Vitamins Tied to Reduced Risk of Alzheimer's

Source: Tufts University
August 8, 2002 (Reviewed: August 20, 2004)

Can an antioxidant-rich diet help slow the progression of debilitating conditions like Alzheimer's disease (AD)? Research suggests a protective role for several key antioxidants, notably vitamin E, but a clear link between diet and mental functioning has yet to be established. Two studies published in a recent issue of the Journal of the American Medical Association add to what scientists know of this complex issue.

Looking at diet

In one analysis, 815 Chicago area residents --- all at least 65 years old and free of clinical signs of dementia --- were followed for an average of 4 years. Food frequency questionnaires completed during the study were used to assess usual intake of vitamins C and E and beta-carotene from food and dietary supplements.

A total of 131 participants were diagnosed with AD during the study. After adjusting for potential factors known to affect risk --- including age, gender, and education level --- the researchers found that those who consumed the most vitamin E from foods (over 50 IU/day) were 70% less likely than those who consumed the least (less than 7.9 IU/day) to develop Alzheimer's disease. Vitamin E from dietary supplements, however, did not have the same effect. Likewise, vitamin C and beta-carotene intake had no significant effect on risk.

A second study followed more than 5000 Dutch residents --- all at least 55 years old and deemed free of dementia --- for an average of 6 years. Again, food frequency questionnaires were used to assess usual diet. During the study's span, 146 people developed AD. The researchers found that those with the highest intake of vitamin C from foods and supplements were 18% less likely than those with the lowest intake to develop AD. High intake of vitamin E from foods and supplements was also associated with a reduced disease risk, although not to as great as an extent as with vitamin C.

What's the connection?

The antioxidant-brain health connection seems obvious --- the brains of Alzheimer's victims clearly show signs of damage associated with exposure to free radicals, oxygen-containing molecules that are produced during normal cell functions. Antioxidants help to limit such cell damage by deactivating free radicals. But it remains to be seen if consuming a high antioxidant diet can have a measurable effect on the risk of developing a multi-faceted disease like Alzheimer's.

Why didn't supplements have more of an effect?

Earlier research has suggested that antioxidant supplements, especially vitamin E, may be able to slow the mental decline that marks Alzheimer's, but supplements did not appear to have a major impact in these studies. It's not clear why, but the study may have been too short in duration and may have not captured enough data on long-term supplement use.

Advice to consumers

More work needs to be done to give researchers a clear picture of which nutrients, in what amounts, might help reduce Alzheimer's risk. Note, though, that in these studies, participants who consumed the most antioxidants from foods were likely eating a variety of fruits, vegetables, whole grains, seeds, and nuts. Such a diet tends to be high in vitamins, minerals, and phytochemicals --- any combination of which may help keep you healthy as you age.

Sources

• Dietary intake of antioxidants and risk of Alzheimer's disease. M. Engelhart, M. Geerlings, A. Ruitenberg,  et al., JAMA , 2002, vol. 287, pp. 3223--3229



• Dietary intake of antioxidant nutrients and risk of incident Alzheimer's disease in a biracial community study. M. Morris, D. Evans, J. Bienias,  et al., JAMA , 2002, vol. 287, pp. 3230--3237

Related Links
Risk Factors for Alzheimer's
Oxidative Damage, Part III: Nature's Approach to Protection
How to Increase Your Intake of Fruits and Vegetables
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