Re: What is the B vitamin number of Niacin

Niacin - either nicotinic acid or nicotinamide (shown here) - is designated as Vitamin PP ("PP" stands for "Pelagra-Preventing"). Because of its inclusion in the B-complex group of vitamins, I have also seen it referred to as vitamin B₃; however, this name is not recognized by IUPAC or any scientific organization I could find - they all refer to it as vitamin PP. Niacin is used by cells to make the dinucleotide coenzymes NAD+ (Nicotinamide Adenosine Dinucleotide) and NADP+ (NAD-Phosphate), which are important for energy transfer and storage. The numbered B-complex vitamins are thiamine (vitamin B₁), riboflavin (vitamin B₂), pyridoxine (vitamin B₆), and cobalamin (vitamin B₁₂). The B-complex also includes biotin, folic acid, and pantothenic acid.