Populations that eat fish regularly live longer and have less chronic disease than populations that do not. Whether this is because fish displaces meat or because it has positive attributes of its own is not clear. Certainly, fish provides high-quality protein without the saturated fat present in meat and poultry. Recent research suggests that supplementing the diet with omega-3 fatty acids not only can reduce these risks but can also help treat depression, bipolar disorder, autism, and attention deficit hyperactivity disorder. Fish is, indeed, a brain food.