In the eighties, data started to emerge that propelled soy out of the province of the vegetarian-restaurant tofu burger and into the mainstream of nutrients considered essential for women's health. Epidemiologists began analyzing what factors might account for the fact that women in Asia have a lower incidence of heart disease and breast cancer than women in the United States, as well as less discomfort from symptoms of menopause. Soy seemed a likely explanation, because Asians eat so much of it and because it contains large amounts of phytoestrogens, compounds similar to the estrogen produced in the human body, only far weaker. Researchers speculated that these particular phytoestrogens, called isoflavones, might bind with estrogen receptors in the body, taking the place of some of the body's more powerful and potentially troublesome estrogen, thus decreasing overall estrogen levels. This decrease could help prevent cancerous tumors promoted by estrogen, especially in the breasts and ovaries. Epidemiological studies have borne this out, showing a lower incidence of breast cancer in women who consume at least one serving of tofu each week.

As research into soy's effects has accelerated, other benefits have turned up. Recent studies with laboratory rats have shown that a diet enhanced with soy increases bone formation, which might help prevent osteoporosis in older women. Isoflavones may also counteract reproductive cancers in women and reduce the incidence of prostate cancer in men. And the evidence for soy's ability to reduce susceptibility to heart disease may be the strongest indication of its medical benefits. Studies in the mid-nineties showed that consuming one-half cup of tofu per day can reduce total blood cholesterol, particularly the "bad" LDL cholesterol. Eating a whole cup heightens that effect (How Much Soy Should You Eat?). By late 1999 the FDA had authorized a health claim for food packaging stating that soy can help reduce the risk of coronary disease.

Return to Weighing the Health Benefits of Soy.