Don't Take Your Vitamins?

Wednesday, March 7, 2007

IN LAST WEEK'S issue of the Journal of the American Medical Association, a new study on antioxidant supplements, pills that magazine covers in the 1990s trumpeted as potential miracle drugs for their putative cancer-fighting power, concludes that they do not help users live longer and might even increase the risk of death. It's a reminder that you can't rely just on bottle labels to make smart choices about which pills to take.

A team of scientists performed an exhaustive review of the research on antioxidants, considering 68 trials conducted since 1990 that included more than a quarter-million subjects. After removing studies with a high risk of statistical bias, leaving 47 studies including 180,938 participants, the team found that taking beta carotene, Vitamin A and Vitamin E actually increased the likelihood of death by 5 percent. Vitamin C and selenium did not have any significant effect on mortality. Though fronts for the vitamin industry have tried to pick away at the findings, the data nevertheless generally support the work of a National Institutes of Health conference on multivitamin supplements -- pills packed with antioxidants and other nutrients -- held last May. Then, doctors and researchers concluded that antioxidants appear to have no beneficial health effects except in the cases of a few users with certain conditions, and that they might actually pose a risk to some populations, especially to those individuals who regularly ingest too much of a particular antioxidant supplement.

The next step in the research is determining which antioxidants assist in the treatment of which diseases and which supplements are harmful to which types of patients. Most American adults probably won't see any effect, positive or negative, from taking a daily multivitamin, and participants at the NIH conference did not recommend discontinuing their use. But until reliable data appear to answer those questions, health experts say, consumers can't know for sure what, if anything, sizable doses of antioxidants might do to their health.

Meanwhile, Americans buy about $23 billion worth of dietary supplements every year, and about half of American adults take some kind of supplement. The evidence analyzed last week should lead them to question whether the pills are worth the cost.

© 2007 The Washington Post Company