Omega-3s are polyunsaturated fatty acids found mainly in fatty fish and vegetable oils. Many food products claim to have Omega-3s, but not all Omega-3s are created equal. Other vegetarian sources of Omega-3 fatty acids, such as walnuts, flaxseed and vegetable oils, are actually sources of alpha-linolenic acid (ALA), not DHA. DHA is one of the omega-3 fatty acids. The body can make DHA from ALA but the process is inefficient.