Fish oil benefits appear to have a protective effect against Alzheimer’s disease and memory loss. In a Dutch study of 815 healthy older people, those who consumed fish at least once a week were 60 percent less likely to develop Alzheimer’s than people who ate fish less frequently. These results held true even when other risk factors were ruled out the researchers found that those who ate fish two times a week slowed their mental decline by l3 percent per year eat one or two servings of fatty fish weekly, or buy a fish-oil supplement and take l gram per day. When taking fish oils Speciï¬cally for brain health, doctors recommend ï¬nding a supplement that contains at least 50 percent DHA as there is a strong link between DHA and brain function. Side effects of fish-oil supplements include gastrointestinal complaints, increased bleeding, and unpleasant breath.