Another study showed mild improvement on computerized memory tests in normal older adults taking Omega-3 fatty acids over those taking a placebo. Yet another study showed that women with the highest Omega-3 fatty acids in their blood had a hippocampus 2.7 percent larger and brain volume of 0.7 percent larger than those with the lowest blood levels of Omega-3 fatty acids.
Clearly more research is needed. Presently, no evidence suggests use of Omega-3 fatty acid in supplement form can treat or prevent dementia including Alzheimer's disease (AD), although dietary sources (at least one daily) are encouraged for overall health benefits. The American Heart Association recommends eating fish containing high levels of Omega-3 fatty acids twice a week for heart benefit.
Omega-3 fatty acids are a type of polyunsaturated fatty acid found naturally in certain fatty fish (salmon, herring, sardines, lake trout, and albacore tuna), flaxseed, walnuts, soybeans, kale, spinach, and Brussels sprouts. Because the human body doesn't make omega-3 fatty acids, a person must get them from dietary sources or from over-the-counter supplements, such as fish oil or flaxseed oil.
Research has shown high intake of omega-3 fatty acids can protect against stroke and heart disease.