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Folate-Rich Foods Good for the Brain

By Michael Smith, MedPage Today Staff Writer
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
August 12, 2005

BALTIMORE, Aug. 12 - Folate-rich foods may be good for the brain, suggest findings from the Baltimore Longitudinal Study of Aging.

According to data from the long-running study of aging, eating foods rich in folate - or even adding the B vitamin to the diet with supplements - appears to reduce the risk of Alzheimer's disease.

Participants in the study who typically ate at least the recommended dietary allowance of folate had a 55% reduction in the risk of Alzheimer's, Maria Corrada, Sc.D., of the University of California at Irvine reported in the July issue of Alzheimer's & Dementia, the inaugural edition of the journal.

Other nutrients thought to be beneficial for Alzheimer's - vitamins E and B6 - did not appear to reduce risk, she said. Foods rich in folate include fruits such as oranges and bananas, leafy green vegetables, some peas and beans, and liver.

Dr. Corrada, then at the Johns Hopkins School of Medicine here, and colleagues studied 579 non-demented elderly volunteers, all older than 60. The volunteers filled out diaries showing what they ate and what supplements they took for a seven-day period. Dr. Corrada said the researchers assumed the diaries reflected their typical diets.

"It's a big assumption," she said. "It's still possible that people changed their diets in between."

After an average of more than nine years of follow-up, 57 of the 579 participants developed Alzheimer's, Dr. Corrada said.

The researchers analyzed the recorded nutrient intake of the participants for both anti-oxidant vitamins -- E, C, and carotenoids -- and for B-vitamins -- folate, B6, and B12.

A univariate analysis found a reduced risk of Alzheimer's for folate, vitamin E and vitamin B6, after adjusting for age, gender, education, and caloric intake, Dr. Corrada said.

But in an analysis designed to rule out relations among the variables, only consuming the recommended dietary allowance of folate still had a significant effect. The relative risk was 0.45, with a 95% confidence interval of 0.21 to 0.97.

More research is needed to confirm the results, said William Thies, Ph.D., of the Alzheimer's Association, but the study appears to support recommendations for a "brain-healthy" diet low in fat and cholesterol and high in fruits and vegetables.

Interestingly, only 13% of the study participants reached the recommended dietary allowance of folate - 400 mcg/day - from food alone, Dr. Corrada said; the rest came from supplements. Similarly, only 1% of the participants got their daily allowance of vitamin E from food.

On the other hand, participants had no trouble reaching recommended allowances of the other vitamins by diet alone.

In the U.S., grains are now fortified with folate in an attempt to reduce the rate of neural-tube defects. The program began after the data in this study were taken, but the researchers estimate it would have meant an additional 18% of the study participants would have reached the recommended dietary allowance.

However, that would still have left 47% of the participants below the recommended levels.

Dr. Corrada said the study implies that a diet rich in folate is good for the brain, but she added that it's impossible to rule out other possibilities.

"Because this was an observational study, it is possible that other factors are responsible for the reduction in risk," she said.

In particular, it's likely that "people with a high intake of one nutrient are likely to have a high intake of several nutrients," she said. "And maybe people who have a good diet have other good habits as well."

The bottom line is that people who want to reduce their risk of Alzheimer's should "live a healthy life," she said.

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