Omega-3 fatty acids are a form of polyunsaturated fat that the body derives from food. Omega-3s (and omega-6s) are known as essential fatty acids (EFAs) because the body cannot make these fatty acids on its own so omega-3s must be obtained from food. These different types of fatty acids can be obtained in foods such as cold-water fish including tuna, salmon, and mackerel. Other important omega 3 fatty acids are found in dark green leafy vegetables, flaxseed oils, walnuts, chia seeds, and certain vegetable oils. Omega-3 fatty acids have been found to be beneficial for the heart.