NAD-NAD is the abbreviation for Nicotinamide adenine denucleotide. We discussed niacin in the vitamin section. Niacin is a vitamin required as a component of the coenzymes NAD⁺ and NADP⁺ . These coenzymes¹ function in oxidation-reduction reactions. Oxidation- reduction reactions are simply reactions which involve the transfer of electrons. Reduction is the gain of an electron by an atom or a substance and oxidation is the loss of an electon. Electrons are part of each atom and have a "negative charge". Therefore, if an atom has lost one of its electrons, it has a "net" positive charge. We saw another example of this with chloride portion of sodium chloride. We can see that NAD⁺ and NADP⁺ have a net positive charge, indicated by the "plus sign" (⁺).

¹ NAD is cofactor form (of niacin), acting as a coenzyme.