Vitamin E intake in food and supplements may help slow decline in mental functioning among older people. High amounts of vitamin E from foods appears to be protective from cognitive decline.
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.
According to the findings over 60% of the nearly 3000 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. Vitamin E intake included both vitamin E in 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.
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.
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 the studies strongly suggest that vitamin E has some protective effect on the brain.
Archives of Neurology July 2002;59:1125-1132