Niacin (vitamin B3) can be obtained from niacinamide an amide of niacin that is typically well tolerated and not associated with causing a “flushing” reaction.  

Niacin occurs in the body as two metabolically active coenzymes NAD (nicotinamide adenine dinucleotide) and NADP (NAD phosphate). Niacin has pervasive roles in energy-related and biosynthetic metabolic processes. At least 200 enzymes depend on these niacin cofactors. The NAD-dependent enzymes are involved in mostly catabolic oxidative reactions that release energy from carbohydrate fat and protein whereas the NADP-dependent enzymes more commonly function in biosynthetic pathways of compounds such as fatty acids.