Vitamin B3, also known as niacin, or vitamin PP, molecular formula: C6H5NO2, heat resistant, can sublimate. It is one of the 13 essential vitamins, is a water-soluble vitamin, belongs to the vitamin B group. Niacin is converted into nicotinamide in the body, which is a component of coenzyme ⅰ and coenzyme ⅱ and is involved in lipid metabolism, oxidative process of tissue respiration and anaerobic decomposition of sugars. Niacin is mainly found in food as a coenzyme and is absorbed from the stomach and small intestine after digestion. After absorption in the form of niacin through the portal vein into the liver. Much of the excess niacin is methylated out of the urine. Niacin nicotinic acid It is one of the B vitamin complexes that acts as an anti-pellagra factor. Also known in the United States as Niacin. Nicotinic acid has been known chemically since 1867, but as a vitamin was formulated by C. A. Elvehjem (1937). Yeast, liver, animal and bird meat, leaf vegetables contain a lot of niacin. In animal fungi, it can be formed from tryptophan via canine urine-amino acid 3-hydroxy-2-aminobenzoic acid. Deficiency does not occur as long as protein rich in tryptophan is consumed. Every 60 milligrams of tryptophan is said to be equal to 1 milligram of niacin. It is formed by condensation of aspartic acid with C3 (glycerol metabolite) in plants and bacteria, and is changed into nicotinamide in the human body or becomes a constituent of NAD and NADP by nicotinic acid.