But the promise of high-dose vitamin pills has been increasingly contradicted by scientific research, Lichtenstein wrote in The Journal of the American Medical Association late last month, with a Tufts colleague. For example, consider beta carotene. It was trumpeted as the ultimate cancer fighter. But researchers in one study showed that high doses of the nutrient, which the body converts to vitamin A, actually increased the chance that a smoker would develop lung cancer. Then there’s folate. Physicians still encourage women trying to get pregnant to take supplements that include folate because of scientific studies showing it prevents birth defects.
But recent findings have tempered hopes that folate would also help battle heart disease, and one study suggested that heart patients who took large amounts of folate after an operation to unclog their arteries were more likely to get clogs again. And the vitamin E report, appearing in The Journal of the American Medical Association, concluded that for most women, large doses of vitamin E do nothing to prevent heart problems. The studies debunking the disease-preventing powers of vitamins have come under steady attack, both from the supplement industry and from vitamins aficionados. The Dietary Supplement Education Alliance, an industry-backed advocacy coalition, regularly assails studies critical of vitamins, arguing that the science is faulty and that it is tantamount to fear-mongering.