nutritional disorders
Niacin Deficiency
Introduction
Dietaryniacindeficiency (causing pellagra) is uncommon in countries with low rates of food insecurity. Clinical manifestations include the three Ds: localized pigmented rash (dermatitis); gastroenteritis (diarrhea); and widespread neurologic deficits, including cognitive decline (dementia). Diagnosis is usually clinical, and dietary supplementation (oral or, if needed, intramuscular ) is usually successful. Niacin(nicotinic acid, nicotinamide) derivatives include nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are coenzymes in oxidation-reduction reactions. They are vital in cell metabolism. Dietary sources ofniacininclude liver, red meat, fish, poultry, legumes, and whole-grain or enriched cereals and breads. Because dietarytryptophancan be metabolized toniacin, foods rich intryptophan(eg, dairy products) can compensate for inadequate dietaryniacin. (See also Overview of Vitamins .) 