Recent reviews by two Harvard University physicians in the Journal of the American Medical Association (JAMA) make a strong case for adults to use a daily vitamin supplement. Meanwhile, a position paper published last year in the Journal of the American Dietetic Association (ADA) emphasizes that decisions about supplements should be based on an accurate appraisal of scientific evidence and individual needs.
Indeed, the Food and Nutrition Board (responsible for setting Recommended Dietary Allowances) and the ADA have identified certain groups most likely to benefit from supplements. Women of childbearing age are urged to get 400 micrograms (mcg) of folic acid from a daily supplement or fortified food to prevent certain birth defects. A daily supplement or fortified food to provide vitamin B-12 is advised for those over age 50 (since age can impair the body's ability to absorb it) and for vegetarians of any age who avoid all animal products. Calcium and vitamin D supplements are recommended for those who avoid or minimize dairy products, and perhaps for those whose needs have increased with age.
The JAMA reports review evidence linking vitamin supplements to a lower risk of chronic disease. They conclude that, while waiting for clearer answers, it would be prudent for adults to take a daily multivitamin supplement. Beyond simply avoiding a deficiency, the authors point to a possible lower risk of heart disease, some cancers and better bone health. As for antioxidant supplements (vitamins E or C, beta-carotene, or lycopene), they emphasize that although many studies link dietary levels with a lower risk of cancer and heart disease, research has shown little if any risk reduction with supplements. The health benefits of antioxidants may be due to their particular forms in foods, to other substances found in foods, or their interactive effect or synergy.
The ADA position paper cautions that supplementation should be based on advice from doctors or dietitians using their expertise to evaluate accumulated knowledge of nutrients, not simply single studies that may be touted by those selling a supplement. Decisions should also be based on individual nutritional needs.
Combining fortified foods and supplements can easily send levels of some nutrients to more than 300 percent of recommended levels. Both the ADA and JAMA reports urge people to be careful that the supplements they take don't exceed the safety levels established as Tolerable Upper Limits. Since they are not printed on food or supplement labels, people considering multiple supplemental sources should check these limits, which are available on the Internet at www.nal.usda.gov/fnic/etext/000105.html.
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Before deciding about a supplement, it's important to consider how many vitamins and minerals you get from fortified foods. Check the Nutrition Facts panel of cereals, snack bars, juices, soy beverages and other drinks to see how the percent of Daily Value for the vitamins and minerals listed actually adds up. If a typical day's food adds up to about 100 percent, you already are taking the equivalent of a vitamin supplement. If you do not use fortified foods often, then a basic supplement providing 100 percent of Daily Value of vitamins and minerals may be an option to consider.
Almost everything recommended by health experts who advocate a supplement can be found in a single generic multivitamin/mineral supplement. Women before menopause should take one that contains iron; men and post-menopausal women, a formula without iron. The only nutrients not covered adequately by such a multivitamin might be calcium and possibly vitamin D.
Never lose sight of the fact that a multivitamin supplement should be an addition to your best efforts to eat a healthy diet rather than an excuse not to bother.