Researchers at Harvard University conducted long-term studies on nearly 6,000 men and found that those who supplemented daily with 50mg of beta-carotene (which the body converts to vitamin A) had significantly better memory, cognitive function, and verbal recognition than those who took a placebo. Vitamin A may accomplish this by slowing the buildup of plaque in the brain.
It is recommended that 50mg of beta-carotene will provide this protective effect. By eating five or more servings of carotene-rich foods such as carrots, squash, broccoli, sweet potatoes, tomatoes, kale, collards, cantaloupe, peaches, or apricots you will fill your daily quotient. It is important to consume fat with this food to help facilitate absorption.