It's more than likely that the NAD+ supplement craze has already crossed your path. NAD+ (short for nicotinamide adenine dinucleotide) is a coenzyme that your body makes naturally—it contributes to energy production and immune function, among other things. Nicotinamide adenine dinucleotide or NAD is a coenzyme found in all living cells. 3d illustration Illustration: Ollaweila/Getty ImagesAs we said, NAD+ is short for nicotinamide adenine dinucleotide. Your body produces and replenishes NAD+ by converting precursor molecules into NAD+ inside cells, using multiple metabolic pathways fueled by nutrients from foods like whole grains, lean meats, and legumes.