Encyclopedia

NAD+ (nicotinamide adenine dinucleotide) is an essential coenzyme found in every living cell, required for cellular energy (ATP) production, DNA repair, and as a substrate for sirtuin enzymes involved in aging biology. It is not a peptide (it is a dinucleotide) but is widely marketed alongside peptides as an IV or subcutaneous infusion for energy, cognition, and anti-aging. It is not FDA-approved as a drug for any of these marketed indications; controlled human trial evidence for IV/injectable NAD+ specifically is limited.

NAD+ is composed of two nucleotides joined by a pyrophosphate bond: one bearing adenine, the other bearing nicotinamide. It exists in oxidized (NAD+) and reduced (NADH) forms and cycles between them as a central electron carrier in cellular respiration, making it essential for mitochondrial ATP production. Beyond energy metabolism, NAD+ is a required substrate for sirtuins (NAD-dependent deacetylases implicated in aging and metabolic regulation), PARP enzymes involved in DNA repair, and CD38, which consumes NAD+ and whose activity increases with age -- a proposed mechanism for the age-related decline in tissue NAD+ levels that underlies much of the 'NAD+ boosting' longevity marketing. Unlike its precursors nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN), which are sold as oral supplements with a larger human trial base, direct IV or subcutaneous NAD+ administration has a much thinner controlled-trial evidence base; most published human data are small, short-term tolerability/pilot studies rather than large randomized efficacy trials for any of the commercially marketed benefits (energy, cognition, hangover recovery, anti-aging).

Mechanism of Action

Functions as a coenzyme carrying electrons in oxidation-reduction reactions central to mitochondrial ATP synthesis (glycolysis, the citric acid cycle, oxidative phosphorylation). Serves as an obligate substrate for sirtuin deacetylases, PARP DNA-repair enzymes, and NAD-glycohydrolases (e.g., CD38), linking cellular NAD+ availability to energy metabolism, genomic stability, and proposed aging pathways.