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For many years I began each day ingesting fish oil, adding my contribution to the $30 billion industry of dietary supplementation. I stopped when the available evidence did not support its benefits for people not at high risk for cardiovascular disease. (Fish oil supplements may be reasonable for some people after a heart attack.)
Half of American adults consume at least one dietary supplement daily, 48% swallowing vitamins and 39% ingesting minerals, hoping to maintain health and ward off disease. Many do so because their daily pressures prevent them from eating a healthful and balanced diet, and they rationalize that the supplements will provide nutrition absent from their fast food regimen.
But is that true? Most randomized clinical trials of vitamin and mineral supplements have not demonstrated clear benefits in preventing chronic diseases unrelated to nutritional deficiency. In fact, ingesting vitamins and minerals in amounts exceeding the recommended daily allowance may actually be harmful, increasing mortality, cancer, and strokes. Some supplements can counteract the beneficial action of specific medications. In most cases, dietary supplements provide little if any benefit beyond that obtained in a nutritious diet.
Also, the nutrients in food usually are better absorbed by the body, are associated with fewer potential adverse effects, and provide optimal and balanced amounts as opposed to ingesting isolated compounds in highly concentrated form. Positive health outcomes are more strongly related to dietary patterns and foods than to individual supplements.
It’s also important to remember that the Food and Drug Administration does not review dietary supplements for safety and efficacy and, while manufacturers must adhere to Good Manufacturing Practice regulations, compliance monitoring may be less than optimal. A good practice is to choose a supplement certified by an independent tester who verifies that the supplement contains the labeled doses and is not contaminated with microbes, heavy metals or other toxins. Check the website of the Office of Dietary Supplements of the National Institutes of Health for accurate information.
While routine supplementation is not recommended for the general public, diet alone may not provide the necessary nutritional requirements in some groups. Pregnant women need higher amounts of folic acid and prenatal vitamins, and some mid-life and older adults require supplemental vitamin B12 and vitamin D. Calcium is best obtained by calcium-rich foods, with calcium supplements used only if the daily goal is not met. A recent analysis of multiple randomized trials found that supplements that included calcium, vitamin D, or both compared with placebo or no treatment was not associated with a lower risk of fractures among community-dwelling older adults. I have often joked that the urine of many Americans has the highest concentration of vitamins found anywhere, since multivitamin/multimineral supplementation is not recommended for generally healthy adults and the excess is just excreted.
A final word: be sure to tell your doctor about any dietary supplement you are taking to be certain it is compatible with your other medications and overall medical condition.