Its opposite number is L-tyrosine, required for norepinephrine and dopamine, two neurotransmitters that increase alertness. Meat, poultry, and tofu provide L-tyrosine. Too Minerals such as calcium, magnesium and potassium also help the brain to function properly. All dairy products contain calcium, and so do many of the leafy greens. Magnesium, which both relieves stress and balances calcium absorption, can be obtained from peanut butter or tofu.
Potassium is found in bananas and potatoes.
Iron is probably the best known nutritive mineral. Without iron, the body cannot properly manufacture hemoglobin to carry oxygen into the brain. An iron deficiency can result in problems with memory, concentration, and reasoning. Raisins, red meat, tofu, and squash seeds are good sources of iron. If you choose to eat red meat however, buy naturally raised products.