A Canadian study involving 45,522 adults (30+) found that higher levels of physical activity, eating more fruits and vegetables, and having a BMI in the normal weight or overweight range were each associated with better cognitive function in both younger and older adults.

Specifically, for those who were normal weight or overweight (but not obese), eating more than 10 servings of fruit and vegetable daily was linked to better cognitive functioning. When moderate exercise was added, those eating less than five servings, reported better cognitive functioning.

Analysis also suggested that higher levels of physical activity may be in part responsible for the relationship between higher daily fruit and vegetable consumption and better cognitive performance.