Soy: Not so miraculous?

Soy has gained quite a reputation as a health food. In 1999, the FDA approved food label claims of a link between soy protein and a reduced risk for heart disease. The next year, the American Heart Association announced it "prudent" to include soy protein in a diet low in saturated fat and cholesterol. The low incidence of breast cancer in soy-consuming countries has also fueled speculation that it might prevent cancer.

As an alternative to eating lots of red meat, soy is a good choice. But there's little evidence that it confers all the health benefits attributed to it. Attention has focused mainly on isoflavones, components of soy that sometimes act like the hormone estrogen and sometimes inhibit it.