The Dark Side of Soy
Supplements may do more harm than good

You see soy in everything from burgers to breakfast cereals. Studies show it can lower heart disease risk by reducing LDL, or bad, cholesterol--the Food & Drug Administration even said so in 1999. And many food companies claim it's helpful in treating hormonally linked problems, such as prostate cancer, osteoporosis, and hot flashes. If you believed all the hype, you'd be feasting on soy morning, noon, and night.

But wait. Eating too much soy may do you more harm than good. Research scientists and doctors say that soy and its chemical components may promote cancer, dementia, reproductive abnormalities, and thyroid disorders. ''You don't want to go overboard with soy,'' says Bonnie Liebman, who is director of nutrition at the Center for Science in the Public Interest in Washington, D.C.

You especially don't want to take a soy supplement, energy bar, or powder that contains isoflavones, a chemical in soybeans. Isoflavones are phytoestrogens, or plant substances that behave like weak forms of the hormone estrogen. Estrogen relaxes the capillaries and primes the liver to get rid of cholesterol, so likely it's the phytoestrogens in soy that help reduce your chance of developing heart disease.

WHOLE FOODS. But despite what makers of dietary supplements would have you believe, research has shown that isoflavones alone have little effect on cholesterol levels. ''It's probably the many different chemicals found in soy along with the fiber that work together synergistically to produce beneficial effects,'' says Claude Hughes, author of several studies on soy and director of the Center for Women's Health at Cedars-Sinai Medical Center in Los Angeles.

Worse, consuming isofla-vones at high levels ''has been shown to have long-term detrimental effects,'' says Dr. Kenneth Setchell, a leading soy researcher and professor of pediatrics at the University of Cincinnati College of Medicine. For example, farm animals given large quantities of isoflavone-rich feed have developed serious reproductive, thyroid, and liver problems. A study published in 1998 in the journal Cancer Research indicates isoflavones promote the growth of human breast-cancer cells implanted in rats. Plus, women drinking isoflavone-infused soy drinks have been shown to have an increased proliferation of breast cells. The more breast-cell growth, the greater the risk of tumors. Alice Lichtenstein, professor of nutrition at Tufts University in Boston, warns that isoflavones and other chemicals extracted from foods are essentially drugs, and you can easily ingest harmful amounts because of the vast quantities that can be packed into a tiny pill.

The best way to take advantage of soy's health benefits is to follow the example of the Japanese and stick with whole foods. As a population, the Japanese tend to be healthier and live longer than Americans, and they eat around 7 grams to 10 grams per day of whole soy foods, such as tofu, soy milk, and edamame, as well as the fermented versions, tempeh and miso (table). Unlike soy hot dogs, ice cream, chips, and cookies, which often are made out of soy protein isolate derived from the soybean through chemical extraction, whole soy foods ''are closer to what Mother Nature intended,'' says Gregory Burke, chair of the department of public health science at Wake Forest University School of Medicine in Winston-Salem, N.C. That way, none of the potentially beneficial components have been discarded during processing.

Even with whole soy foods, there are caveats. If you are pregnant, at risk of developing estrogen-sensitive tumors, such as breast and ovarian cancer, or have a family history of dementia, many researchers and physicians advise against eating too much soy in any form. But if you don't fall into one of the risk groups, just remember: Stick with natural forms of soy, and avoid things that come out of a laboratory.


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The Dark Side of Soy

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