Getting your daily dose of essential vitamins and minerals from the foods you eat is still better for you than taking nutritional supplements that promise to prevent disease, according to new research.
Researchers say the identification of individual nutrients in food that appeared to fight disease initially raised the possibility that people could optimize their health through nutritional supplementation.
But recent attempts to use this approach to prevent diseases such as heart disease and lung cancer with nutritional supplements containing vitamin E and beta-carotene have produced disappointing results. Health risks associated with taking too much of certain vitamins, such as high doses of vitamin A and D and minerals, have also emerged.
Instead, researchers say the most promising research in nutrition and preventing disease now relates to dietary patterns, not nutritional supplements.
"There are good data to suggest that certain dietary and lifestyle patterns are associated with decreased risk of chronic disease. However, providing nutrient supplementation to mimic these effects has failed to result in the efficacy that was initially anticipated," write Alice H. Lichtenstein, DSc, and Robert M. Russell, MD, of Tufts University in the current issue of The Journal of the American Medical Association.
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In their report, they say strong research shows a relationship between certain dietary patterns and decreased disease risk, such as diets high in fruits, vegetables, and grains and heart disease.
However, rather than focusing on dietary patterns, most intervention studies have used high doses of a particular nutrient or cocktail of nutrients delivered through supplements in an attempt to fight disease.
Researchers say that for the most part the results of these nutritional supplement studies have been disappointing and cite several examples, including:
— Studies of vitamin E supplementation that failed to reduce heart disease risk.
— A series of studies showed that supplementation of beta-carotene, found in deeply colored fruits and vegetables, did not reduced the risk of lung cancer as had been hoped.
— Ongoing studies that show folic acid (found naturally in leafy greens as folate) supplementation does not reduce the risk of hardening of the arteries.
Meanwhile, health risks or potentially dangerous nutrient interactions associated with excessive supplementation of certain nutrients, such as vitamin E, calcium, and folic acid, have also become apparent.
"These findings suggest that science is not at a point at which researchers can identify with relative certainty the putative compounds that are driving the food-disease relationship," write the researchers.
Therefore, with the exception of certain groups that can benefit from targeted nutritional supplementation, researchers say it's still too soon to shift the focus from eating a well-balanced diet to meet people's nutritional needs and promote optimum health to recommending nutritional supplements for the general public.
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By Jennifer Warner, reviewed by Brunilda Nazario, MD
SOURCE: Lichtenstein, A. The Journal of the American Medical Association, July 20, 2005; vol 294: pp 351-358.
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