A person's food intake affects mood, behavior, and brain function Deficiencies or excesses of certain vitamins or minerals can damage nerves in the brain, causing changes in memory, limiting problem-solving ability, and impairing brain function.

NUTRIENT	MENTAL DISORDER RESULTING FROM DEFIENCY
Energy intake	lower fluency and problem solving ability, lack of energy and motivation
Carbohydrates	Excess insulin produces higher serotonin which has a sedating effect on the brain, promoting sleepiness.
Proteins	Results in fall in amino acid level which results in mood variation like depression or aggression.
Fats	High fat level results in clogging of arteries resulting in decreased blood flow to the brain which can cause stroke.
Alcohol	Excess alcohol intake can affect mood
Vitamins	Alcoholism is often associated with Thiamin deficiency. Folic acid deficiency increases risk of stroke. Niacin deficiency produces many mental symptoms such as irritability, headaches, loss of memory, inability to sleep, and emotional instability. Vitamin B-6(pyridoxine) deficiency leads to fatigue, nervousness, irritability, depression, insomnia, dizziness, and nerve changes. Vitamin A deficiency causes fatigue, irritability, and loss of appetite.
Minerals	Iron deficiency eventually leads to anemia which can cause fatigue and impair mental functioning. Magnesium deficiency can cause restlessness, nervousness, muscular twitching, and unsteadiness Deficiency of copper causes anemia, with inadequate oxygen delivery to the brain and other organs. Zinc deficiency can cause neurological impairment, influencing appetite, taste, smell, and vision. Selenium toxicity causes nervous system changes, fatigue, and irritability.