July 22, 2010 — Vitamin E may play a modest role in altering the course of dementia, say researchers. Compared with participants with the lowest intake, investigators found that those patients with higher vitamin E intake were 25% less likely to develop dementia.
"When beta-amyloid — a hallmark of pathologic Alzheimer disease — accumulates in the brain, an inflammatory response is likely evoked that produces nitric oxide radicals and downstream neurodegenerative effects," report investigators led by Elizabeth Devore, ScD, from the Erasmus Medical Center in Rotterdam, the Netherlands. "Vitamin E is a powerful fat-soluble antioxidant that may help to inhibit the pathogenesis of dementia."
|Number of Alzheimer cases by dietary vitamin E intake.|
The results appear in the July issue of the Archives of Neurology and suggest that dietary antioxidants affect the early stages of dementia.
Vitamin E is found in whole-grain foods, eggs, milk, nuts, seeds, avocado, spinach, and unheated vegetable oils. The Rotterdam Study previously found that higher dietary intakes of vitamins E and C were associated with a lower risk for dementia and Alzheimer's disease.
In this new long-term follow-up of the Rotterdam Study, investigators followed participants for 9.6 years. The population-based prospective cohort study included 5395 people free of disease at baseline.
A total of 465 people developed dementia. Of these, 365 were diagnosed with Alzheimer's disease. The investigators found that higher dietary intake of vitamin E, but not vitamin C, beta carotene, or flavonoids, was associated with lower long-term risk for dementia.
These results conflict with previous findings, which suggested a link between vitamin C intake and dementia risk. "The result was modest in our analysis," note the investigators, who reported a hazard ratio of 0.66 (95% confidence interval, 0.44 - 1.00). "Chance is the most likely explanation," they add. "Alternatively, vitamin C intake could be important exclusively at later stages of dementia development, but this is less likely because results of previous studies suggest that dietary antioxidants affect early stages of dementia pathogenesis."
Long-Term Prospective Study
The investigators adjusted for age, education, apolipoprotein E ε4 genotype, total energy, alcohol intake, smoking habits, body mass index, and supplement use. They found that higher vitamin E intake at study baseline was associated with lower long-term risk for dementia (P = .02 for trend).
Asked by Medscape Medical News to comment, Maria Carrillo, PhD, senior director of medical and scientific relations at the Alzheimer's Association, pointed out the National Institutes of Health have been calling for long-term prospective studies such as this one. "These are important studies, and this one was conducted by a fantastic, internationally renowned group."
Dr. Carrillo acknowledged the finding is preliminary — it is still too early for specific recommendations on vitamin E intake, and excessive use can have negative cardiovascular effects, she said.
"Future studies should continue to evaluate dietary intake of antioxidants relative to dementia risk," note the investigators, "including different points at which antioxidant intake might modulate risk."
This study was supported by the Netherlands Organization for Scientific Research, the National Institutes of Health, and a US Fulbright Fellowship to the Netherlands. The researchers have disclosed no relevant financial relationships.
Arch Neurol. 2010;67:819-825. Abstract
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