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Seafood Keeps Dementia at Bay

Elderly lower risk by eating it at least once a week

THURSDAY, Oct. 24, 2002 (HealthDayNews) -- Don't forget to eat your fish now -- or you might start forgetting later.

A new study has found that elderly people who eat fish or seafood once a week or more had a lower risk of developing dementia, including Alzheimer's disease.

"There is an inverse association," says Dr. Pascale Barberger-Gateau, lead author of the study appearing in the Oct. 26 issue of the British Medical Journal. "The risk of dementia decreased with the frequency of fish consumption."

The fatty acids found in fish have long piqued researchers' interest for their possible role in preventing dementia. There is also some evidence that these polyunsaturated fatty acids (PUFAs), also called omega-3 fatty acids, may help coronary artery disease. Fish that are especially rich in PUFAs are mackerel, salmon, sardines, and tuna.

The objectives of the current study were twofold: to see if there was a relation between consumption of fish (which contains large amounts of polyunsaturated fatty acids) or consumption of meat (high in saturated fatty acids, which tend to raise blood cholesterol) and risk of dementia.

The study looked at data from 1,674 people aged 68 and older who were participating in a large aging study being conducted in 75 parishes in southwestern France. None of the participants had dementia at the start of the study.

The researchers recorded the frequency with which the participants ate meat and fish, then grouped the responses into categories: daily, at least once a week but not every day, from time to time (but not every week), and never. The participants were checked at two, five and seven years after the initial responses were obtained.

By the end of seven years, the researchers observed that people who ate more (at least once a week) fish or seafood had a decreased incidence of dementia. However, there appeared to be no relationship between meat consumption and risk of developing dementia.

Fish or seafood consumption also tended to be higher among people who had more education, raising the possibility that educational level may play a role as well. A relationship between higher educational levels and lower rates of dementia has already been noted.

"The frequency of fish consumption increased with educational level, in these French older people," Barberger-Gateau says. "A high educational level and a high frequency of fish consumption both contributed to a decreased risk of dementia." One theory is that people with more education acquire healthy dietary habits when they are very young.

A previous study had similar results but with a shorter follow-up period (a mean of 2.1 years), which did not leave enough time to see if dementia developed.

If the polyunsaturated fatty acids do indeed play a role in preventing dementia, it could be due to a number of different mechanisms. The fatty acids in fish oils may reduce inflammation in the brain or they may be involved in regeneration of nerve cells.

The role of polyunsaturated fatty acids is still far from certain.

"The data looked reasonably consistent and it looks like they have a pretty positive effect so it's certainly an interesting formation," says Dr. Ellen Drexler, associate attending neurologist at Maimonides Medical Center in Brooklyn, N.Y. "Are we going to tell all our patients to run out and eat fish every night? I don't think so. It may just be correlations with other good health habits, though there is some biological plausibility."

What To Do

Check out the American Geriatrics Society for information on dementia. Meanwhile, try the American Heart Association to learn about other health benefits of fish and fish oil.

SOURCES: Ellen Drexler, M.D., associate attending neurologist, Maimonides Medical Center, Brooklyn, N.Y.; Pascale Barberger-Gateau, M.D., Ph.D., senior lecturer, University Victor Segalen Bordeaux, Bordeaux, France; Oct. 26, 2002 British Medical Journal
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