An excellent example is soy isoflavones. Research has shown that soybeans contain various anticancer phytochemicals. Dietary soybean consumption is believed to contribute to the low rate of breast cancer in Japanese women and prostate cancer in Japanese men. Also, studies show that Chinese who regularly consume soybeans have only 50 percent the incidence of colon, stomach, rectum, breast, and lung cancers as those who rarely consume soy foods. A review of 861 articles related to soy products and diets with high phytoestrogen content, concluded that phytoestrogens are among the dietary factors that protect against cancer and heart disease in vegetarians.
Soy contains two important isoflavones known as genistein and diadzein.
In the body, these substances are converted to phytoestrogens that affect hormone metabolism and estrogen activity in a protective manner. Interestingly, it appears that if the estrogen levels are too high the isoflavones have a blocking effect on the uptake of estrogen by cells-thus minimizing growth of estrogen dependent tumors. Women who consume a traditional Japanese diet excrete 1,000 times more genistein than those from societies with high breast cancer rates. Another class of therapeutic phytonutrients is flavonoids-many of them which contribute to the spectacular color of plants. Thousands have been identified.