malnutrition
n. a state characterized by an unhealthy balance of carbohydrates, fats, proteins, vitamins, and minerals in the diet. Malnutrition may be due to excessive intake of certain food categories, as in obesity and hypervitaminosis (see vitamin A toxicity; vitamin D toxicity), or inadequate food intake. Dietary deficiencies play a role in many physical and psychological disorders. For example, nicotinic acid deficiency is marked by depression and other mental disturbances (see pellagra). Research suggests that mild nutritional deficiencies have little, if any, effect on intelligence but that moderate and (especially) severe deficiencies can result in intellectual deficits. See also kwashiorkor; marasmus; thiamine; vitamin deficiency.