Large Study Points to the Brain Benefits of Eating Fish
Many studies have suggested that a diet rich in fish is good for the heart. Now there is new evidence that such a diet may ward off dementia as well. One of the largest efforts to document a connection — and the first such study undertaken in the developing world — has found that older adults in Asia and Latin America were less likely to develop dementia if they regularly consumed fish.
And the more fish they ate, the lower their risk, the report found. The findings appeared in the August issue of The American Journal of Clinical Nutrition.
The study, which included 15,000 people ages 65 and older in China, India, Cuba, Venezuela, Mexico, Peru and the Dominican Republic, found that those who ate fish nearly every day were almost 20 percent less likely to develop dementia than those who ate fish just a few days a week. Adults who ate fish a few days a week were almost 20 percent less likely to develop dementia than those who ate no fish at all.
“There is a gradient effect, so the more fish you eat, the less likely you are to get dementia,” said Dr. Emiliano Albanese, a clinical epidemiologist at King’s College London and the senior author of the study. “Exactly the opposite is true for meat,” he added. “The more meat you eat, the more likely you are to have dementia.” Other studies have shown that red meat in particular may be bad for the brain.
Fish, especially oily fish, may be protective against dementia because it is rich in omega-3 long-chain polyunsaturated fatty acids, which studies suggest may have numerous health benefits, among them anti-inflammatory properties. Omega-3 fatty acids have been shown in animal studies to reduce the build-up of atherosclerotic plaques and may also prevent the accumulation of amyloid plaques in the brain characteristic of Alzheimer’s disease, Dr. Albanese said.
But though numerous observational studies in the West also have indicated fish may reduce dementia risk, there is little evidence as yet from randomized controlled clinical trials, which provide the best scientific evidence but are expensive and difficult to carry out.
Although the new study was an observational study, Dr. Albanese suggested that since the findings are consistent both in the West and in developing countries, where the environment and lifestyle are so different, the new data lend support to the hypothesis that fish is protective against dementia.
Most of the elderly surveyed in the study lived with extended families, and those seniors who had electricity and indoor plumbing, or several assets like a car, a phone, a TV or a refrigerator were considered relatively well off.
Researchers assessed the dietary habits of 14,960 study participants by going door-to-door to do face-to-face interviews, and they diagnosed dementia by using culturally validated criteria. The data were adjusted to account for differences in such variables as sex, age, education, income, smoking and physical health.
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