The evidence that links soy-rich diet to cancer prevention is growing all the time. People who live in countries where soy products are regularly consumed are less likely to develop certain cancers. In Asia for example breast cancer mortality rates are much lower.
Women in the United States are 4 times more likely to die from breast cancer that women in Japan, because soy products are consumed less in the US. Soyfoods help protect against several types of cancer, including colon, lung, stomach, rectal and prostate cancer.
The main reason why this is so, could be that soyfoods are rich in compounds called phytochemicals. Isoflavones, which are a particular family of phytochemicals, may fight cancer in a wide variety of ways. Isoflavones are found in significant amounts only in soyfoods such as soy milk, tofu, tempeh and textured soy protein and of course soybeans.
One isoflavone, Genistein, has captured the most attention. Genistein is a chemical compound that is found only in soy in our daily foods. Dr. Lothar Schweigerer from Heidelberg University found out that genistein blocks an event called angiogenesis.
Angiogenesis is the growth of new blood vessels that feed malignant tumors. When the tumor grows larger than 1 mm., it must foster the growth of new blood vessels to support the tumor[ growth. Tumors only thrive when tiny networks of new blood vessels supply them with oxygen and nutrients.
When genistein is added to live cells of liver cancer in laboratory test tubes, they stop growing. More than 100 studies on a variety of cancer cells have demonstrated the effectiveness of genistein. Geinstein fights cancer in many other ways as well. Scientists believe that specific enzymes in the body convert normal cells to cancer cells. Genistein has been shown to inhibit these enzymes just as some cancer drugs.
Genistein may also work against cancers like breast and prostate cancer that depend on hormones to grow. Genistein interferes with these hormones, therefore inhibiting the development of cancer cells and tumors.