Tufts doctor questions benefits of multivitamins

More than half the U.S. population takes multivitamins, but there isn't a lot of evidence that they work, says a Tufts University researcher.

Almost 100 years after the first vitamins were named, we still need better advice on whether to take them, particularly when it comes to multivitamins, which "cry out for greater standardization," said Dr. Irwin Rosenberg, director of the Nutrition and Neurocognition Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging.

"The evidence regarding vitamin use for prevention of chronic disease is still quite rudimentary, especially for multivitamins," he said.

Rosenberg made his comments at a National Institutes of Health conference on multivitamins and mineral supplements. They appear in the January issue of the American Journal of Clinical Nutrition.

While scientists know a lot about individual vitamins, Rosenberg said, there is much less known about the effects of taking multiple vitamins together. He called for regulators to pay more attention to the content and labeling of supplements, as well as to how well they might provide adequate nutrients or prevent chronic disease.

"Information relating to individual vitamins or small combinations of vitamins to disease prevention is stronger than that for multivitamins, formulations that cry out for greater standardization," he said.

More than half (52 percent) of the people who take multivitamins say they do so to prevent disease, and more than one-third (38 percent) say they take them because they feel better, studies have shown. But studies also reveal that people who take multivitamins tend to be better educated, weigh less, do more physical activity and eat better diets.

"Since multivitamin users are generally healthier, it might not be feasible to attribute health outcomes to vitamin use until we have more information," he said. "The best source of vitamins is food."