Some Americans May Get Too Many Nutrients

Amid concern that some people take too many dietary supplements, the National Institutes of Health today released preliminary recommendations that generally urge caution.

The statement from the agency, part of the U.S. Department of Health and Human Services, concerns multivitamin and mineral supplements, collectively called MVMs. Conclusions were reached by a 13-member independent panel working for the agency.

"Half of American adults are taking MVMs and the bottom line is that we don't know for sure that they're benefiting from them," said J. Michael McGinnis, chair of the panel from the Institute of Medicine of the National Academy of Sciences, who chaired the panel. "In fact, we're concerned that some people may be getting too much of certain nutrients"

The findings pertain to the generally healthy population and do not include pregnant women, children, or those with disease.

The panel recommends:

  • Combined use of calcium and vitamin D supplementation for postmenopausal women to protect bone health.
  • Anti-oxidants and zinc should be considered for use by non-smoking adults with early-stage, age-related macular degeneration, an eye condition that can cause blindness.
  • Women of childbearing age should take daily folate to prevent birth defects of the brain and spinal cord.

The researchers found no evidence to recommend beta carotene supplements, a form of vitamin A, for the general population, and strong evidence to caution smokers against taking them. Beta-carotene has been linked to an increase in lung cancer among smokers who took it regularly.

In looking specifically at MVMs for chronic disease prevention, the panel found that the available data are insufficient to make a firm recommendation for or against their use in the general population.

Health conscious people are the most likely to consume MVMs, which makes it difficult to determine whether MVMs, exercise, diet or other factors are responsible for their good health, the panel concluded.

Despite the general pubic perception that MVMs are safe, the panel identified several possible risks. Too much of certain nutrients can have adverse effects, the scientists said. And the combined effects of eating fortified foods, taking MVMs, and consuming single vitamins or minerals in large doses can lead to overconsumption.

The panel urged changes in the regulation of MVMs and other dietary by the Food and Drug Administration (FDA). Specifically, the panel recommended that Congress expand FDA's authority and resources to require manufacturers to disclose adverse events, to ensure quality production, and to facilitate consumer reporting of adverse events by including reporting information on dietary supplement labels.

The panel included experts in the fields of food science and human nutrition, biostatistics, biochemistry, toxicology, geriatric medicine, family medicine, pediatrics and pediatric endocrinology, cancer prevention, epidemiology, disease prevention and health promotion, and consumer protection.