Niacin, also known as nicotinic acid, is a water soluble vitamin derived from the amino acid tryptophan. Nicotinamide is its amide form. It is an essential component of the coenzymes NAD and NADP, concerned with energy releasing reactions.
Sources include yeast, meats, liver, fish, whole-grain products, peas, beans, instant coffee, cheese and nuts. Milk and eggs have minimal niacin content but contain tryptophan. Metabolically, niacin can be produced from tryptophan in the presence of pyridoxine. Typically, half the physiological requirements of niacin are obtained directly whereas the other half is obtained from tryptophan.
In lipid metabolism, it inhibits production of cholesterol and assists in fat breakdown.
Deficiency results in pellagra.
Last reviewed 01/2018