Compound reference
NAD+
Also known as Nicotinamide adenine dinucleotide, NAD
NAD+ is a central redox coenzyme whose levels fall with age, making it a flagship longevity target via precursors (NMN, NR) and IV drips. The biology is real and precursors reliably raise NAD+ in people — but proven human healthspan benefit is lacking, and IV NAD+ is essentially unevidenced.
- CAS
- 53-84-9
- Formula
- C₂₁H₂₇N₇O₁₄P₂
- Molar mass
- ≈663.4 g/mol
Endogenous coenzyme; not an FDA-approved drug. Precursor and IV anti-aging use is not proven.
Mode of action
To be clear at the outset, NAD+ (nicotinamide adenine dinucleotide) is not a peptide and not a drug — it is one of the most fundamental coenzymes in biology, included here because it anchors a huge longevity-supplement market that sits alongside the research-peptide world. NAD+ plays two roles: it is the central redox carrier of energy metabolism (cycling between NAD+ and NADH), and it is a consumed substrate for important signaling enzymes — the sirtuins, the PARP DNA-repair enzymes, and CD38. Those consumer enzymes mean cells continually spend NAD+, so supply matters.
The longevity premise rests on one well-established observation: tissue and cellular NAD+ levels decline with age. The strategy is therefore to "boost" NAD+. Crucially, you cannot do this effectively by ingesting NAD+ itself — it is poorly absorbed intact — so the field relies on precursors the body converts into NAD+, principally nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR), as well as on intravenous NAD+ infusions whose ability to actually raise intracellular NAD+ is pharmacologically doubtful.
Main intended effect
To restore the age-related decline in NAD+ and thereby improve metabolic health, cellular energy, and "healthspan."
Areas of interest
The dominant framing is longevity and healthy aging. Specific interests include metabolic health (insulin sensitivity, fatty liver), muscle and exercise performance, and neurological/cognitive aging. Commercially, the action is in oral precursors (NMN and NR supplements) and in intravenous NAD+ infusions offered by wellness clinics — the latter also marketed, without good evidence, for addiction recovery and general "anti-aging."
Evidence for intended effects
The honest reading separates three things that are often blurred together. First, the biology is real and important: NAD+ decline with age is well documented and mechanistically central, and in mice, raising NAD+ with precursors improves a range of metabolic and aging measures. Second, the pharmacology works: human trials confirm that oral NR and NMN reliably raise the NAD+ metabolome — NR roughly doubled blood NAD+ in healthy older adults, for example. That much is established.
Third — and this is where the marketing outruns the science — the human health outcomes are modest, mixed, or absent. The most-cited positive human result (NMN improving muscle insulin sensitivity in prediabetic women) is a single, contested study, criticized for a baseline imbalance between groups. Meta-analyses tell the sobering story: pooled NMN trials show no significant benefit on glucose or lipid metabolism, and reviews of NMN/NR find no convincing benefit for muscle mass or function. A 2025 clinical-evidence appraisal frames the core problem plainly — precursors raise NAD+, but that has not yet translated into demonstrated healthspan benefit in people, and the mouse-to-human gap is wide. Intravenous NAD+, the most aggressive version, has essentially no rigorous efficacy evidence at all.
| Strand | What exists | Tier |
|---|---|---|
| NAD+ decline with age / biology | Strong, across organisms incl. humans | Established |
| Precursors raise NAD+ in humans | NR and NMN RCTs confirm | Established (pharmacology) |
| Human health outcomes | Single contested positive (NMN); meta-analyses largely null | Weak / mixed |
| IV NAD+ | No rigorous efficacy evidence | Unevidenced |
Studied amounts (literature dosing context)
Human precursor trials used oral NMN at roughly 250–1000 mg/day and NR at roughly 250–1000 mg/day over weeks to months. Intravenous NAD+ clinics use infusions on the order of hundreds of milligrams to a gram per session, with no standardized, evidence-based regimen. NAD+ taken orally as the intact molecule is poorly bioavailable. These are trial and market figures, not dosing guidance.
Safety and regulatory status
The precursors have a reassuring short-term tolerability record: NR and NMN were well tolerated in controlled trials. NR (as the branded Niagen) is marketed as a legal dietary supplement in the United States. NMN's status has been turbulent — the FDA excluded it from the supplement definition in 2022 (because it had been investigated as a drug), then reversed that position in 2025, confirming it as a lawful supplement. Intravenous NAD+ is not an FDA-approved treatment for any indication and is administered through compounding and wellness clinics. One mechanistic caution deserves mention: because NAD+ also fuels the metabolism of cancer cells, indefinitely boosting it is theoretically double-edged, a question not resolved by current human data. It is mechanistically adjacent to 5-Amino-1MQ, which aims to raise NAD+ indirectly by inhibiting the NAD+-consuming enzyme NNMT.
Sources
NAD+ metabolism and its roles in cellular processes during ageing
Authoritative review (Covarrubias and colleagues, Nature Reviews Molecular Cell Biology 2021) of NAD+ biology and its decline with age. NAD+ is both a redox coenzyme central to energy metabolism and a consumed substrate for non-redox enzymes including the sirtuins, PARPs, and CD38. The review documents that tissue and cellular NAD+ levels fall with age across organisms including humans, links this decline to aging-associated conditions (metabolic disease, cognitive decline, sarcopenia, frailty, cancer), and surveys NAD+-boosting strategies. It is the standard reference for the rationale behind NAD+ restoration, while making clear that the causal and translational questions remain open.
Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults
Randomized, double-blind, placebo-controlled crossover trial (Martens and colleagues, Nature Communications 2018) of the NAD+ precursor nicotinamide riboside (NR) in healthy middle-aged and older adults. Chronic NR was well tolerated and effectively raised the NAD+ metabolome (roughly doubling blood NAD+), establishing that an oral precursor can increase NAD+ in humans. Functional effects were only preliminary — a suggestion of reduced blood pressure and arterial stiffness in some participants — and the authors called for larger trials to test clinical benefit. The study confirms the pharmacology (NAD+ rises) more than any health outcome.
Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women
Randomized, double-blind, placebo-controlled trial (Yoshino and colleagues, Science 2021) of 250 mg/day oral nicotinamide mononucleotide (NMN) for 10 weeks in postmenopausal women with prediabetes who were overweight or obese. NMN raised the NAD+ metabolome and improved skeletal-muscle insulin sensitivity and insulin signaling. The result is frequently cited as the first human metabolic benefit of an NAD+ precursor, but it is contested — a published comment noted a baseline imbalance between groups (notably higher liver fat in the placebo arm), which complicates interpretation. A positive but disputed single signal rather than settled evidence.
Efficacy of oral nicotinamide mononucleotide supplementation on glucose and lipid metabolism for adults: a systematic review with meta-analysis of randomized controlled trials
Systematic review and meta-analysis (Critical Reviews in Food Science and Nutrition 2024) pooling randomized controlled trials of oral NMN supplementation (about 250-2000 mg/day over 2-12 weeks) for metabolic outcomes in adults. Despite NMN's well-documented ability to raise NAD+, the meta-analysis found no significant benefit on fasting glucose, fasting insulin, HbA1c, insulin-resistance measures, or lipid profile. A key counterweight to individual positive studies — it shows that raising NAD+ has not translated into consistent metabolic improvement in humans.
NAD+ precursor supplementation in human ageing: clinical evidence and challenges
Review (Nature Metabolism 2025) appraising the clinical evidence for NAD+ precursor supplementation (NMN, NR) in human ageing and the obstacles to translation. It contrasts the robust preclinical and pharmacokinetic case — precursors reliably raise NAD+ — with the limited and inconsistent human outcome data, and discusses challenges including dose, tissue-specific NAD+ effects, trial design, and the gap between mouse healthspan benefits and human results. A current, balanced statement of where the field actually stands.
FDA position on NMN (nicotinamide mononucleotide) as a dietary supplement
Regulatory record of the contested status of the NAD+ precursor NMN as a dietary supplement in the United States. In late 2022 the FDA concluded that NMN was excluded from the dietary-supplement definition because it had been authorized for investigation as a new drug before being marketed as a supplement. After industry challenge, the FDA reversed this interpretation in September 2025, confirming that NMN is not excluded and may be lawfully marketed as a supplement, citing evidence of supplement sales predating the drug investigation. It illustrates the unsettled regulatory boundary around popular NAD+ precursors and is not a finding on efficacy.
https://www.nutraingredients.com/Article/2025/09/30/fda-declares-nmn-lawful-in-dietary-supplements/