Fish Oil & Omegas for Heart & Cognitive Health. Omega-3 fatty acids, found in cold-water fish (fish oil), chia and flaxseed, are essential to a healthy diet. Omega-3s include eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are usually lacking in a typical Western diet filled with foods containing high amounts of omega-6 fats.