NAD+ (Nicotinamide Adenine Dinucleotide)

NAD+ (nicotinamide adenine dinucleotide) is not technically a peptide — it is a dinucleotide coenzyme composed of two nucleotides joined by phosphate groups. It exists in two forms: NAD+ (oxidized, electron acceptor) and NADH (reduced, electron donor). The NAD+/NADH ratio is a critical determinant of cellular redox state, affecting over 400 enzymatic reactions.

NAD+ serves as a co-substrate for three major enzyme families: (1) Sirtuins (SIRT1–7), NAD+-dependent deacetylases that regulate metabolism, DNA repair, and longevity pathways; (2) PARPs (poly-ADP-ribose polymerases), DNA repair enzymes that consume NAD+ at damage sites; (3) CD38 and CD157, NAD+ glycohydrolases on immune cells. NAD+ levels decline approximately 40–50% between ages 40 and 60, driven by increased CD38 activity and PARP activation from accumulated DNA damage.

Unlike oral NAD+ precursors (NMN, NR) which depend on the rate-limiting NAMPT enzyme for conversion, direct NAD+ administration bypasses the salvage pathway entirely, delivering the coenzyme in its active form. This makes it a valuable research tool for studying NAD+-dependent processes independent of precursor availability.

NAD+ was first discovered in 1906 by Harden and Young as a "co-ferment" required for yeast fermentation. Its structure was elucidated in the 1930s by Warburg and von Euler. The modern longevity-focused research era began in the early 2000s with the discovery that NAD+ is the rate-limiting substrate for sirtuins — linking the coenzyme to the same pathways targeted by caloric restriction and resveratrol.

David Sinclair's lab at Harvard has been central to NAD+ aging research, demonstrating that NAD+ repletion reverses age-associated mitochondrial dysfunction, improves stem cell function, and extends healthspan in rodent models. The field has attracted significant investment, with NAD+ precursor supplements (NMN, NR) generating over $500M annually as of 2026, though direct NAD+ administration research remains the gold standard for mechanistic studies.

Store lyophilized NAD+ at -20°C in a tightly sealed, desiccated container. NAD+ is hygroscopic — exposure to atmospheric moisture can cause hydrolysis of the pyrophosphate bond. Stability under optimal conditions exceeds 18 months.

Reconstituted NAD+ should be stored at 2–8°C and used within 7 days — shorter than peptide solutions due to the compound's susceptibility to enzymatic degradation. Some research protocols use sterile saline (0.9% NaCl) rather than BAC water for reconstitution, citing reduced irritation potential with the larger injection volumes typical of NAD+ research. The reconstituted solution is slightly acidic (pH ~4–5); this is normal and expected.