NAD+ — Research Notes
One of the most-studied molecules in longevity science. NAD+ is a coenzyme rather than a peptide, but is widely tracked alongside research peptides for its role in aging, cellular repair, and metabolic function.
What it is
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every living cell. It functions as an essential electron carrier in metabolic reactions and as a required substrate for a class of enzymes called sirtuins (which regulate gene expression and DNA repair) and PARPs (poly ADP-ribose polymerases, involved in DNA damage response). NAD+ is not a peptide, but it is commonly tracked alongside research peptides by individuals researching longevity and cellular aging.
A foundational observation in aging research is that NAD+ levels decline with age in multiple tissues.[1] This has driven significant interest in approaches that restore or maintain NAD+ levels, primarily through oral supplementation with precursors: nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR). Injectable NAD+ bypasses the gut conversion step required for oral precursors and is used in some research and clinical contexts where rapid systemic elevation is studied.
What researchers study it for
- Aging and age-related NAD+ decline NAD+ concentrations decline substantially with age in metabolic tissues including liver, muscle, and brain; a comprehensive 2015 review by Verdin established the mechanistic connections between this decline and hallmarks of aging such as mitochondrial dysfunction, increased oxidative stress, and impaired DNA repair.[1]
- Sirtuin activation and DNA repair Sirtuins (SIRT1–SIRT7) are NAD+-dependent deacylases that regulate transcription, metabolism, and genomic stability; their activity is directly limited by NAD+ availability, making NAD+ repletion a research strategy for supporting sirtuin-mediated stress resistance and DNA damage response in aging cells.[1]
- NR supplementation: tolerability and blood NAD+ elevation A 2018 randomized, double-blind, crossover clinical trial found that oral nicotinamide riboside supplementation was well-tolerated and significantly elevated whole-blood NAD+ levels in healthy middle-aged and older adults, providing the first controlled human evidence that an oral NAD+ precursor could reliably increase systemic NAD+ concentrations.[2]
- NMN supplementation: muscle function and physical performance A 2022 randomized, double-blind, placebo-controlled trial by Igarashi et al. found that 250 mg/day oral NMN for 12 weeks significantly increased whole-blood NAD+ and NAD+-related metabolites in healthy older men, with nominally significant improvements in gait speed and grip strength, though the researchers noted these functional gains would benefit from larger confirmatory studies.[3]
- Arterial stiffness and cardiovascular markers A 2023 randomized controlled trial examined 12 weeks of NMN supplementation (125 mg twice daily) in healthy middle-aged participants, finding a trend toward reduced arterial stiffness as measured by pulse wave velocity in the NMN group, though the difference between groups did not reach statistical significance; NAD+ and nicotinamide levels in serum were significantly elevated.[4]
- Cognitive and neurological research NAD+ decline in the brain has been studied in relation to neurodegenerative conditions; preclinical work has examined NAD+ repletion as a strategy for reducing markers of neurodegeneration, with particular interest in Alzheimer's and Parkinson's disease models, though human trial data in this area remains limited.[5]
Research context
The evidence base for NAD+ and its precursors is substantially larger and more human-focused than for most research peptides. The NR and NMN clinical trials conducted between 2018 and 2024 consistently demonstrate that oral precursor supplementation is well-tolerated and reliably elevates blood NAD+ levels in humans.[2][3] What remains less clear is whether this biochemical change translates into meaningful functional benefits. Effect sizes in published trials have generally been modest, and the field is still working to establish which outcomes matter most in which populations.
Injectable NAD+ is used in some clinical and research settings and produces more rapid plasma elevation than oral precursors. It is less studied in controlled human trials than NMN or NR. The longevity and anti-aging applications that have attracted the most public attention are based primarily on preclinical evidence from model organisms and mechanistic reasoning from the sirtuin biology; direct evidence that raising NAD+ levels extends human lifespan or meaningfully slows aging is not yet available.[6]
Typical research parameters
| Parameter | Typical range / notes |
|---|---|
| Research forms | Injectable NAD+ (lyophilized powder or solution); oral NMN (powder or capsule); oral NR (capsule); all three are tracked on PPL |
| Common vial sizes (injectable) | 500 mg vials most common; also available in 250 mg and 1,000 mg |
| Supplied as | Injectable: lyophilized powder or pre-mixed solution. Oral precursors: capsule or bulk powder |
| Storage | Injectable: refrigerate after reconstitution; protect from light; lyophilized stable at room temperature short-term. Oral precursors: room temperature, sealed |
| Stability | Injectable NAD+ is relatively unstable in solution; use within 24–48 hours of reconstitution. Lyophilized: 12–24 months |
| Administration studied | Intravenous and subcutaneous injection (injectable NAD+); oral supplementation (NMN, NR in human clinical trials) |
References
- [1] Verdin E. NAD+ in aging, metabolism, and neurodegeneration. Science. 2015;350(6265):1208-13. PubMed ↗
- [2] Trammell SA et al. Nicotinamide riboside is uniquely and orally bioavailable in healthy humans. Nat Commun. 2016;7:12948. / Martens CR et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nat Commun. 2018;9:1286. PubMed ↗
- [3] 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;8:5. PubMed ↗
- [4] Katayoshi T et al. Nicotinamide adenine dinucleotide metabolism and arterial stiffness after long-term nicotinamide mononucleotide supplementation: a randomized, double-blind, placebo-controlled trial. Sci Rep. 2023;13:2786. PubMed ↗
- [5] Lautrup S et al. NAD+ in brain aging and neurodegenerative disorders. Cell Metab. 2019;30(4):630-55. PubMed ↗
- [6] Yoshino J et al. NAD+ intermediates: the biology and therapeutic potential of NMN and NR. Cell Metab. 2018;27(3):513-28. PubMed ↗