There has been much ballyhoo in recent years over the potential health benefits of antioxidant nutrients, such as vitamins E and C. They are thought to counteract the harmful effects of so-called "free radicals" - molecules that can damage cells in the body and thereby increase the risk for chronic diseases, such as heart disease and cancer. Free radicals might also affect mental functioning and may contribute to the mental decline that is associated with aging. A recent study suggests that taking antioxidant supplements may help stave off age-related mental decline. The results are published in the American Journal of Clinical Nutrition.

Studying aging female nurses

Researchers studied almost 15,000 female nurses participating in the Nurses' Health Study. Beginning in 1980, they collected data on several of the nurses' lifestyle factors, including the use of vitamin E and vitamin C supplements. From 1995-2000 they then administered, by phone, cognitive function examinations - tests of mental performance - to the women who were 70-79 years of age at that time.

The researchers performed statistical analyses to determine if prior and/or current use of vitamin supplements had any association with mental function. In doing so, they allowed for other factors that could potentially influence the outcome, such as education level, smoking, high blood pressure, and cardiovascular disease.

Long-term use of vitamins E plus C shows the most benefit

Women who were currently taking supplements of both vitamin E and vitamin C and had done so for several years performed better on the cognitive function test compared with women who had never taken vitamin E or C supplements. Longer duration of supplement use was associated greater benefit. The benefit of supplement use was strongest among women who had low amounts of vitamin E in their diets, and was less pronounced among women taking just vitamin E with no vitamin C. There was no benefit observed among women taking just vitamin C.

How antioxidants might work

The exact mechanisms by which antioxidants may improve mental function have yet to be fully explained. There are probably a variety of biochemical bodily processes involved. For example, it may have something to do with the health of the arteries that supply blood to the brain.

Keeping it in perspective

It's important to remember that this was an observational study, meaning that the researchers didn't give subjects any particular treatment - they just observed what happened when some women took supplements by their own choice and others did not. Therefore, these results cannot prove that antioxidant supplements actually cause improvement in mental function - only that they are associated with improvement in mental function.

The women who took supplements may have been healthier overall, and that might have played a role in their better mental function. Also, this study's subjects are a fairly similar group of people, and the results can't necessarily be applied to men or to people of other ages or different education levels.

Still, these results add to the evidence that antioxidant supplements may benefit health, and they may lead to randomized clinical trials studying the use of antioxidants in preventing mental decline.

If you're thinking about taking antioxidant supplements, be sure to consult your doctor first, to make sure you don't have any conditions or take any medications that may interact with the supplements, or trigger potentially harmful side effects.