NAD+ (nicotinamide adenine dinucleotide) is a naturally occurring coenzyme present in every living cell, where it serves as a central electron carrier in redox reactions and as a substrate for sirtuins, PARPs and CD38.1 Tissue NAD+ levels have been reported to decline with age across multiple species, including humans, which has driven interest in NAD+ as a longevity target.2 An important caveat: most controlled human data come from oral precursors such as nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR) rather than from NAD+ itself, and while these reliably raise blood or muscle NAD+, they have not consistently produced clinically meaningful functional changes.3 NAD+ is a research compound; it is not an approved drug or supplement for any use.
Sequence & identity
Dinucleotide of nicotinamide mononucleotide and adenosine monophosphate joined by a pyrophosphate bridge; identity per PubChem CID 5892 (InChIKey BAWFJGJZGIEFAR-NNYOXOHSSA-N).1
Mechanisms studied
NAD+ cycles between its oxidised (NAD+) and reduced (NADH) forms to shuttle electrons through glycolysis, the tricarboxylic acid cycle and oxidative phosphorylation, making it indispensable for ATP generation.1 Beyond redox chemistry, NAD+ is consumed as a co-substrate by sirtuin deacylases, poly(ADP-ribose) polymerases (PARPs) and the cyclic-ADP-ribose synthase CD38, linking cellular NAD+ availability to gene regulation, DNA-damage responses and signalling.1 Because these consuming enzymes and synthetic flux differ by tissue, researchers describe NAD+ homeostasis as a balance between synthesis and degradation that shifts with age and metabolic state.2
Dosing in the research literature
The figures below summarise regimens as reported in published research — they are not recommendations or directions for use.
| Source / model | Regimen reported | Notes |
|---|---|---|
| Igarashi et al., NPJ Aging 2022 (NMN precursor) | 250 mg oral NMN per day for 12 weeks in healthy older men | Reported as well tolerated; elevated blood NMN and NAD+ versus placebo, with nominally significant gains in gait speed (P=0.033) and left grip strength (P=0.019). Not a study of NAD+ itself.4 |
| Elhassan et al., Cell Reports 2019 (NR precursor) | 1 g oral NR per day for 21 days, randomised double-blind crossover, 12 men aged 70–80 | Augmented the skeletal-muscle NAD+ metabolome and lowered circulating IL-6, IL-5, IL-2 and TNF-α; mitochondrial bioenergetics were unchanged.5 |
| Yoshino M. et al., Science 2021 (NMN precursor) | 250 mg oral NMN per day for 10 weeks in prediabetic postmenopausal women | Increased insulin-stimulated muscle glucose disposal and muscle insulin signalling; no change in hepatic insulin response or fasting glucose.6 |
Effects observed in research
In controlled human trials of NAD+ precursors, supplementation consistently raised measured NAD+ levels in blood or skeletal muscle.45 Reported downstream observations have been more variable: researchers noted modest gains in some muscle-performance measures and improved muscle insulin sensitivity in a prediabetic cohort, alongside reduced inflammatory cytokines in aged muscle.456 Several investigators caution that raising NAD+ has not yet been shown to translate into consistent, clinically meaningful functional benefit, and that larger standardised trials are needed.3
Strength of evidence
Grade B. The biochemistry of NAD+ as a redox coenzyme is firmly established.1 Human outcome evidence, however, derives mainly from small, short randomised trials of the precursors NMN and NR rather than from NAD+ itself; these show reliable NAD+ elevation but inconsistent functional endpoints.3456 Direct oral bioavailability of intact NAD+ in humans has limited published characterisation. Findings should be read as preliminary.
Reconstitution & storage
Reconstitute with bacteriostatic water for laboratory handling. Store lyophilised material frozen and reconstituted material refrigerated. Use Peptigo’s reconstitution calculator and storage cheat sheet for working figures.
References
- PubChem Compound Summary for CID 5892, NAD (nicotinamide adenine dinucleotide). National Center for Biotechnology Information. https://pubchem.ncbi.nlm.nih.gov/compound/5892 (accessed 2026-06-03).
- Covarrubias AJ, Perrone R, Grozio A, Verdin E. NAD+ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology. 2021;22(2):119-141.
- Cantó C, Menzies KJ, Auwerx J. NAD+ metabolism and the control of energy homeostasis: a balancing act between mitochondria and the nucleus. Cell Metabolism. 2015;22(1):31-53. PMID 26118927.
- Igarashi M, et al. Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men. NPJ Aging. 2022;8(1):5.
- Elhassan YS, et al. Nicotinamide riboside augments the aged human skeletal muscle NAD+ metabolome and induces transcriptomic and anti-inflammatory signatures. Cell Reports. 2019;28(7):1717-1728.
- Yoshino M, Yoshino J, Kayser BD, et al. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science. 2021;372(6547):1224-1229. DOI 10.1126/science.abe9985.