Soy Foods May Slow Development of Prostate Cancer

American men are almost five times as likely to die from prostate cancer as Japanese men. This prompts speculation that soyfoods such as tofu, commonly consumed in Japan, may reduce prostate cancer risk. Experimental evidence supports this, according to a presentation by Dr. Mark Messina, at the 40th Annual Meeting of the American College of Nutrition, held in Washington, DC, October 1999.

Seventh-Day Adventist men in California who consumed soymilk at least once per day had a 70% reduced risk of developing prostate cancer, according to a study at Loma Linda University. An earlier study found similar results for Japanese men living in Hawaii who ate tofu.

Soybeans are a unique source of phytochemicals, or chemicals found in plants, called isoflavones. People who consume soyfoods have high blood levels of isoflavones; levels in those who don't consume soyfoods are negligible.

Hundreds of laboratory studies have found that isoflavones directly inhibit the growth of different types of cancer cells. Recently, soybean isoflavones were found to markedly inhibit prostate tumors in mice implanted with prostate cancer cells. Other research indicates isoflavones are concentrated in prostate tissue, providing further support for the notion that soyfoods may reduce prostate cancer risk. 

Isoflavones appear to work against prostate cancer in at least two ways. First, they initiate a process called apoptosis, a sort of cancer cell suicide. Second, they inhibit angiogenesis, or the growth of new blood vessels, which is necessary for tumor survival. Without new blood vessels, tumors starve to death because they can't get the oxygen and nutrients needed for growth.

 In Japan, men are as likely to develop prostate tumors as in America, but they are far less likely to die from prostate cancer. This indicates that, in Japanese men, prostate tumors grow more slowly. Men in Japan die with prostate cancer rather than from prostate cancer.

In the USA, over 30,000 men are expected to die of prostate cancer in the next 12 months. The risk is higher for African American men. Anything that slows tumor growth or delays tumor development even slightly could significantly reduce death from prostate cancer.

Even moderate amounts of soyfoods - just one serving per day - may reduce prostate cancer risk. Soymilk can be used as a beverage, over cereal or in baking. Tofu can be used cubed or sliced in just aboout any sauce such as spahghetti sauce as well as in oriental stir-fry and steamed dishes. Tofu can also be sliced and used in sandwiches. Or blend it with fruit to make shakes and creamy desserts.