Condition resulting from inadequate diet or from inability to absorb or metabolize nutrients. Food intake may be insufficient to supply calories or protein (seekwashiorkor) or deficient in one or more essential vitamins or minerals. The latter case can lead to specific nutritional deficiency diseases (including beriberi, pellagra, rickets, and scurvy). Metabolic defects, especially of the digestive system, liver, kidneys, or red blood cells, prevent proper digestion, absorption, and metabolism of nutrients. See alsonutrition.