Soy,
a staple food in many Asian countries, contains valuable constituents,
including protein, isoflavones, saponins, and phytosterols. Soy protein
provides essential amino acids. When eaten with rice, soy provides protein
comparable to that found in animal products. Soy is low in fat and cholesterol-free.
The isoflavones in soy, primarily genistein and daidzein, have been well researched by scientists for their antioxidant and phytoestrogenic properties. Saponins enhance immune function and bind to cholesterol to limit its absorption in the intestine. Phytosterols and other components of soy have been reported to lower cholesterol levels.
Breast Cancer: A major study in Singapore revealed that women who eat soya foods are at lower risk of developing breast cancer than those who don't. Asian women, who typically eat a soya-based diet, have much lower levels of breast cancer than Western women. Test tube studies and those involving laboratory animals have shown that "compounds in soya can inhibit the growth of breast cancer cells." The studies presented at a Medical Conference in Brussels in September 1996 indicate that the isoflavones in soya may be the reason for these lower cancer rates.
Cholesterol: Scores of studies from around the world attest to soya's cholesterol-lowering properties, especially for people with high cholesterol. soya strongly inhibits LDL oxidation and neutralizes free radicals in blood platelets.
Colon Cancer: A recent US study showed that American soya eaters who make soybeans and tofu a regular part of their diet had significantly lower rates of colon cancer than those who didn't eat soya.
Osteoporosis: Hip fractures owing to osteoporosis are a major problem among elderly women in the United States. Japanese women have half the rate of hip fractures as US women. Preliminary studies suggest that soya may help retain bone mass. Also, it appears that soya protein doesn't increase the excretion of calcium in the urine as is the case with high protein diets.
Hot Flashes: Half of all menopausal women in the United States complain of hot flashes, a problem that is so rare in Japan that there's not even a word for it. Some researchers believe that special compounds in soya called phytoestrogens may help Japanese women stay cooler.
Immunity: Studies show that soybean peptides can boost the immune system, helping the body fight disease.
Kidney Disease: soya protein is easier on the kidneys, the main filtering organ of the body, than is animal protein and may slow down or prevent kidney damage in people with impaired kidney function.
Lung Cancer: Several studies have linked soya consumption to lower rates of lung cancer.
Prostate Cancer: A major study of Japanese men in Hawaii found a direct correlation between consumption of tofu and lower rates of prostate cancer. Studies of soya compounds have shown that they can inhibit the growth of prostate cancer cells in laboratory cultures. Contrary to some beliefs, the phytoestrogens in soya are not detrimental to anabolic hormones or muscle.