what is niacin b3
Niacin (also known as vitamin B3 or nicotinic acid) is an organic compound with the formula C 6H 5NO 2 and, depending on the definition used, one of the 20 to 80 essential human nutrients.iacin cannot be directly converted to nicotinamide, but both compounds are precursors of the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) in vivo. NAD converts to NADP by phosphorylation in the presence of the enzyme NAD+ kinase.