The major function of niacin is in the coenzyme forms of nicotinamide, NAD and NADP. Enzymes containing NAD and NADP are important links in a series of reactions associated with carbohydrate, protein and lipid metabolism.
Chemically, niacin is one of the simplest vitamins, having the empirical formula C6H3O2N.
Niacin is widely distributed in feedstuffs of both plant and animal origin. Animal and fish by-products, distiller's grains and yeast, various distillation and fermentation solubles and certain oilseed meals are good sources. The niacin in cereal grains and their by-products is in a bound form, which is largely unavailable at least to monogastric animals.
