- The Washington Times - Sunday, March 11, 2001

Walk down the aisles of any well-stocked grocery store, and you'll see virtual soy feast for the tasting soy milk, tofu, tempeh, Gardenburgers. You'll find soy cheese, soy hot dogs, soy yogurt.

Many of those products have become available in mainstream grocery stores within the past 17 months, ever since the U.S. Food and Drug Administration gave manufacturers of soy foods permission to tout soy's known health benefits on their labels.

In October 1999, manufacturers were given approval by the FDA to remind consumers that 25 grams of soy protein a day may reduce the risk of heart disease by lowering cholesterol levels.

Other health claims have received media attention but no formal FDA recommendation. There have been studies saying soy can have an effect on everything from managing menopause symptoms to preventing osteoporosis and certain cancers.

On those claims, the jury is still out, says Mark Messina, a soy researcher and professor of nutrition at Loma Linda University in California.

"It is true that soy protein will lower cholesterol levels," Mr. Messina says. "The effect is modest, but in some people, it is pronounced. That is why the FDA is allowing that health claim. The way to lower cholesterol is to not eat saturated fat, and there are a million things you can do about that, and soy can be a part of it."

To benefit from soy's effect on cholesterol, a person needs to have a cholesterol level of 240 or lower, Mr. Messina says. The FDA based its approval on evidence from dozens of studies showing that about 25 grams daily two to three servings of soy can lower cholesterol levels by about 5 percent.

Beyond cholesterol

It has been nearly two decades since American scientists began studying why Asian women had lower rates of breast cancer than American women. It isn't merely that Asian women eat a plant-based diet rich in soy products such as tofu.

Most Asian women grew up eating at least one serving of soy (about 2 to 3 ounces of tofu) daily, leading scientists to believe that soy consumption early in life can have a big payoff later, Mr. Messina says.

"It is very intriguing, " he says. "When dealing with breast cancer, it is very difficult to find post-menopausal lifestyle factors that have an effect. The situation is greatly influenced by early life effects and genetics. The lower rates in Japan may not be because they eat tofu as adults, but because they ate it as girls."

Soy's effect on breast cancer has to do with isoflavones, the naturally occurring plant estrogens found in soy products, says Barry Goldin, a professor of family medicine and community health at Tufts University.

Breast cells contain estrogen receptors, which enable them to recognize estrogen and absorb it into breast tissue. Because many breast cancers are exacerbated by estrogen, the goal is to keep estrogen out of breast tissues. Because isoflavones are weak estrogens containing between 1/100th and 1/1,000th of the potency of human estrogen breast receptors will allow them in instead, thereby blocking the more harmful effects of human estrogen, Mr. Goldin says.

"Soy is the only plant product we eat that has isoflavones, " he says.

There has been some emerging evidence, however, that the weak estrogens could act in conjunction with human estrogen, thereby increasing a woman's chances of breast cancer rather than preventing it.

It is a complicated equation, based on where a woman is in her life cycle and how much soy she is consuming, Mr. Goldin says.

There has been speculation that phytoestrogens can help counteract menopause symptoms, such as hot flashes, that occur because of a drop in hormone levels. This theory still is being investigated, he says.

"The issue is, if you are consuming 50 to 100 milligrams (about 6 to 8 ounces of tofu) daily, you can achieve blood levels high in estrogen," Mr. Goldin says. "Whether that is beneficial or harmful de-pends on your menopausal status. If you are pre-menopausal, soy may block estrogenic effects. if you are post-menopausal, then soy may act estrogenically."

Because the long-term effects of large quantities of soy are not known particularly for post-menopausal women Mr. Goldin recommends consuming no more than a few servings of tofu daily.

"Moderation in dosage is important," he says. "There are people out there who can get radical about consuming soy."

Mr. Goldin also cautions people against taking isoflavone supplements, which may expose them to very high levels of isoflavones without the benefits of the soy protein found in foods.

Melanie Polk, a registered dietitian and a spokeswoman for the American Institute for Cancer Research, agrees.

"There seems to be a feeling that if a little is good, then more is better," she says. "I have heard of some women eating soy cereal with soy milk, followed by soy cheese and soy nuts, all in one day. The bottom line is it does not seem to be a problem for people to include a serving or two of soy in the course of a day. But for women who have had or are at risk of having estrogen-positive breast cancer, I would not push huge amounts of soy."

In some consumers, soy can cause allergic reactions, such as hives, rash, difficulty breathing and upset stomach, says Nicole Cheeks, a spokeswoman for the Food Allergy Network, a nonprofit group that educates the public about food allergies.

Soy: The key to aging well?

The hormonal effects of soy isoflavones have led to more than 600 scientific papers filed on the subject last year, Mr. Messina says. The more research scientists do, the more complicated the picture becomes.

"You have to look at the totality of the argument," he says. "Probably out of everything, I am most excited by the findings about prostate cancer. The preliminary findings look encouraging."

Scientists are studying the lower prostate cancer rates among men in Japan, as well as the effect of soy on men who have had their prostates removed.

Several short-term studies also are testing the effects of isoflavones on osteoporosis. In a 1999 study of 50 post-menopausal women who consumed three glasses of soy milk (about 60 milligrams of isoflavones) daily for 12 weeks, there was an increase in the levels of bone-building cells.

"When women tend to lose bone, you can detect it biochemically," says soy researcher Kenneth Setchell, a professor of pediatrics at Children's Hospital of Cincinnati. "In this study, we observed a significant reduction in the amount of biochemical markers, suggesting reduced loss of bone cells. This was confirmed in two additional studies. It seems isoflavones in soy stack up well in improving bone density, but there needs to be more long-term studies."

Says Mr. Messina: "The preliminary data on bone health looks encouraging. There is speculation that weak estrogens have a favorable effect. But we do need longer studies."

Eventually, researchers might be able to confirm more health claims. For now, however, they recommend taking all the findings except for the FDA-approved cholesterol-lowering label as preliminary. Within reason, soy can be a low-fat, high-protein part of a diet, Mr. Messina says.

"I think it is one heck of a product," he says.


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