Leonardo da Vinci, Mohandas Gandhi, George Bernard Shaw, and the Nobel Prize-winning mathematician Norbert Wiener were all vegetarians. Their genius was powered by plants.

If you want to keep your brain sharp and avoid dementia, yours should be too, according to researchers who studied the MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) diet.

The MIND diet calls for eating at least three servings of whole grains and at least one dark green leafy salad and one other vegetable daily, along with a glass of wine. Beans and legumes should be eaten at least every other day; poultry and berries, at least twice a week; fish once a week; and for snacks, go nuts (an ounce a day).

The diet guidelines also say it's equally important to avoid butter, cheese, fried or fast food, and red meat. The diet allows less than a serving a week for them. (We say avoid them altogether.) 

The researchers tracked almost 1,000 people ages 58 to 98 for four and a half years and found that reliably sticking to the MIND diet reduced participants' risk of developing Alzheimer's disease by 53%. It fell by 35% if they followed guidelines only moderately well. 

The MIND diet reduces oxidative stress and inflammation, and the phytochemicals it contains may help prevent the buildup of beta-amyloid plaques that are associated with Alzheimer's.