A recent systematic review and meta-analysis of clinical studies by European researchers led them to conclude that taking antioxidant supplements either has no effect on health or can slightly increase mortality in some cases. The results of this analysis were published in the Feb. 28 issue of The Journal of the American Medical Association (see http://jama.ama-assn.org/cgi/content/abstract/297/8/842).
Over the course of their analysis, the researchers investigated 68 studies involving 232,606 people. The researchers sought to determine the effect of antioxidant supplements on mortality by searching electronic databases and bibliographies. All randomized trials involving adults comparing beta carotene, vitamin A, vitamin C, vitamin E, and selenium—either by themselves or combined with. placebos or no intervention—were included in the analysis.
The net result was that no health significant effect can be linked to taking antioxidant supplements. In some levels of analysis, the researchers actually found a higher risk of death for people taking the supplements—particularly supplements based on vitamin E, beta carotene and vitamin A. However, they note that the actual cause of death in most studies remains unknown, and some experts who have reviewed these findings suggest that the researchers were inappropriately pooling diverse studies. Regardless, Dr. Christian Gluud, of the Centre for Clinical Intervention Research at Copenhagen University Hospital and the study’s senior author, notes: “The main message is that prevention by beta carotene, vitamin A and vitamin E cannot be recommended. These three antioxidant supplements may increase mortality.” Other institutions taking part in this analysis were the Department of Internal Medicine, Gastroenterology and Hepatology at the University of Nis, Serbia, and the Divisione di Medicina, Ospedale V. Cervello, Palermo, Italy.
The researchers concluded that use of dietary supplements beta carotene, vitamin A, and vitamin E may increase mortality, while noting that “the potential roles of vitamin C and selenium on mortality need further study.”
