The NMN Reality Check
If you’ve been even half interested in longevity science over the past few years, you will have come across the purported benefits of boosting your NAD levels. As David Sinclair discussed his elderly father being “super fit” at 85 years old “with zero aches and pains or diseases” (9), most of us thought “I want a bit of whatever he is having!”
Many of us went off to try the next supplement. NAD, NMN, NR, nicotinamide…. Tablets, infusions or should we just all snort it? It was all enough to make your head spin. Going back to basic biochemistry and molecular biology was fun for some of us. For the rest of you folks out there, just getting the right supplement was key.
NMN (β-nicotinamide mononucleotide) is a precursor to NAD+ and is crucial for cellular energy and repair. It is present in every cell of our body. It depletes with age, so it would make sense that if you replaced it, you’d probably feel more energized and potentially younger.
Safety of NMN
So far, no safety concerns have been identified in human trials (1, 2, 5, 6).
Across about 120–130 adults aged 20–65 years, clinical studies have tested NMN in doses between 250 mg and 900 mg per day over 6–12 weeks (1, 2, 5, 6).
All reported that NMN was safe and well tolerated, with no serious adverse events.
Documented Benefits
Improved insulin sensitivity in pre-diabetic postmenopausal women (3).
Improved aerobic capacity in amateur runners (4).
Improved functional capacity (6-minute walk test) and possibly sleep quality in middle-aged adults (2).
Increased muscle strength and NAD⁺ metabolites in older men (5).
While results are encouraging, studies were small and short, so NMN remains promising but preliminary.
Regulation
As a doctor in the field of functional medicine & longevity medicine, getting the right molecule into the body is key. Everyone knows this about blood pressure medication. Too much and you’re dizzy. Too little and you’re risking a heart attack or stroke.
The good thing about blood pressure pharmaceuticals is that I know exactly what I’m giving you. I can titrate the dose.
But in the grey market of nutraceuticals and supplements, it becomes a very large challenge. They are somewhat regulated, but no where near to the level that pharmaceuticals are.
So what are you really getting?
Professor Andrea Maeir and colleagues from the National University of Singapore researched the quality of multiple brands of NMN and Urolithin A in 2024 (7). I was delighted to hear about this work and I awaited the results with baited breath.
They tested 18 commercially available NMN supplements. The findings?
They found that the actual NMN content ranged from undetectable to 99.2% of what was on the label.
3 products had no measurable NMN at all.
Another study by Chromatix in 2021 showed similar findings (8). They checked 22 different brands of NMN.
Why the variation?
If you’re feeling generous, you can attribute it to the molecule degrading over time. NMN is an unstable molecule and it is degraded easily, particularly under light, heat or humidity (7).
If you’re a sceptic and start researching the difficulties and costs of production, then perhaps some players are being less than honest. The highest-purity NMN (> 99%) costs hundreds to thousands of USD per kilogram at wholesale. The manufacturing process is very complex and therefore expensive.
How can I make sure I actually get NMN?
There is no easy answer to this. It’s work, work and more work I’m afraid!
NMN supplements can vary wildly in quality — and price.
Check the price. Genuine NMN isn’t cheap to make. Clinical-grade material costs around £0.50–£1 per 100 mg, so a month’s supply of 500 mg/day should be £80–£150. If it’s a tenth of that, it’s probably counterfeit or degraded.
Look for third-party testing. Trusted seals like NSF, Informed Choice, or USP Verified suggest that someone other than the seller has actually tested what’s in the capsule.
Ask (or look) for a Certificate of Analysis (CoA).
It should list an independent lab, batch number, and testing method (HPLC or LC-MS).
Realistically, few of us will check every document—but brands that offer them publicly are usually more trustworthy.Check the batch number.
A printed batch ID and expiry date show that the product comes from a controlled production line, not an anonymous bulk powder bag.Inspect packaging.
NMN breaks down with heat and moisture. Choose opaque or foil packs with desiccants and an expiry date under two years.Prefer local suppliers.
UK or Swiss distributors registered with the FSA (Food Standards Agency) or FSVO (Bundesamt für Lebensmittelsicherheit und Veterinärwesen) are safer bets than Amazon, Galalxus or the like.
In longevity medicine, “cheap” almost always means unstable, mislabeled, or fake. If the science matters to you, buy as though it does.
Dr Natalia Ciapryna is a UK-trained physician with a special interest in longevity and functional medicine. She is passionate about helping people maintain their health and vitality so they can prevent disease and live their best life — at any age. Drawing on over 20 years of international clinical experience, she combines cutting-edge research in ageing biology with practical, evidence-based guidance that anyone can apply. Through The Expat MD, she aims to make longevity science accessible, balanced, and truly useful for everyday health decisions.
References
Fukamizu Y, et al. Safety evaluation of β-nicotinamide mononucleotide oral administration in healthy adult men and women. Sci Rep. 2022; 12(1): 14442. PubMed 36044324 | doi:10.1038/s41598-022-18272-y
Yi L, et al. 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; 45(1): 29–43. PubMed 36472011 | doi:10.1007/s11357-022-00705-1
Yoshino M, et al. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science. 2021; 372(6547): 1224–1229. PubMed 34140314 | doi:10.1126/science.abe9985
Liao B, et al. Oral nicotinamide mononucleotide supplementation improves ventilatory threshold and aerobic capacity in amateur runners. J Int Soc Sports Nutr. 2021; 18(1): 54. PubMed 34773944 | doi:10.1186/s12970-021-00463-0
Igarashi M, et al. Nicotinamide mononucleotide supplementation enhances muscle strength and metabolic parameters in healthy older men. npj Aging. 2022; 8(1): 3. PubMed 35596648 | doi:10.1038/s43587-022-00154-x
Katayoshi S, et al. β-Nicotinamide mononucleotide supplementation and arterial stiffness in middle-aged adults: a randomized controlled trial. Sci Rep. 2023; 13(1): 6783. PubMed 37165856 | doi:10.1038/s41598-023-33964-3
National University of Singapore – Medicine Faculty. Significant discrepancies between actual and labelled amount of anti-ageing ingredients in supplements – NUS Medicine study. 2024. Link
ChromaDex Inc. Analysis of NMN-containing supplements commercially available in the marketplace. 2021. Link
Sinclair D. Instagram post describing his father at age 85 as “super fit … with zero aches, pains or diseases.” 2023. Link
