An independent panel convened this week by the NIH Office of Medical Applications of Research and the Office of Dietary Supplements assessed the available evidence on the safety and effectiveness of multivitamin/minerals (MVMs).
Following two days of expert presentations, public discussion, and panel deliberations, the panel made recommendations regarding certain specific supplements but ultimately concluded that more rigorous scientific research is needed before strong recommendations can be made regarding MVM use to prevent chronic diseases.
The panel released a draft statement of its findings this morning, at the close of the conference. The panel's findings pertain to the generally healthy population, and do not include pregnant women, children, or those with disease. Full text of the panel's draft state-of-the-science statement will be available late today at http://consensus.nih.gov. The final version will be available at the same Web site in four to six weeks.
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 J. Michael McGinnis, M.D., M.P.P., Senior Scholar with the Institute of Medicine of the National Academy of Sciences, who chaired the panel.
The panel recommended the combined use of calcium and vitamin D supplementation for postmenopausal women to protect bone health. The panel also advocated that anti-oxidants and zinc be considered for use by non-smoking adults with early-stage, age-related macular degeneration, an eye condition that can cause blindness. The panel supports previous recommendations by the CDC that women of childbearing age take daily folate to prevent neural tube defects (birth defects of the brain and spinal cord) in infants. 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 taking them. Specifically, beta-carotene was linked to an increase in lung cancer among smokers who took the vitamin regularly.
In looking specifically at MVMs for chronic disease prevention, however, the panel found that the available data are insufficient to make a firm recommendation for or against their use in the general population.
Of note, rates of MVM use are highest among those who engage in other positive health behaviors such as regular exercise and eating a healthier diet, making it difficult to determine whether the MVM alone is truly responsible for any observed improvement in health.
Most of the public assumes that the components of MVM supplements are safe, because many of the ingredients are found in everyday foods and the products are available over-the-counter. The panel identified several possible risks associated with MVM consumption, however. Among these is the potential for overconsumption of certain nutrients, with the resulting possibility of adverse effects. Though health-conscious individuals are likely to be focused on ensuring that they meet the recommendations for essential nutrients, the combined effects of eating fortified foods, taking MVMs, and consuming single vitamins or minerals in large doses, may lead them to unwittingly exceed the Upper Levels (ULs) of nutrients, which can be harmful.
Given these safety concerns and the limitations of the available evidence, the panel advocated for changes in the regulation of dietary supplements — including MVMs — by the Food and Drug Administration (FDA). Specifically, the panel recommends 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 also made several specific recommendations regarding future research, including but not limited to the following:
- Design and conduct rigorous randomized, controlled trials of the impact of individual supplements to test their efficacy and safety in prevention of chronic disease, using well-validated measures
- Build new MVM databases that detail the exact composition of supplements, update them on a continuous basis, and assure their constant availability to the research community
- Develop a strategy to support a better understanding of possible interactions between MVMs and prescribed or over-the-counter medications.
The 13-member 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. A brief biography on Dr. McGinnis is available at http://www.iom.edu/?id=28194. A listing of the panel members and their institutional affiliations is included in the draft conference statement.
In addition to the material presented at the conference by speakers and the comments and concerns of conference participants presented during discussion periods, the panel considered pertinent research from the published literature and the results of a systematic review of the literature commissioned by the NIH Office of Medical Applications of Research (OMAR). The systematic review was prepared through the Agency for Healthcare Research and Quality (AHRQ) Evidence-based Practice Center (EPC) program, by the Johns Hopkins University Evidence-based Practice Center. The EPCs develop evidence reports and technology assessments based on rigorous, comprehensive syntheses and analyses of the scientific literature, emphasizing explicit and detailed documentation of methods, rationale, and assumptions. The evidence report on Multivitamin/Mineral Supplements and Prevention of Chronic Diseases is available at http://www.ahrq.gov/clinic/tp/multivittp.htm.
The panel's statement is an independent report and is not a policy statement of the NIH or the federal government. The NIH Consensus Development Program, of which this conference is a part, was established in 1977 as a mechanism to judge controversial topics in medicine and public health in an unbiased, impartial manner. NIH has conducted 118 consensus development conferences, and 27 state-of-the-science (formerly "technology assessment") conferences, addressing a wide range of issues. A backgrounder on the NIH Consensus Development Program process is available at http://consensus.nih.gov/forthemedia.htm.