People take them to prevent premature death, improve cardiovascular health and prevent cancer, but little evidence supports this. Omega-3 fatty acid supplements prevent heart attack and heart-related sudden death in people with a history of cardiovascular disease. They might also promote mental health by preventing depression and brain inflammation.  Omega-3’s might prevent muscle loss with age. Scottish researchers gave older adult six grams of fish oil per day or a placebo (fake fish oil) for nine months. The Omega-3 fatty acids promoted muscle protein synthesis and helped aging people maintain muscle mass, but had no effect on blood sugar regulation.