Essential coenzyme critical for energy metabolism, DNA repair, and sirtuin activation.
Serves as electron carrier in cellular respiration (NAD+/NADH cycling). Substrate for sirtuins (longevity proteins), PARP (DNA repair), and CD38. Declines ~50% between ages 40 and 60, potentially driving age-related decline.
NAD+ levels decline significantly with age. Research interest has exploded following discovery of its role in sirtuin activation — sirtuins are a family of proteins associated with longevity and stress resistance.
IV delivery produces the most rapid and complete repletion. SubQ administration is increasingly popular for convenience. Oral precursors (NMN, NR) are popular but bioavailability to specific tissues is debated.