There’s no shortage of excitement around NMN (nicotinamide mononucleotide), a compound that serves as a direct precursor to NAD⁺, the coenzyme behind cellular energy production, repair, and metabolic regulation.
But while animal studies kicked off the excitement, the real question has always been: what does NMN actually do in humans? Now, with multiple clinical trials published, we have answers. And the results are not just promising, they’re strong.
This summary focuses only on peer-reviewed human studies, outlining what researchers found, where the evidence is consistent, and what’s still being explored.
What is NMN, and why NAD⁺ matters
NAD⁺ levels decline with age, and that’s not just a biochemical footnote: it has a direct effect on how our cells produce energy, repair themselves, and resist stress. Researchers began looking for ways to restore NAD⁺, and NMN emerged as one of the most promising compounds to do that.
Unlike many “anti-ageing” ingredients, NMN has a clear mechanism: it converts into NAD⁺ in cells, helping restore levels that typically drop as we get older. The open question was: does supplementing NMN actually lead to measurable benefits in people?
Thanks to a wave of well-structured studies published over the past few years, we now know the answer.
1. NMN raises NAD⁺ levels and improves physical endurance
Study: Geroscience, 2023 – PMID: 36482258
In this 60-day placebo-controlled trial, 80 healthy middle-aged adults were given NMN at doses of 300, 600, or 900 mg daily. The results showed a clear dose-dependent increase in blood NAD⁺ levels, confirming that oral NMN is well absorbed and bioactive.
Those in the NMN groups also walked significantly farther in the 6-minute walk test compared to placebo, with improvements most pronounced in the 600 and 900 mg groups. Participants taking NMN also reported better self-rated health.
Bottom line: NMN supplementation improved NAD⁺ status, preserved biological age, and enhanced endurance in healthy midlife adults.
2. NMN supports cardiometabolic health
Study: J Clin Endocrinol Metab, 2023 – PMID: 36740954
This short-term study gave 1000 mg/day of NMN (as MIB-626) to overweight or obese adults aged 45+. After just 28 days, researchers observed several meaningful changes:
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Body weight decreased by nearly 2 kg
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Diastolic blood pressure dropped significantly
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LDL and non-HDL cholesterol were both reduced
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Circulating NAD⁺ and related metabolites increased significantly
Muscle strength, insulin sensitivity, and liver fat remained unchanged, but the improvements in weight and cardiovascular markers are notable, especially for a 4-week study.
Takeaway: NMN appears to support lipid metabolism and cardiovascular health, particularly in metabolically at-risk populations.
3. NMN enhances NAD⁺ metabolism and may reduce arterial stiffness
Study: Sci Rep, 2023 – PMID: 36797393
In this 12-week trial, 36 healthy middle-aged adults received 250 mg/day of NMN (125 mg twice daily). Researchers found significantly higher levels of serum nicotinamide in the NMN group, reflecting increased NAD⁺ metabolism. Arterial stiffness, measured by pulse wave velocity, tended to improve, although the difference wasn’t statistically significant.
Importantly, no adverse events were reported, and participants tolerated the supplement well.
Conclusion: NMN was safe, increased NAD⁺ turnover, and may contribute to better vascular function over time.
4. NMN improves sleep and fatigue
Study: Nutrients, 2022 – PMID: 35215405
This study explored whether timing matters. 108 older adults took 250 mg/day of NMN or placebo for 12 weeks, either in the morning or afternoon. While all groups showed some improvement, the afternoon NMN group (NMN_PM) had the strongest outcomes:
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Reduced drowsiness
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Improved lower body strength (5x sit-to-stand test)
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Better global sleep quality scores
The timing effect may relate to how NAD⁺ levels fluctuate over the day, or how NMN interacts with circadian rhythms.
Summary: Taking NMN later in the day may be more effective for combating fatigue and improving sleep in older adults.
5. NMN helps preserve walking speed and sleep quality
Study: Geroscience, 2024 – PMID: 38789831
In this 12-week double-blind trial, 60 older adults received 250 mg/day of NMN or placebo. While primary motor function outcomes (like stepping tests) didn’t differ significantly, the NMN group walked faster, and blood levels of NAD⁺ and related metabolites rose.
Participants also showed better scores on sleep quality questionnaires, particularly in the domains of daytime dysfunction and overall sleep satisfaction. Again, no side effects were reported.
What it means: NMN may help maintain mobility and support sleep in ageing adults, even when more intensive physical outcomes are unchanged.
6. NMN changes muscle metabolism in runners
Study: Adv Nutr, 2023 – PMID: 37619764
This trial enrolled healthy amateur runners to explore whether NMN enhances performance. After 6 weeks of 300 mg/day, NAD⁺ levels and related metabolites increased in muscle, plasma, and urine. However, running speed and endurance didn’t change significantly.
This isn’t surprising: in already-fit individuals, energy metabolism may not be a limiting factor. But the consistent NAD⁺ increase confirms biological activity in skeletal muscle.
Key point: NMN reliably boosts NAD⁺ in muscle, but performance outcomes may depend on the baseline fitness of the user.
7. NMN may hold potential in neurodegenerative diseases
Study: Biomed Pharmacother, 2023 (PMID: 39053426)
In a series of in vitro experiments using Alzheimer’s disease cell models, NMN demonstrated clear neuroprotective activity. Researchers observed that NMN enhanced autophagy, reduced the accumulation of toxic tau protein, and activated the Nrf2/Keap1/NQO1 pathway, a key cellular defence mechanism against oxidative stress.
When autophagy or Nrf2 signalling was chemically inhibited, these beneficial effects disappeared, strongly suggesting that NMN’s neuroprotective effects rely on both mechanisms working in tandem.
Summary: In human neuron-like cells, NMN reduced oxidative stress and promoted tau clearance through well-defined cellular pathways, pointing to potential therapeutic relevance in neurodegenerative disease.
What NMN Does in Humans
Across human trials, NMN consistently shows:
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Increases in NAD⁺ levels and related metabolites
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Improved walking performance and muscle function in older adults
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Benefits for sleep quality and afternoon fatigue
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Reductions in cholesterol, blood pressure, and body weight (in at-risk groups)
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Strong safety and tolerability, even at doses up to 1000 mg/day
Results depend on age, baseline health, and dose, but NMN is clearly doing something. And in several studies, it’s doing something meaningful.
Want to try NMN that’s actually aligned with the research?
Every study you’ve just read used pure NMN, no blends, no additives, just one ingredient at a clinically relevant dose. That’s exactly what you’ll find in Simply Nootropics Ageless NMN.
Ageless NMN is formulated to match the protocols used in human trials, it’s clean and bioavailable, and third-party tested for quality and purity. If your goal is to support long-term energy, recovery, and healthy ageing, start with what the research actually supports.
