Nicotinamide adenine dinucleotide (NDA+) is a coenzyme found in all living cells. It serves both as a critical co-enzyme for enzymes that fuel oxidation-reduction reactions, carrying electrons from one reaction to another, and as a co-substrate for other enzymes such as the sirtuins and polymerases. Cellular NAD+ concentrations decrease during aging, and modulation of NDA+ usage and production can prolong both health and life span.