News Briefs

Panel of Scientists Evaluates Genistein and Soy Formula

A panel of scientists has concluded that unless exposure levels change, adults would be unlikely to consume sufficient daily levels of genistein to cause adverse reproductive and/or developmental effects. The Center for the Evaluation of Risks to Human Reproduction (CERHR) convened this expert panel on March 15–17, 2006, in Alexandria, VA, to evaluate genistein and soy formula.

CERHR, which was established by the National Institute of Environmental Health Sciences (NIEHS) as part of the National Toxicology Program (NTP) in 1998, selected genistein and soy formula for expert panel evaluation for several reasons. One is the availability of reproductive and developmental toxicity studies in laboratory animals and humans. The second is the availability of information on exposures in infants and women of reproductive age, and the last is public concern for effects on infant or child development.

Genistein is a phytoestrogen found in some legumes, especially soybeans. Genistein and genistin are found in many food products, especially soy-based foods such as tofu, soy milk, and soy infant formula, and in some over-the-counter dietary supplements. Soy formula is fed to infants as a supplement or replacement for human milk or cow milk.

The expert panel, composed of 14 independent scientists, reviewed and evaluated the available scientific data on genistein and soy formula in three primary areas: human exposure, reproductive toxicity, and developmental toxicity. In their deliberations, the panel considered the quality, quantity, and strength of the scientific evidence that exposure to genistein or soy formula might cause adverse effects on human reproduction and/or development of the fetus or infant. The panel also identified gaps in the available scientific data on the possible effects of genistein and soy formula and suggested areas where additional research is needed. All members of the panel served as individual experts and not as representatives of their employers or other organizations.

Here are some of the conclusions on genistein:

  • Even though there is a paucity of available human data on exposure to purified genistein, the panel expressed negligible concern for reproductive and developmental effects from exposure of adults in the general population. The most highly exposed human population reported is Japanese adults with ingestion of total genistein (free and complexed) of approximately 0.43 mg/kg body weight (bw)/day. However, adverse effects in rodent studies were not observed at levels below 35–44 mg/kg bw/day.
  • The panel expressed negligible concern for adverse effects in neonates and infants who may consume up to 0.01-0.08 mg/kg bw/day of genistein aglycone contained in soy formula. One member of the panel did not agree with this conclusion and felt that a higher level of concern was warranted. It is noteworthy that about 1% of total genistein in soy formula is present in its uncomplexed form.

The panel also concluded that there are insufficient human or experimental animal data available to permit a determination of the developmental or reproductive toxicity of soy infant formula.

The final expert panel reports on genistein and soy formula will be posted on the CERHR website (http://cerhr.niehs.nih.gov) and available in printed text from CERHR in May 2006. CERHR will solicit public comments on these reports through an announcement in the Federal Register. Following this comment period, CERHR will prepare two NTP/CERHR monographs, one on genistein and one on soy formula, that consist of an NTP brief, the expert panel report, and all public comments on that report. The monographs will be available to the public in PDF format on the CERHR website and in hardcopy by contacting CERHR and will be distributed to appropriate federal health and regulatory agencies.

Rural Older Adults Use CAM, but Focus on 'Home Remedies'

A survey of older adults in rural North Carolina shows that they widely use complementary medicine therapies, but tend to focus on folk or home remedies, such as taking a daily "tonic" of vinegar or using Epsom salts. The goal of the study, which is reported in the March issue of Journal of Gerontology: Social Sciences, was to learn more about what complementary and alternative medicine (CAM) therapies older adults are using and why.

The ELDER (Evaluating Long-term Diabetes Self-management among Elder Rural Adults) study assessed complementary medicine use among 701 rural adults older than age 65 with diabetes. Participants were selected from two rural North Carolina counties with a high proportion of ethnic minorities and people living below the poverty level.

Participants were interviewed in their homes about their health and use of CAM therapies. Participants were asked if they had used each item for any purpose in the past year and if they had used it specifically for diabetes.

Researchers found that the majority of participants don't use CAM therapies to treat diabetes or other chronic diseases. "They are using CAM for prevention or for treating symptoms (a headache, a sore throat, a cut) but not for treating a chronic condition," wrote the authors. "CAM use among these rural older adults is largely a form of self-care."

It is common to use some of the therapies, such as vinegar or honey, as a general "tonic," says Thomas Arcury, PhD, a professor and lead researcher from Wake Forest University School of Medicine. "I've talked to older adults who'll tell you should take two tablespoons of vinegar every day in a glass of warm water because it's good for you. They aren't treating anything in particular."

The study divided CAM therapies in eight categories to better document which types of therapies are being used. The categories (and examples) are: food home remedies (honey, lemon and garlic), other home remedies (tobacco, Epsom salts, and salves), vitamins (multivitamins, folic acid, and vitamin E), minerals (calcium, magnesium, and zinc), herbs (Gingko biloba, ginseng, and echinacea), popular manufactured products (flax seed, amino acids, and glucosamine sulfate), CAM therapies (imagery, biofeedback, and energy healing), and CAM practitioners (chiropractor, herbalist, and acupuncturist).

More than half of participants used food home remedies (52%) and other home remedies (57%). Vitamins were used by 45% of participants and minerals by 17%. Interestingly, only 6% of participants used herbs for self-care.

Researchers found that ethnicity was the most important personal characteristic in predicting CAM use. African-Americans and Native Americans were 81% and 76% (respectively) more likely to use food home remedies than whites and more than twice as likely to use other home remedies.

The study was funded by the National Institute on Aging and the National Center on Minority Health and Health Disparities.