Healthspan.

NMN vs NR: what the human evidence shows

Evidence grade: Moderate. Raising blood NAD+ is well shown in human trials for both. Effects on health outcomes come from small, short trials with mixed results. Effects on aging itself are not shown. See how we grade.

What NMN and NR are

NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) are both precursors of NAD+, a molecule cells use for energy metabolism and signalling. A 2018 review in Cell Metabolism describes NAD+ levels declining with age, and restoring NAD+ in old or diseased animals improving health and extending lifespan [1]. That is animal evidence. The question for people is narrower: do these pills raise NAD+, and does that change anything you can feel or measure?

If you want the short version on NMN alone, read NMN: what is actually proven.

Do they raise NAD+ in people?

Yes, for both. This is the best-supported part of the story.

NR. In the first human pharmacokinetic trial, single doses of 100, 300 and 1,000 mg of NR raised the blood NAD+ metabolome in a dose-dependent way [2]. An 8-week placebo-controlled trial in overweight but otherwise healthy adults found that 100, 300 and 1,000 mg per day raised whole-blood NAD+ by 22%, 51% and 142% within two weeks, and the rise held for the rest of the study [3]. A 2 × 6-week crossover trial in healthy middle-aged and older adults found NR was well tolerated and stimulated NAD+ metabolism [4]. In 12 older men, 1 g per day for 21 days raised the NAD+ metabolome in muscle, not just blood [5].

NMN. In healthy older men, 250 mg per day for 6 or 12 weeks raised blood NAD+ and related metabolites [6]. In a 60-day trial of 80 healthy middle-aged adults, 300, 600 and 900 mg per day all raised blood NAD+ compared with placebo, with the highest levels at 600 and 900 mg [7].

Do they change health outcomes?

This is where the evidence thins out.

NMN. In a 10-week trial in postmenopausal women with prediabetes who were overweight or obese, NMN increased muscle insulin sensitivity, measured with a clamp test [8]. In older men, gait speed and one grip test improved, but the authors called these nominal results that need larger studies, and body composition did not change [6]. The 80-person trial reported longer six-minute walking distance, but insulin resistance (HOMA-IR) did not change [7].

NR. In 40 obese, insulin-resistant men, 2,000 mg per day for 12 weeks did not improve insulin sensitivity or glucose metabolism [9]. In older men, NR lowered some circulating inflammatory markers but did not change mitochondrial function in muscle [5]. The crossover trial said blood pressure and arterial stiffness are worth testing in future trials. That is a hypothesis, not a result [4].

So: one positive metabolic result for NMN in a specific group, one negative metabolic result for NR in another group, and some early physical-function signals. We know of no trial showing that either one slows aging.

Safety in the trials so far

Both were well tolerated in the trials above. In the 8-week NR trial there were no reports of flushing and no significant differences in adverse events between NR and placebo [3]. The 12-week trial at 2,000 mg of NR per day reported no serious adverse events [9]. For NMN, single doses up to 500 mg in 10 healthy men caused no significant clinical symptoms [10], and the 60-day trial found no safety issues up to 900 mg per day [7].

These trials were short, from a single dose to 12 weeks, and small. Long-term safety is not known. If you take medication, have a chronic condition, or are pregnant, talk to a doctor before starting either one.

Who funded the studies

Read the conflict-of-interest lines. Several key trials had commercial ties. The first NR pharmacokinetic trial was sponsored by the NR supplier, and some authors owned stock in it [2]. Some authors of the 250 mg NMN trial were employees of a company in the NMN business [6]. The lead author of the 80-person NMN trial was a company employee [7]. Industry funding does not make a result wrong, but it is a reason to want independent replication.

Regulatory status in the US

In a September 2025 letter, the FDA concluded that NMN is not excluded from the definition of a dietary supplement, reversing its earlier position [11]. The 2019 NR trial paper states that a crystal form of NR chloride is generally recognized as safe (GRAS) for use in foods [3]. Neither status means the product works. It is about whether it may be sold.

So which one?

We are not aware of a head-to-head trial comparing NMN and NR on any health outcome. Both raise NAD+. Neither has been shown to affect aging in people. If you try one, treat it as an experiment, not a treatment. Pick one product, keep the dose within what trials have tested, and do not drop the basics. Sleep, strength training and aerobic fitness have far stronger evidence; see our NAD protocol for how we place NAD precursors among them.

See the NAD+ precursor comparison →

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Frequently asked questions

Is NMN better than NR?

No trial we know of has compared them head to head on a health outcome. Both raise blood NAD+ in human trials. Neither has been shown to slow aging in people.

Do NMN and NR actually raise NAD+ levels?

Yes. Placebo-controlled human trials show that both raise NAD+ in blood, and one small trial showed NR raised NAD+ metabolites in older men's muscle.

Are NMN and NR safe?

In short trials lasting from a single dose up to 12 weeks, both were well tolerated, with no serious safety signals reported. Long-term safety is unknown. Talk to a doctor if you take medication or have a medical condition.

Can NMN or NR reverse aging?

There is no human evidence for that. The human trials measured NAD+ levels and a few health markers, with mixed results. Lifespan and aging effects come from animal studies.

Is NMN legal to sell as a supplement in the US?

In a September 2025 letter, the FDA concluded that NMN is not excluded from the definition of a dietary supplement. That is a legal status, not proof that it works.

Sources

  1. Therapeutic Potential of NAD-Boosting Molecules: The In Vivo Evidence. Cell Metabolism, 2018. Review. https://pubmed.ncbi.nlm.nih.gov/29514064/
  2. Nicotinamide riboside is uniquely and orally bioavailable in mice and humans. Nature Communications, 2016. https://pubmed.ncbi.nlm.nih.gov/27721479/
  3. Safety and Metabolism of Long-term Administration of NIAGEN (Nicotinamide Riboside Chloride) in a Randomized, Double-Blind, Placebo-controlled Clinical Trial of Healthy Overweight Adults. Scientific Reports, 2019. https://pubmed.ncbi.nlm.nih.gov/31278280/
  4. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nature Communications, 2018. https://pubmed.ncbi.nlm.nih.gov/29599478/
  5. Nicotinamide Riboside Augments the Aged Human Skeletal Muscle NAD+ Metabolome and Induces Transcriptomic and Anti-inflammatory Signatures. Cell Reports, 2019. https://pubmed.ncbi.nlm.nih.gov/31412242/
  6. Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men. npj Aging, 2022. https://pubmed.ncbi.nlm.nih.gov/35927255/
  7. The efficacy and safety of β-nicotinamide mononucleotide (NMN) supplementation in healthy middle-aged adults: a randomized, multicenter, double-blind, placebo-controlled, parallel-group, dose-dependent clinical trial. GeroScience, 2023. https://pubmed.ncbi.nlm.nih.gov/36482258/
  8. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science, 2021. https://pubmed.ncbi.nlm.nih.gov/33888596/
  9. A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men: safety, insulin-sensitivity, and lipid-mobilizing effects. The American Journal of Clinical Nutrition, 2018. https://pubmed.ncbi.nlm.nih.gov/29992272/
  10. Effect of oral administration of nicotinamide mononucleotide on clinical parameters and nicotinamide metabolite levels in healthy Japanese men. Endocrine Journal, 2020. https://pubmed.ncbi.nlm.nih.gov/31685720/
  11. FDA response to citizen petition on the regulatory status of beta-nicotinamide mononucleotide (NMN), Docket FDA-2023-P-0872 (letter to Natural Products Association and Alliance for Natural Health USA). U.S. Food and Drug Administration (copy hosted by the American Herbal Products Association), 2025. Letter dated September 29, 2025 (the PDF header prints the year as 2029, an apparent typo). https://www.ahpa.org/Files/PDFs/AHPAUpdate/25_0930%20NPA%20NMN%20FDA%20CP%20Response.pdf