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Frequently Asked Soyfood Questions

 

Soy/Health

5. I just saw the 20/20 television program on soyfoods. Now, I'm wondering if soy is good for me to eat?

The Food & Drug Administration's (FDA's) approval of a health claim for soy protein's ability to lower cholesterol and help prevent coronary heart disease has generated much discussion (and some debate) about the efficacy of soy. While much of the research that has been cited points to the disease-fighting attributes of soy, a few individual studies that appear to raise questions about soy have recently received attention. One of the underlying concerns from these studies is that, because soy contains estrogen-like compounds, consuming soy may lead to hormone-related problems. However, in a recent study conducted at the University of Toronto, researchers concluded that soy is safe and does not contribute to hormone problems. Following are some facts that may help provide clarification and eliminate some of the confusion.

THE FDA ENDORSES SOY AS A HEALTHY ADDITION TO THE DIET

In November 1998, the FDA proposed a rule allowing a health claim that links the consumption of soy protein to a reduced risk of coronary heart disease. The public comment period that followed the proposed rule generated a myriad of comments from diverse groups. More than 100 comments were submitted by scientists, health organizations, companies and the general public, and fewer than 10 opposed the claim. After reviewing more than 40 scientific studies and all of the comments that were submitted, the FDA decided there was enough evidence to approve the soy protein health claim on October 26, 1999. The claim allows soyfoods that meet the FDA's criteria to carry a label stating that "25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease."

SOY REDUCES CANCER RISK

A number of studies suggest that soy isoflavones, specifically genistein and daidzein, may help reduce cancer risk. Researchers have proposed that soy has various mechanisms that inhibit the development and growth of cancerous tumors. One study involving 12,395 California Seventh-day Adventist men indicated that frequent consumption (more than once a day) of soymilk was associated with a 70 percent reduction in the risk of prostate cancer. Research on soy and the prevention of colon cancer has also produced encouraging results.

Some studies have raised concerns about the effect of soy isoflavones on estrogen-positive breast cancer. While these studies indicate a need for further research, there is strong evidence to suggest that soy is also beneficial in preventing breast cancer. The one study that is most often cited to illustrate possible adverse effects is a two-week study by McMichael-Phillips et al who found that soy isoflavones stimulated cell proliferation in breast cells taken from biopsies of premenopausal women with benign and malignant breast disease. In a recent follow-up analysis that included all subjects in the McMichael-Phillips study, Hargreaves et al found absolutely no effects on cell proliferation. While the research seems to be producing mixed results, there is reason to believe that studies currently underway will show that soy is safe for women in any situation.  

THE FACTS ABOUT SOY AND COGNITIVE FUNCTION

Recently, Dr. Lon White, a researcher from Hawaii, published results of a study linking mid-life tofu consumption to a decline in cognitive function among a sample of Japanese-American men. Although Dr. White's findings merit further research, they should be explored in the proper context. In the face of all the research that demonstrates the health-promoting properties of soy, it would be inappropriate to alter eating habits on the basis of one study, especially given that other research on soy and cognitive function does not support Dr. White's findings. 

Additionally, epidemiological studies like Dr. White's do not show cause and effect. While he tried to control for confounding variables, it is impossible to eliminate all of the genetic and lifestyle factors that could influence diminished cognitive function. It is impossible to conclude from these findings that there is a clear connection between tofu consumption and decreased cognitive function, and epidemiological findings are often refuted by clinical evidence. A classic example is a body of epidemiological studies suggesting that calcium intake may actually increase the risk of osteoporosis. After many human clinical trials, it has become widely accepted that calcium actually helps prevent osteoporosis.

INFANT FORMULA AS A SAFE AND NUTRITIOUS ALTERNATIVE

For more information on soy and infant formula go to the American Academy of Pediatric's web site.