NAD+ falls with age. That part is not in dispute and it is not what this page is about. What is in dispute is everything sold on the back of it — and the gap between those two things is wider than the marketing lets on.
Every compound, and the trials behind it
Counts run against PubMed on 2 September 2026, restricted to randomised controlled trials. The exact searches are at the bottom.
| Compound | Randomised trials | What it is |
|---|---|---|
| Niacin / nicotinic acid the original precursor, costs cents | 559 | Studied for seventy years, mostly for cholesterol. Same pathway. |
| Nicotinamide vitamin B3, cheap | 292 | Well studied, largely in dermatology. |
| Resveratrol the 2000s longevity molecule | 277 | Not a precursor. Included because it is sold beside them. |
| Nicotinamide riboside premium longevity supplement | 32 | The one most often sold as an anti-ageing product. |
| NMN premium longevity supplement | 31 | Sold interchangeably with NR. |
| NAD+ intravenous clinic administered | 21 | Fewer trials than the oral route, not more. |
Niacin is the original NAD+ precursor. It costs cents, it has been studied since the 1950s, and it has 559 randomised trials. The two compounds sold as longevity supplements have 32 and 31 between them.
But the number that matters is inside the 32
Split nicotinamide riboside's trials by what they actually measured.
That is the whole industry in one line. The evidence overwhelmingly shows that these supplements raise a number in a blood sample. It very rarely asks whether raising that number changes anything you would notice.
A raised biomarker is not a result
It is a reasonable hypothesis that restoring NAD+ towards youthful levels helps. It is not a finding. The trials that would turn one into the other are the four, not the thirteen — and four is not enough to settle anything.
What the reviews concluded
A 2025 systematic review and meta-analysis in the Journal of Cachexia, Sarcopenia and Muscle pooled the randomised trials of NMN and NR on skeletal muscle mass and function in older adults — the outcome closest to why most people take it. Its own summary states that evidence for their effects in older adults "remains inconclusive".
A 2025 review in Nature Metabolism covering NAD+ precursor supplementation in human ageing is titled, in part, "clinical evidence and challenges". The challenges are the point.
The injectable route does not fix this
Oral precursors face absorption and first-pass metabolism, which is the usual argument for injections and nasal sprays. It is a reasonable argument about pharmacokinetics.
It is not an argument from outcomes. Intravenous NAD+ has 21 randomised trials — fewer than the oral route, not more. Anyone telling you the injection is proven where the capsule is not has the literature backwards.
So what would make this worth doing
Two things, and neither is a bottle bought on trust.
Measurement. If the entire claim rests on a biomarker, then not measuring the biomarker is spending money on faith. Baseline, and again after.
Someone who can tell you to stop. The four functional trials are the honest reason to be uncertain. A protocol that nobody reviews is a protocol that never ends, whatever it is or is not doing.
The searches, so you can check the table
Paste these into PubMed exactly as written. Counts drift as trials report; where this page and PubMed disagree, PubMed is right and this page is out of date.
("nicotinamide riboside") AND randomized controlled trial[pt]
("nicotinamide mononucleotide" OR "NMN") AND randomized controlled trial[pt]
("nicotinic acid" OR niacin) AND randomized controlled trial[pt]
"nicotinamide" AND randomized controlled trial[pt]
"resveratrol" AND randomized controlled trial[pt]
("NAD+" OR "nicotinamide adenine dinucleotide") AND (intravenous OR injection
OR infusion) AND randomized controlled trial[pt]
The split inside those 32:
"nicotinamide riboside" AND ("NAD+ levels" OR "NAD levels"
OR "NAD+ concentration") AND randomized controlled trial[pt]
"nicotinamide riboside" AND ("physical function" OR "muscle function"
OR "exercise capacity" OR "cognitive function" OR mortality)
AND randomized controlled trial[pt]
References
- Prokopidis K, et al. The Effect of Nicotinamide Mononucleotide and Riboside on Skeletal Muscle Mass and Function: A Systematic Review and Meta-Analysis. J Cachexia Sarcopenia Muscle 2025;16(3):e13799. PMID 40275690.
- Vinten KT, et al. NAD+ precursor supplementation in human ageing: clinical evidence and challenges. Nat Metab 2025;7(10):1974–1990. PMID 41083806.
- NAD+ supplementation for anti-aging and wellness: a PRISMA-guided systematic review. Ageing Res Rev 2026. PMID 41655607.
- Trial counts: PubMed, queried 2 September 2026, filtered to randomised controlled trials.
This page reports published research. It is not medical advice, contains no doses, and is not a recommendation to take anything.