A new study casts doubt on the benefits of taking antioxidant supplements, finding that they are not associated with a longer life. Published in the American Journal of Epidemiology, the study tracked 14,000 retirees (aged 44 to 101) between 1981 and 2013; each retiree filled out a survey detailing their diet and supplement use. In addition, the researchers took into account lifestyle factors that could skew the study results, such as smoking, alcohol intake, caffeine consumption, exercise, body mass index, and histories of certain chronic diseases. Even when taking into account these factors, the researchers concluded that there was no association between the intake of dietary or supplemental vitamin A and C and risk of death, or between supplemental vitamin E and risk of death. Nevertheless, the findings should be viewed with caution for the following reasons:
This was an observational study; observational studies are only capable of looking for associations, and cannot show cause-and-effect. Therefore, the study does not rule out the possibility that some nutritional supplements, including some antioxidant supplements, do prolong life. Randomized controlled trials (which are considered the gold standard of research) have, in fact, shown a decrease in mortality from the use of various nutritional supplements, although the beneficial effects were small and not always statistically significant.
Despite the new findings, there is a substantial amount of evidence that certain antioxidant supplements, such as vitamin C, can be helpful in a number of conditions, including asthma, allergies, colds, depression, high blood pressure, and possibly heart disease. Therefore, even if antioxidant supplements don’t decrease the risk of death, there is reason to believe that they may improve quality of life.
The median age at death of those in the study was 88, suggesting that the study population was unusually healthy to begin with. It is possible, therefore, that antioxidant supplements would have a less positive impact on this group than on the population at large.
Source: American Journal of Epidemiology