NMN, nicotinamide mononucleotide, is a naturally occurring compound found in small amounts in foods such as broccoli, avocado and cabbage. Inside the body, NMN is converted into NAD+, a molecule that supports energy production, DNA repair and cellular health.
NAD+ levels decline steadily with age. This decline is one of the reasons scientists have linked NAD+ to ageing and age related decline. The current interest in NMN comes from the idea that restoring NAD+ levels may support healthier ageing.
The David Sinclair influence
Much of the global attention on NMN comes from the work of David Sinclair, a professor of genetics at Harvard Medical School.
Sinclair’s research focuses on the biology of ageing, particularly sirtuins which are proteins involved in cellular repair and longevity, NAD+ metabolism and epigenetic ageing.
His laboratory has shown in animal models that boosting NAD+ levels can improve mitochondrial function, physical endurance and markers linked to biological ageing.
In mice, NMN has been linked with increased activity, improved metabolic function and reduced frailty in later life.
Sinclair has consistently stated that animal results do not automatically translate to humans and that long term human studies are still ongoing.
What human research shows so far
Human clinical research into NMN has accelerated since 2020. While still early, the evidence is now more structured and consistent.
Across human trials, NMN supplementation has been shown to increase NAD+ levels. Blood measurements confirm that NMN raises NAD plus in humans, which is its primary biological mechanism.
Studies in people aged 40 to 65 and older show improvements in walking speed, grip strength, endurance and aerobic capacity.
Trials in post menopausal women with prediabetes show improved muscle insulin sensitivity and improved insulin signalling. Other studies show reductions in cholesterol, body weight and blood pressure.
Some trials in adults over 65 report improved sleep quality and reduced daytime fatigue.
Short term studies using doses between 300 mg and 1200 mg daily show NMN is generally well tolerated with no serious adverse effects reported.
What NMN does not currently prove
It is important to stay grounded in the evidence because at present, human studies do not prove that NMN extends human lifespan, reverses biological age or produces dramatic cosmetic anti ageing effects. The benefits seen so far are measurable, focused mainly on energy metabolism and physical function.
Real world experiences including over 50s
While clinical trials provide the most reliable data, real world experiences help illustrate how people describe the effects in everyday life.
Across user reports and early observational studies, people over 50 most commonly describe increased energy and stamina, particularly for walking, exercise and general daily activity. Older adults report improved mobility and physical function, including better walking distance and ease of movement in daily routines.
Individuals with prediabetes or weight concerns report improved blood sugar control and gradual weight reduction, which aligns with insulin sensitivity findings in clinical studies.
Adults over 60 often report sleeping more soundly and waking with more energy, matching emerging data from controlled trials.
Some users also describe subtle improvements in focus and mental clarity, likely linked to improved cellular energy production, although this area is still being studied.
These examples reflect reported experiences that align with current human data rather than unverified claims.
Who might consider NMN
Based on current research, NMN is most commonly explored by adults over 40 experiencing age related energy decline, adults over 50 focused on maintaining mobility and metabolic health, and individuals interested in preventative healthy ageing strategies.
Anyone with existing health conditions or taking medication should seek medical advice before using NMN.
The balanced scientific view
The current scientific position on NMN can be summarised simply.
The biological mechanism is strong because NMN raises NAD+. Animal data is promising. Human data shows modest but measurable benefits. Long term outcomes are still unknown.
I take the approach that incuding NMN can do no harm, and could do a lot of good. I certainly notice I am more mentally alert and take them most days a month.
References and further reading
Yoshino et al 2021 NMN improves insulin sensitivity in prediabetic post menopausal women
Igarashi et al NMN improves physical performance in older adults
Huang et al NMN improves walking endurance in middle aged adults
Pencina et al 2023 NMN improves cholesterol, weight and blood pressure
Multiple human NMN trial summaries from 2020 to 2025
Morifuji et al 2024 NMN supports sleep quality and walking performance
Yi et al 2022 NMN raises NAD plus in humans safely
