and are being studied intensively because they extent physiological effects which may help reduce the risk for certain diseases. Epidemiological studies have indicated that populations which regularly consume soyfoods have lower incidences of breast, colon and prostate cancers. The incidence is particularly low for hormone-dependent cancers. In Asian countries, where the prevalence of disorders such as breast cancer and invasive prostate cancer is relatively low, people consume soy foods in amounts that provide on average 50-100 mg of soy isoflavones a day.
Studies show that isoflavones account for approximately three-fourths of soy's protection, while its protein is responsible for about one-fourth.
The best way to consume isoflavones is in food form, so that you can benefit from all of soy's nutrients and beneficial compounds. If you decide to take supplements, choose products that supply a mixture of isoflavones including genistein and daidzein. Try to ingest a total of 100 mg isoflavones a day from supplements, foods, or a combination of the two.
Isoflavones are fairly stable, so under normal home or institutional cooking methods isoflavones are not destroyed.
Another important plant source of isoflavones is red clover.