2. Fish
Omega-3 oils found in cold-water fish such as salmon contain fatty acids essential for a healthy brain and also for fighting depression. A study from Louisiana State University showed that eating fish helps protect the brain from problems associated with Alzheimer's disease, and a study from Australia's Aberdeen University found that fish oil slows the aging process while helping the brain work faster. Many experts suggest eating two portions of fish each week or taking a 1,000 mg fish oil supplement three times a day.