NAD+

Nicotinamide adenine dinucleotide (NAD+) is a coenzyme present in all living cells that serves as an electron carrier in metabolic redox reactions and as a substrate for enzymes including sirtuins, PARP (poly ADP-ribose polymerase), and cyclic ADP-ribose synthases. NAD+ levels decline approximately 50 percent between young adulthood and midlife, a reduction associated with mitochondrial dysfunction, impaired DNA repair, metabolic disease, and accelerated aging. Direct NAD+ infusions, typically administered intravenously, bypass the need for precursor conversion and acutely raise cellular NAD+ levels. Clinical interest has grown substantially, with NAD+ IV therapy being used in addiction recovery programs, brain health optimization, and age-related decline. While oral precursors such as NMN and NR are more convenient, IV NAD+ provides more immediate and potent NAD+ repletion. The breadth of NAD+-dependent biological processes makes it one of the most compelling targets in longevity medicine.