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Nicotinic acid (niacin, another term for nicotinic acid, was introduced to avoid confusion with the alkaloid nicotine) is converted in the body to two important coenzymes in carbohydrate metabolism: nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate. Dietary deficiency of nicotinic acid produces pellagra (from the Italian pelle agra, meaning rough skin). Pellagra classically occurs in populations who consume primarily corn. Corn lacks nicotinic acid as well as tryptophan, a precursor that can be converted in the body to nicotinic acid. In underdeveloped countries, pellagra is still a common health problem. Even in the United States, pellagra was endemic until approximately 1940 in the South and in alcoholic populations. It has now largely disappeared, credited to the widespread consumption of bread enriched with niacin.

Clinical Features

Pellagra affects three organ systems in the body: the GI tract, skin, and nervous …