Johns Hopkins Health Alerts | Nutrition and Weight Control | Omega-3 Protects Alzheimer’s Disease

• In a recent study those who ate fish twice weekly reduced their risk of developing Alzheimer’s disease by 70%

Omega-3 fatty acids, which are abundant in fish, are known to play a role in protecting the heart. But now another benefit of these polyunsaturated fatty acids has turned up: People who consume omega-3 fatty acids also have a reduced risk of developing Alzheimer’s disease, according to a study in the Archives of Neurology.

Among 815 older Chicago residents without dementia, those who consumed fish once a week were 60% less likely to develop Alzheimer’s disease after four years than people who rarely or never ate fish. For those who ate fish twice weekly, the risk of developing Alzheimer’s disease was reduced by 70%.

Fish is a rich source of two types of omega-3s: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Another omega-3, alpha linolenic acid (ALA), is found mainly in plant oils and nuts, particularly canola, soybean, and flaxseed oils, as well as walnuts.

In the study, the participants completed dietary questionnaires, and the investigators calculated how much of the three omega-3s each person consumed. Most of the protective effect of omega-3s was from DHA. EPA had no significant effect, and ALA reduced the Alzheimer’s disease risk only in people with a genetic predisposition for Alzheimer’s disease.

As in all epidemiological studies, the benefit demonstrated here needs confirmation. But these results support the recommendation for regular inclusion of omega-3–rich foods in the diet.

So-called fatty fish such as herring, sardines, salmon, mackerel, trout, halibut, and tuna contain more omega-3 fatty acids than “lean” species such as cod or haddock. Although more research is needed to establish recommended daily intake values, the American Heart Association suggests eating at least two 3-ounce servings of seafood (preferably fatty species) weekly to gain a cardioprotective effect.

Johns Hopkins Health Alerts | Nutrition and Weight Control | Omega-3 Protects Alzheimer’s Disease