Niacinamide is the form of niacin that circulates in the bloodstream. Niacinamide is utilized by all body tissues to synthesize nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), the active forms of niacin. NAD and NADP are essential for over 200 enzymes and function as a hydrogen donor or electron acceptor (important for the synthesis of energy-ATP). NAD is also involved in the activation of folate and regeneration of reduced glutathione. Niacinamide and niacin are the two forms of Vitamin B3. Niacinamide does not cause flushing or skin irritation.