Fish Once a Week Cuts Alzheimer's Risk

July 21, 2003 -- Elderly people who eat fish at least once a week cut their risk of Alzheimer's disease.

Weekly fish eaters had a 60% lower risk of Alzheimer's than people who rarely or never ate fish, find Martha Clare Morris, ScD, of Rush-Presbyterian St. Luke's Medical Center, Chicago, and colleagues. They report the findings in the July issue of Archives of Neurology.

The researchers asked 815 elderly residents of Chicago's South Side to take part in a study. The 65- to 94-year-olds didn't have Alzheimer's disease when the study began in 1993. A couple of years later, they filled out a detailed dietary questionnaire. About four years later, they were tested for Alzheimer's disease.

By then, 131 of the volunteers had developed the brain-wasting illness. But this was 60% less likely to happen to those who ate fish. Analysis of Alzheimer's risk in these patients revealed that it was linked to fatty acids found in fish and other foods.

"Our findings suggest that consumption of fish (at least weekly), oil-based salad dressings and nuts may reduce the risk of Alzheimer disease," Morris and colleagues conclude.

But all the news about fish isn't good. Some toxins found in fish appear to increase the risk of Alzheimer's and other diseases, warns an accompanying editorial by Robert P. Friedland, MD, of Case Western Reserve University School of Medicine, Cleveland.

"The beneficial effects of [fatty acids] from fish may be counterbalanced by toxins," Friedland writes. "Fish may contain dangerous levels of polychlorinated biphenyls and mercury from coal-fired power plants --especially methyl mercury."

Don't gorge yourself on fish or any other particular health food, Friedland advises. Instead, try to eat a healthy, balanced diet.

"A high antioxidant/low saturated fat diet pattern with a greater amount of fish, chicken, fruits, and vegetables and less red meat and dairy products is likely to lower the risk of AD, as well as that for heart disease and stroke," Friedland suggests. "Furthermore, B vitamin supplements, containing vitamins B12 and B6 and folic acid, lower plasma total homocysteine levels, possibly decreasing the risk of stroke, heart disease and perhaps Alzheimer's disease."