If fish does protect the aging brain, researchers believe that the benefits probably come from the omega-3 fatty acids found most abundantly in oily fish like salmon, mackerel and albacore tuna.
Lab studies show that omega-3 fats have a number of properties that could help stave off dementia -- including actions that protect nerve cells, limit inflammation and help prevent the build-up of the amyloid proteins seen in the brains of Alzheimer's patients.
These latest findings are based on surveys of 14,960 adults age 65 or older living in China, India, Cuba, the Dominican Republic, Mexico, Peru or Venezuela.
It’s true. Fish is high in brain-building fat, but Dr. Fuhrman points out most varieties of fish—especially tilefish and mackerel—are heavily polluted with mercury. Dr. Fuhrman’s DHA Purity is a contamination-free omega–3 fatty acid supplement, but if you must have fish, here’s Dr. Fuhrman’s opinion on it.
Choose fish over other animal products, but be aware that the place where it was caught, and the type of fish, matters. Don't accept recreational fish from questionable waters. Farmed fish is safer. Never eat high-mercury-content fish. Don't eat fish more than twice a week, and if you have a family history of hemorrhagic stroke, limit it further to only once a month.