Pathogenesis
The deficient molecule, niacin (vitamin B3), refers to pyridine compounds, namely nicotinic acid and nicotinamide.
It is a water-soluble vitamin which is readily converted to nicotinamide-adenine-dinucleotide (NAD) and its phosphate (NADP) that are involved in metabolic reactions as hydrogen ion donors or acceptors. NAD is involved in glycolysis and catabolism of protein and alcohol, whereas NADP acts as a hydrogen acceptor in the electron transport chain and functions in cholesterol and fatty acid synthesis.
These two pyrimidine compounds are essential for oxidative phosphorylation and DNA regulation.2, 7, 8 Deficiency of these coenzymes can inhibit the repair of cell damage and affect tissues with high cellular turnover such as the brain, gastrointestinal tract and skin.