Does Soy Have a DARK SIDE?

Natural Health, March, 1999 by Sally Eauclaire Osborne

Second, a few researchers question if isoflavones could interfere with the hormonal and sexual development of children. Cliff Irvine, D.Sc., a reproductive endocrinologist at Lincoln University in Canterbury, New Zealand, studied the isoflavone levels in soy infant foods and found that the daily recommended intake of soy formula provides 3 mg of isoflavones per kilogram of body weight--a level he says is more than four times the level found to change reproductive hormones in women. His findings were published in Proceedings of the Society for Experimental Biology and Medicine in March 1998.

The findings of Irvine and other researchers led some New Zealand residents to lobby for a ban on the sale of soy infant formula except by prescription. The New Zealand government recently decided not to ban the formulas but rather to accelerate studies of possible adverse effects.

In America, the infant formula concern has received much less publicity, but Daniel M. Sheehan, Ph.D., a researcher at the FDA's National Center for Toxicological Research in Jefferson, Ark., expresses caution. "Infants fed soy-based formulas are part of a large, uncontrolled, and basically unmonitored human infant experiment, with uncertain risks and benefits," he says.

"There does exist a theoretical basis for raising concerns," Messina says in response to the formula charges. But, he adds, soy formula has been used in the United States for at least 30 years, without any apparent harm to infants. "To my knowledge there are no letters or case studies published in scientific journals citing problems in soy-fed infants that might be attributed to estrogenic effects. Furthermore, many short-term studies that have evaluated infants and children fed soy infant formula have concluded that soy formula promotes normal growth and development."

RELATED ARTICLE: SOY GLOSSARY

ISOFLAVONE a plant-based estrogen (also called phytoestrogen) that interrupts the function of hormonal estrogen. Two well-known isoflavones are daidzein and genistein.

MISO a condiment (similar in texture to peanut butter) made with soybeans, rice or barley, and salt, and fermented with microorganisms for one to three years. "Quick" miso is pasteurized and aged for only a few days and has a less complex taste.

NATTO cooked whole soybeans fermented with microorganisms. With its strong flavor, some call natto the Asian answer to blue cheese.

SHOYU traditional Asian soy sauce made from the liquid pressed from miso paste. Most soy sauce sold in the United States is unfermented and made from defatted soybean meal (mashed soybeans that have had the fat removed from them).

SOYMILK unfermented liquid made from soaked, ground, and cooked whole soybeans and water (also available as low-fat soymilk, which may contain soy protein isolate).

SOY PROTEIN ISOLATE an unfermented, highly refined soy protein used to make soy burgers, soy shakes, baked goods, and other foods.

TAMARI another name for traditional soy sauce (or shoyu).

TEMPEH cooked and fermented whole soybean cake. Can be eaten whole or crumbled into dishes.