Source Naturals Niacinamide, also known as vitamin B-3, functions in over 50 metabolic reactions, most of which are enzymatic. Niacinamide bioactive forms - NAD+, NADH, NADP, and NADPH - play important roles as catalysts in the energy production process in the cells, the breakdown of proteins and fatty acids, the synthesis of fatty acids, and the formation of steroid hormones and red blood cells.