By Alan R. Gaby, MD
Healthnotes Newswire (May 25, 2006)—Is that vitamin supplement you take every day doing you any good? Could it be harming you? Because more than half of American adults use multivitamins, the National Institutes of Health commissioned a panel of experts to convene for three days to seek answers to these questions by reviewing the scientific evidence on the benefits and risks of taking vitamins and minerals.
The panel limited their evaluation mainly to large, randomized clinical trials that looked at common diseases such as cancer, heart disease, and osteoporosis. The report concluded that “there are few rigorous studies upon which to base clear conclusions and recommendations” and that “the present evidence is insufficient to recommend either for or against the use of MVMs [multivitamin-mineral supplements] by the American public to prevent chronic disease.” They also concluded that there is no strong evidence that vitamin and mineral supplements prevent cancer or heart disease, but that calcium and vitamin D can prevent bone loss and fractures. In addition, they noted that supplementing with zinc, vitamin C, vitamin E, and beta-carotene may slow the rate of visual decline in people with age-related macular degeneration.
These experts might have reached a different conclusion had they used broader definitions of “evidence” and “chronic disease.” A lack of strong evidence regarding cancer and heart disease is not the same as a lack of evidence. One clinical trial found that supplementing with 200 mcg of selenium per day decreased the risk of lung, colon, and prostate cancer. And there is a great deal of research suggesting that vitamin C, magnesium, B vitamins, chromium, selenium, copper, and other nutrients can help prevent heart disease. While these studies are not definitive, had the panel considered all of the evidence, they might reasonably have concluded that certain nutrients might help prevent cancer and heart disease.
Similarly, vitamin and mineral supplements can provide many other health benefits not covered by the panel’s report, which was limited to a discussion of major chronic diseases. For example, studies have shown that magnesium and riboflavin can prevent migraine headaches; biotin can help fingernails become stronger; vitamin B6, vitamin E, and magnesium can improve premenstrual syndrome symptoms; vitamin D can improve mood; vitamin B6 and magnesium can prevent kidney stones; and vitamin C and flavonoids can improve the health of gum tissue. Many people feel that various vitamin and mineral supplements give them more energy, prevent muscle aches or cramps, improve sleep, or generally make them feel better. These benefits have not been well documented by research studies, but are widely believed.
As noted in the report, vitamin and mineral supplements are not entirely safe. For example, beta-carotene can increase the risk of lung cancer in smokers. Adverse effects have also occurred with high doses of vitamin A, niacin, and zinc, but the amounts of these nutrients present in multivitamin-mineral preparations is usually well below the doses that have caused adverse effects.
As with all substances that can influence our health, people should educate themselves and seek the advice of a qualified practitioner regarding the safety and appropriate doses of the nutrients they wish to take, as well potential drug interactions. When these precautions are taken, the benefits of taking vitamins and minerals probably outweigh the risks for most people.
An expert in nutritional therapies, Chief Medical Editor Alan R. Gaby, MD, is a former professor at Bastyr University of Natural Health Sciences, where he served as the Endowed Professor of Nutrition. He is past-president of the American Holistic Medical Association and gave expert testimony to the White House Commission on Complementary and Alternative Medicine on the cost-effectiveness of nutritional supplements. Dr. Gaby has conducted nutritional seminars for physicians and has collected over 30,000 scientific papers related to the field of nutritional and natural medicine. In addition to editing and contributing to The Natural Pharmacy (Three Rivers Press, 1999), and the A–Z Guide to Drug-Herb-Vitamin Interactions (Three Rivers Press, 1999), Dr. Gaby has authored Preventing and Reversing Osteoporosis (Prima Lifestyles, 1995) and B6: The Natural Healer (Keats, 1987) and coauthored The Patient's Book of Natural Healing (Prima, 1999).
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