From WebMD

• For brain and heart health, eat two servings of fish weekly
• Enjoy up to an ounce a day of nuts and dark chocolate to provide all the benefits you need without excess calories, fat, or sugar.
• Eating a diet high in whole grains and fruits like avocados can reduce the risk of cardiovascular disease and lower bad cholesterol. (Though avocados have fat, it's the good-for-you, monounsaturated fat that contributes to healthy blood flow.)
• Research shows that blueberries help protect the brain from oxidative stress and may reduce the effects of age-related conditions such as Alzheimer's disease or dementia. Diets rich in blueberries significantly improve both learning capacity and motor skills.
• Get Ready for a Big Day:Want to power up your ability to concentrate? Start with a meal of 100% fruit juice, a whole grain bagel with salmon, and a cup of coffee. In addition to eating a well-balanced meal, experts also advise:
  • Get a good night's sleep.
  • Stay hydrated.
  • Exercise to help sharpen thinking.
  • Meditate to clear thinking and relax.
• Eating breakfast may improve short-term memory and attention. Students who eat breakfast tend to perform significantly better than those who don’t. (Include high-fiber whole grains, dairy, and fruits. Just don't overeat)