Results of two studies, one conducted in animals and one in humans, considered together suggest that a diet high in soybeans and other legumes during pregnancy and breastfeeding may have a subtle but long-term impact in helping children develop normally. The studies were presented November 3 in Washington, D.C., at the Third International Symposium on the Role of Soy in Preventing and Treating Chronic Disease sponsored by the American Oil Chemists' Society.
Soybeans and other plants contain compounds called isoflavones or phytoestrogens, which have been found to produce a variety of mild hormonal actions in the human body. Recent studies confirm that these compounds may be helpful in treating and preventing a variety of conditions, including unpleasant symptoms of menopause.
"At the beginning of the life span, when tissues in our bodies are being organized in utero and in the first months of life, there is good reason to believe -- based on animal studies and some human observations -- that sex hormones are very important in getting things organized properly," said Dr. Claude Hughes, director of the Center for Women's Health at Cedars-Sinai Medical Center in Los Angeles and lead investigator on the studies presented.
Barbara Gollman, a registered dietician based in Dallas and spokesperson for the American Dietetic Association (www.eatright.org), acknowledged that the compounds in soy are beneficial in a number of ways: They may help to preserve bone health as women age, treat symptoms of menopause, fight against heart disease and lower cholesterol levels. However, Gollman stressed, "As people become more aware of the health benefits of [phytoestrogen found in] soybeans, they may tend to overdo it." Gollman added that scientists "really don't have information" about phytoestrogen when it is extracted from soy products and packaged in pill form.
Gollman suggested, instead, that pregnant and nursing women "eat a well-balanced diet, with plenty of protein, calcium and nutrients, and focus on known, healthy foods."
Leslie Bonci, a registered dietician and director of sports medicine nutrition at the University of Pittsburgh Medical Center, expressed similar concern that the study and others like it might lead to pregnant women overloading on soy: "Nobody knows what effect these compounds are going to have on the fetus. They could alter its normal development." Bonci stressed the need to choose soy foods, such as soy milk, tofu and soy nuts, which contain isoflavones, and warned against pill versions of soy.
Hughes said that his researchers are currently seeking a grant to track outcomes of human babies exposed to phytoestrogens. "There are many long-term health questions that come about when the little clocks in our heads are changed. There may be subtle things occurring and we don't know it. Or it could be that humans are much more resistant to these effects than are other animals, and this is not an issue. We will not know until we get the data."
Gollman suggested that the study's focus seemed to be more on the rats tested than on pregnant or nursing humans: "I think the significant thing here is that these folks are looking for funding for more studies because they want more money for further research."
