The Pharmaceutical Journal
Vol 268 No 7204 p895-899
29 June 2002

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JAMA (jama.ama-assn.org)
British Journal of Psychiatry (bjp.rcpsych.org)

Trials suggest dietary vitamin E reduces Alzheimer's disease risk

Vitamin E from food, but not supplements, may help protect some people against Alzheimer's disease (AD), two new studies suggest.

The first, a population-based study of antioxidant intake among 5,395 subjects, shows that diets rich in foods containing both vitamin E and vitamin C are associated with a lower risk of the disease. Compared with subjects who consumed the lowest levels of vitamin E, subjects who consumed the highest levels had a rate ratio for Alzheimer's disease of 0.57 (95 per cent confidence interval, 0.35–0.91). The corresponding rate ratio for vitamin C intake was 0.66 (0.44–1.00).

The reduction in risk associated with these two vitamins was greatest in current smokers. "Because smoking itself is associated with increased risk of Alzheimer's disease, high antioxidant intake may partly counteract the excess risk of Alzheimer's disease for smokers," the researchers suggest (JAMA 2002;287:3223).

The authors of a second study reveal similar findings and report a link between high dietary intake of vitamin E and protection against Alzheimer's disease. However, they say that vitamin E taken in the form of supplements was not associated with a reduction in the risk of the disease (ibid, p3230).

Commenting on the studies, Dr Neil Buckholtz, National Institute on Aging, National Institutes of Health, United States, said: "The only way this association can really be tested is through clinical studies and trials now under way. These will help us determine whether vitamin E in food or in supplements — or taken together — can prevent or slow the development of mild cognitive impairment or Alzheimer's disease."

He added that it is not recommended, based on current evidence, that people take high-dose vitamin E supplements or other antioxidants in an effort to prevent mental decline. In excessively high doses (above 2,000iu daily), vitamin E may be associated with increased risk of bleeding, and patients taking anticoagulant medicines may be especially at risk. Interactions with other medicines commonly taken by older people are also of potential concern, he said.