Can Multivitamin and Minerals Supplements Prevent Chronic Disease?

This week, an independent panel convened by NIH assessed the available evidence on the safety and effectiveness of multivitamin/mineral supplements (MVMs). They made recommendations about some supplements, but concluded that more rigorous scientific research is needed before strong recommendations could be made about using MVMs to prevent chronic diseases.

"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. In fact, we're concerned that some people may be getting too much of certain nutrients," said panel chair Dr. J. Michael McGinnis of the National Academy of Sciences.

The 13-member panel included experts in a wide range of fields from nutrition and medicine to consumer protection. Before its deliberations, the panel reviewed pertinent research from the published literature, listened to 2 days of expert presentations and considered comments and concerns from conference participants.

The panel recommended the use of calcium and vitamin D supplements for postmenopausal women to protect bone health. It also recommended that anti-oxidants and zinc be considered for use by non-smoking adults with early-stage, age-related macular degeneration. The panel supported previous recommendations by its sister agency, the Centers for Disease Control and Prevention, that women of childbearing age take daily folate to prevent birth defects of the brain and spinal cord. Conversely, it found no evidence to recommend beta carotene supplements (a form of vitamin A) for the general population and strong evidence to caution smokers against them; smokers who took the vitamin regularly had a higher risk of getting lung cancer.

The panel identified several possible risks associated with MVMs, including the risk of consuming too much of certain nutrients. Health-conscious people are likely to be focused on ensuring they meet the recommendations for essential nutrients. However, the combined effects of eating fortified foods and various supplements may lead them to unwittingly exceed the Upper Levels (ULs) of nutrients, which can be harmful.

The available data were insufficient for the panel to make a firm recommendation about MVMs for chronic disease prevention in the general population. MVM use is highest among those who engage in other positive health behaviors such as regular exercise and healthy eating. That makes it difficult to tease out which factors are truly responsible for improvements in health. The panel made several specific recommendations about possible future research directions to shed more light on MVMs.