NEW YORK (Reuters Health) - Vitamin E intake in food and supplements may help slow decline in mental functioning among older people, according to the results of a study.

"High amounts of vitamin E from foods appears to be protective from cognitive decline," lead author Dr. Martha Clare Morris, assistant professor of internal medicine at Rush-Presbyterian-St. Luke's Medical Center in Chicago, Illinois, told Reuters Health.

The researchers theorized that vitamin E, an antioxidant, may counteract the damage done to brain cells by free radicals, which are byproducts of normal body processes that can damage tissue and have been linked to disease. Previous research has suggested that people who consume more vitamin E retain mental function and are less likely to develop Alzheimer's disease.

To investigate, the researchers studied more than 2,800 US men and women aged 65 to 102. Each was given an initial battery of mental function tests and followed for an average of 3 years, during which they were retested two or three times. They were also asked to fill out a food questionnaire assessing how much of various nutrients they received in their diets and from supplements.

The investigators took into account factors that may influence mental function such as age, gender, education, smoking and drinking.

According to the findings, published in the July issue of the Archives of Neurology, 61% of the study participants showed some decline in their mental function during the course of the study, while 39% had no decline or even improved. The group who reported the highest intakes of vitamin E had a slower decline in mental function than those whose vitamin E intake was lowest.

"There was a 36% reduction in the rate of decline for people in the highest fifth of intake of vitamin E compared to those in lowest fifth of intake," Morris said, referring to intake of the vitamin in both food and supplements.

And those with the highest intake of vitamin E in food had a 32% reduction in their rate of mental decline, compared to those with the least vitamin E in their diets, she said.

For those who took vitamin E supplements, the effect on mental skill was only seen among those who received little vitamin E from their diet, but not in those who already received lots of the vitamin in their diet. "There may be a ceiling effect, and if you taking more, it's not helpful," Morris noted.

However, because the number of people taking supplements during the study doubled, possibly in response to cognitive decline, it was hard for researchers to draw conclusions about whether supplement use was effective on its own in maintaining the brain.

By contrast, vitamin C seemed to have only a limited effect on mental function. "We also don't feel that our data on vitamin C was definitive," Morris said. "The association wasn't consistent."

The team recently reported similar findings for vitamin E and Alzheimer's disease. High intake of the nutrient was linked to a 70% reduction in the risk of developing the disease during a 4-year period. Together, Morris noted, the studies strongly suggest that vitamin E has some protective effect on the brain.

Vitamin E is found in green, leafy vegetables as well as corn, nuts, olives and vegetable oils.

SOURCE: Archives of Neurology 2002;59:1125-1132.

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