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.
Is it good for the heart? Eating soy protein can help lower your consumption of heart-damaging saturated and trans fats. Soy protein, unlike other proteins, may lower LDL (bad) cholesterol slightly, although the large amount of it required to produce this effect makes it impractical. But there's no scientific evidence that the phytoestrogens in soy are heart-protective. Soy isoflavones do not lower cholesterol, nor do they have any significant effect on blood pressure.