With Americans on track to consume $8.5 billion worth of soyfoods by 2007, and up to 20 percent of formula-fed American infants being given soy-based formula, the health benefits and risks of soyfoods have become a topic of hot debate. An expert panel convened by the Center for the Evaluation of Risks to Human Reproduction (a division of the U.S. Department of Health and Human Services) recently evaluated the reproductive and developmental effects of soy formula and genistein, a naturally occurring estrogen in soybeans.
Genistein is found in soyfoods like tofu and soy milk, and in dietary supplements. Some researchers believe genistein may contribute to lower rates of breast, ovarian, and prostate cancer in countries where people eat plentiful soyfoods. However, genistein has also gotten some negative attention for mimicking estrogen in the body, leading some to speculate on its role in early puberty in girls.
The good news: The 14 independent experts on the panel came down squarely in favor of genistein's safety. The scientists estimated that to approach a potentially harmful level, an adult would need to consume 75 times as much genistein as the average Japanese, the most soy-centric people on the planet.
The mixed news: The experts were more divided on the reproductive and developmental safety of soy formula for babies, concluding that there was insufficient evidence on the matter. Most of the experts felt there was only "negligible" concern about the safety of soy formula, but at least one scientist said a higher level of concern was warranted.