Nicotinamide is a form of vitamin B3 that plays essential roles in cell physiology through facilitating NAD+ redox homeostasis and providing NAD+ as a substrate to a class of enzymes that catalyze non-redox reactions. Nicotinamide is an inhibitor of SIRT1, it has insulinotropic action, it can induce differentiation and maturation of human fetal pancreatic islet cells. Nicotinamide may represent a safe treatment for Alzheimer's disease and other tauopathies, and that phosphorylation of tau at Thr231 may regulate tau stability. NMN zwitterion is a nicotinamide mononucleotide. It has a role as a mouse metabolite and an Escherichia coli metabolite. It is a conjugate base of a NMN(+). It is a conjugate acid of a NMN(-).