NAD+ and precursors: what the evidence shows

What the human research shows

Included because it sits next to the peptides on the same shelves and syringes. The biochemistry is real and the precursors do raise NAD+ — but 'raises a coenzyme' is a marker, not a health outcome, and the outcome trials so far are small and inconclusive.

Evidence profile0–5

Metabolic & weightB2.3
Cardiovascular—0.0
Muscle & growth—0.0
Healing & repair—0.0
Neuro & sleep—0.0
Immune & inflammation—0.0
Sexual & hormonal—0.0
Skin & appearance—0.0
Ageing & longevityD0.0

Each score is confidence × effect size, taken from the best-evidenced benefit in that domain: the grade (A–D) sets the confidence, the measured effect sets the size. Hover a domain to see the outcomes behind it. Adverse effects are excluded and listed separately below.

Outcome	Grade	Effect size	Human studies	Where the evidence comes from
Raising NAD+ levels	BProbable	Moderate	Multiple RCTs (NR, NMN)	Oral nicotinamide riboside and NMN reliably and safely increase blood NAD+ in randomised trials — the one thing that is well established.1
Insulin sensitivity / metabolic health	CWeak	Small	1 small RCT (n=25), contested	A 10-week NMN trial in prediabetic postmenopausal women improved muscle insulin sensitivity — a single small study whose interpretation was publicly disputed and which has not been replicated.2
Anti-ageing / physical function	DNo human evidence	Not measurable	No outcome trials	Despite the marketing, no trial has shown NAD+ or its precursors slow ageing or improve hard clinical outcomes in people. Some trials found no effect on muscle mitochondrial function.3
Safety (oral precursors)adverse	BProbable	Small	Multiple RCTs	Oral NR and NMN are well tolerated in trials up to several months. Intravenous NAD+ is a different matter — unstudied in controlled trials and associated with infusion reactions.1

AMultiple good human trials, consistentBSome human trials, mostly consistentCFew or weak human studiesDAnimal or anecdotal onlyeffect size · red = adverse

Literature searched to 3 September 2026. Human studies only; animal and cell work informs the mechanism section and nothing else.

Registered trials

ClinicalTrials.gov lists 17 interventional studies naming NAD+ and precursors as an intervention — 6 completed, 7 recruiting, and none with results posted to the registry.

A registration is not a result. Anyone can register a study, and many never report — so this list shows what has been attempted, not what has been shown. The graded evidence above is the answer to whether something works.

Study	Phase	Status	Participants	Sponsor	Results
Nicotinamide Mononucleotide in Hypertensive PatientsNCT04903210 · started Jun 2021	Phase 4	Unknown	20*	First Affiliated Hospital, Sun Yat-Sen University	None
Comparisons of NAD Precursors for Neuroenhancement in Glaucoma PatientsNCT06991712 · started May 2025	Phase 2	Recruiting	138*	Christopher Kai Shun Leung	None
Tracing the Metabolic Flux of Orally Administered NAD+ PrecursorsNCT06882096 · started Apr 2025	Phase 1	Recruiting	32*	Metro International Biotech, LLC	None
Metabolic Changes Induced by NMN in Healthy Subjects With Acute Binge DrinkNCT05882214 · started May 2024	Phase 1	Completed	22	Zhejiang Chinese Medical University	None
A Clinical Study of NAD in the Treatment of Immune ThrombocytopeniaNCT06776510 · started Jan 2025	Phase 1	Recruiting	20*	Institute of Hematology & Blood Diseases Hospital, China	None
NAD-brain: a Pharmacokinetic Study of NAD Replenishment TherapyNCT05698771 · started Sept 2022	Phase 1	Completed	12	Haukeland University Hospital	None
Assessing the Safety and Tolerability of NMN in DHDDS-CDGNCT07572825 · started May 2026	Phase 1	Recruiting	8*	Eva Morava-Kozicz	None
Effect of NMN on Muscle Recovery and Physical Capacity in Healthy Volunteers With Moderate Physical ActivityNCT04664361 · started Mar 2021	N/A	Completed	131	Seneque SA	None

9 further studies are registered. Participant counts marked * are the sponsor's estimate, not a final enrolment. Source: ClinicalTrials.gov, read directly from the registry and refreshed weekly.

What it is

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme central to how cells turn food into energy and to the activity of repair and signalling enzymes. Levels fall with age in some tissues, which is the premise behind supplementing it.

You cannot usefully take NAD+ by mouth, so the market sells precursors the body converts into it — nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) — plus intravenous NAD+ drips. None of this is a peptide; it is included because it is marketed and injected alongside them.

How it is thought to work

NR and NMN are converted through the salvage pathway into NAD+, raising its availability for metabolic and repair enzymes. The open question is whether topping up a coenzyme that is not necessarily limiting produces any benefit a person would feel — which is what the outcome trials have so far failed to establish.

What is still unknown

Whether raising NAD+ produces any clinical benefit in healthy people.
Whether NMN and NR differ meaningfully in effect.
The safety and value of intravenous NAD+, which lacks controlled trials entirely.

The molecule and how long it lasts

Identity

Formula: C21H27N7O14P2
Molecular weight: 663.4 g/mol
CAS number: 53-84-9
PubChem: CID 5892

Recorded as nadide, the oxidised coenzyme

PubChem record, read 23 September 2026.

Pharmacokinetics

Route: Intravenous infusion (healthy men, 750 mg over 6 hours)
Half-life: No half-life reported; plasma NAD+ did not rise for the first 2 hours of infusion, then rose about four-fold by 6 hours

From a published human pharmacokinetic study: Grant R, et al. A pilot study investigating changes in the human plasma and urine NAD+ metabolome during a 6 hour intravenous infusion of NAD+. Front Aging Neurosci 2019;11:257

Regulatory status

European Union

Mixed; NMN restricted

NR is an authorised novel food; NMN's food status is unsettled in the EU. Intravenous NAD+ for 'wellness' is an unlicensed medical use.

United States

Supplement status contested

NR is sold as a dietary supplement. The FDA has taken the position that NMN is excluded from the supplement definition because it was investigated as a drug; enforcement is unsettled. IV NAD+ is offered by clinics without FDA approval.

United Kingdom

Supplement / unlicensed

Oral precursors are sold as supplements; IV NAD+ is an unlicensed medical service.

Australia

Supplement / clinic use

Oral products sold as complementary medicines; IV NAD+ offered by some clinics outside standard registration.

Canada

Natural health product / clinic use

Some oral products carry NPN numbers; IV NAD+ is a clinic service, not an approved therapy.

Sport (WADA)

Not prohibited

NAD+ and its precursors are not on the 2026 Prohibited List.

Questions people actually ask

Do NAD+ supplements work?

They reliably raise NAD+ levels and are well tolerated. Whether that produces any health benefit is unproven — the outcome trials so far are small, mixed and, in the most-cited case, contested.

Is NMN or NR better?

No head-to-head trial answers that. Both raise NAD+; neither has shown a clear clinical benefit in a large trial.

What about NAD+ IV drips?

Intravenous NAD+ has essentially no controlled-trial evidence. The randomised data are for the oral precursors, not the drips.

One page per claimed effect

BDoes NAD+ and precursors help with raising NAD+ levels?Multiple RCTs (NR, NMN)
CDoes NAD+ and precursors help with insulin sensitivity / metabolic health?1 small RCT (n=25), contested
DDoes NAD+ and precursors help with anti-ageing / physical function?No outcome trials
BHow common is safety with NAD+ and precursors?Multiple RCTs

References

1
Martens CR, et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults.Nat Commun, 2018;9:128624 adults, crossover; NR raises NAD+, well tolerated.
2
Yoshino M, et al. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women.Science, 2021;372:1224–122925 women, 10 weeks; single, contested trial.
3
Dollerup OL, et al. Nicotinamide riboside does not alter mitochondrial respiration, content or morphology in skeletal muscle from obese and insulin-resistant men.J Physiol, 2020;598:731–754A representative null metabolic result.

Change log

2026-09-03Initial publication. Grade B for raising NAD+, C/D for clinical outcomes.