Fish oil is a source of omega-3 fatty acids in the diet. Your body needs omega-3 fatty acids for many functions, from muscle activity to cell growth. Omega-3 fatty acids come from food. They cannot be made in the body. Omega-3 fish oil contains both docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Omega-3 fatty acids are essential nutrients that are important in the prevention and treatment of heart disease. Omegas and fish oil are good for lowering blood pressure, reducing triglycerides, slowing the development of plaque in the arteries, reducing the risk of abnormal heart rhythms, reducing the likelihood of heart attack and stroke, and reducing the risk of sudden cardiac death in people with heart disease.