A recent study has demonstrated that isoflavones have potent antioxidant properties, comparable to that of vitamin E. The anti-oxidant powers of isoflavones can reduce the long-term risk of cancer by preventing free radical damage to DNA. Genistein is the most potent antioxidant among the soy isoflavones, followed by daidzein.

Research in several areas of healthcare has shown that consumption of isoflavones may play a role in lowering risk for disease. Isoflavones can fight disease on several fronts. The following potential health benefits are attributed to isoflavones.

In a vitro test it is seen that soy isoflavone genistein induces apoptosis and inhibits growth of both androgen-sensitive and androgen-independent prostate cancer cells. The aim of this study was to determine the clinical effects of soy isoflavones on prostate cancer cells. Tests were conducted on 41 patients with prostate cancer who had rising serum prostate-specific antigen (PSA) levels. There was a decrease in the rate of the rise of serum PSA. The research was done successfully and these data suggest that soy isoflavones may benefit some patients with prostate cancer.

Laboratory tests on rats have shown that soy isoflavones inhibit breast cancer. The associations between consumption of foods rich in isoflavones and breast cancer risk have been inconsistent in epidemiologic studies. The purpose of this study was to determine the relationship between isoflavones consumption and breast cancer risk among women on Cancer and Cardiovascular Diseases. A questionnaire was completed in 1990 by 21 852 female residents. The questionnaire included items about the frequency of soy consumption. After 9 years 179 women were diagnosed with breast cancer. The correlation was calculated between the development of breast cancer and the consumption of miso soup, soyfoods and calculated isoflavones. The consumption of miso soup and isoflavones, but not of soyfoods, was inversely associated with the development of breast cancer. It can be concluded that frequent miso soup and isoflavone consumption was associated with a reduced risk of breast cancer.