If hormone replacement therapy has gotten a drubbing of late, so too has a much-celebrated food that many women eat to help ease the symptoms of menopause and to protect against heart disease and osteoporosis: the soybean.
Some scientists are increasingly wary about Americans going hog-wild for soy, soy protein and the estrogen-like chemicals (isoflavones) that soy protein contains.
A soon-to-be-published study linking tofu to a faster decline in mental abilities is particularly unwelcome news for any woman who sees eating soy as risk-free, either as well as or in addition to conventional hormone replacement therapy. How seriously should she view this new twist to the soy story? Should she toss out her tofu? Swear off soy burgers?
Most soy scientists simply preach moderation.
"The majority of evidence indicates that soy is a safe food that's eaten by two-thirds of the world's population," says Dr. David Heber, director of UCLA's Center for Human Nutrition, adding that it does appear to have health benefits. But Heber and others warn against eating soy to the exclusion of other foods: A varied diet is important to good health. And they caution against consuming very large amounts of soy protein or popping isoflavone pills available in stores.
"There's a tendency in our culture to think if a little is good, then a lot's better," says Mary Anthony, a soy researcher at Wake Forest University School of Medicine in Winston-Salem, N.C. "But I personally am very concerned about isoflavone pills and soy protein supplemented with extra isoflavones."
Isoflavones, after all, seem to act like hormones or drugs in our body--even if for regulatory purposes they are classified as nutritional supplements.
Some of the druglike effects of soy protein or the isoflavones they contain could be good for us. Several dozen clinical studies have reported, for instance, that eating an average of 25 grams of soy protein daily for several weeks to months lowers blood levels of "bad" (or LDL) cholesterol and may help elevate "good" (or HDL) cholesterol levels--in other words, may help protect against heart disease.
Based on such studies, the U.S. Food and Drug Administration now allows foods with at least 6.25 grams of soy protein per serving to be labeled with claims stating that they could help reduce the risk for heart disease.
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Soy protein (probably because of its isoflavones) might also help keep bones strong, as well as ward off prostate or breast cancer.
