Eating a diet rich in fruits and vegetables, moderate in nuts, fish and alcohol and low in meat and full-fat dairy is associated with better cognitive performance in middle age. The study involved 2,621 people who were an average age of 25 at the start and were then followed for 30 years.

See the source article by following the link below:
Eating a diet rich in fruits and vegetables, moderate in nuts, fish and alcohol and low in meat and full-fat dairy is associated with better cognitive performance in middle age. The study involved 2,621 people who were an average age of 25 at the start and were then followed for 30 years.