NAD is the abbreviation used for Nicotinamide Adenine Dinucleotide, the biologically active coenzyme form of vitamin B3 (Niacinamide). NAD is the oxidized form of coenzyme B3 that acts as a hydrogen (H) acceptor, while NAD(H) (known as NADH) is the reduced form that donates hydrogen as part of the Krebs’ Citric Acid Cycle (KCAC) and Electron Transport Side Chain (ETSC). NADH is a complex molecule comprised of vitamin B3, ribose, a mineral compound called a phosphate group and another compound called adenine nucleotide that can be made in the liver and other cells.
NAD and NADH can each be converted back-and-forth into the other form many times during the body’s energy production cycles. They are both involved in transferring electron pairs (energy “sparks”) during energy transfer reactions within the cell. Chemical energy in the form of ATP (Adenosine Tri-Phosphate) is produced in this cycle.