Niacin

Niacin, (which is also known as nicotinic acid or vitamin B3), is a water-soluble vitamin. Nicotinamide is the metabolite of niacin and used by the body to form the coenzymes nicotinamide adenine dinucleotide phosphate (NADP) and nicotinamide adenine dinucleotide (NAD). None of the forms are related to the nicotine found in tobacco, although their names are similar.

Living organisms derive a great portion of their energy from oxidation-reduction (redox) reactions, transfering electrons. About 200 enzymes require the niacin coenzymes, NAD and NADP, to accept or donate electrons in redox reactions. NAD functions most often in energy producing reactions involving the catabolism of carbohydrates, fats, proteins, and alcohol. NADP functions more often in anabolic reactions, such as in the synthesis of all macromolecules, including fatty acids and cholesterol.