Do NAD+ supplements work? What human studies measured

Evidence limits

What is the downside of NAD+ in the research record?

Cost and product quality sit outside these studies. What the studies do cover is adverse events, and NAD+ side effects sets them out trial by trial. The same page covers the FDA's reports on compounded NAD+.

Small samples are the common thread. A 2023 review of trials of dietary NAD+-boosting compounds notes that small sample sizes limit interpretation of physiological outcomes, and that study durations vary greatly between interventions (Freeberg et al., The Journals of Gerontology: Series A, 2023).

Do NAD+ supplements work, according to human trials?

A 2026 systematic review of 33 human studies found consistent biochemical target engagement, meaning circulating NAD-related metabolites rose, and heterogeneous, often null results for functional, metabolic and vascular outcomes, across studies that differed in products, groups and length (Gallagher and Emmanuel, Ageing Research Reviews, 2026). A 2024 meta-analysis of 8 randomised NMN trials with 342 adults found no significant effect on fasting glucose, fasting insulin, glycated haemoglobin or lipid profile, within the limits of short trials in mostly healthy adults (Chen et al., Current Diabetes Reports, 2024).

Raising a blood marker and changing a health outcome are different results. The table after these sections lists the outcomes one by one, with a separate source and limitation for each finding.

A 2018 review of NAD+ intermediates describes the pharmacokinetics and metabolic fates of NMN and NR as still under intensive investigation, and says preclinical results were still to be tested for translation to human health; it summarises studies and tested nothing itself (Yoshino et al., Cell Metabolism, 2018).

What does research show NMN does in the body?

Nicotinamide mononucleotide (NMN) is a precursor that the body converts toward NAD+, and in a 12-week trial of 30 healthy adults, whole-blood NAD+ rose significantly after NMN compared with placebo (15 against 15), and nicotinic acid mononucleotide, a related molecule, also rose though NMN itself did not; the trial was small and measured blood markers (Okabe et al., Frontiers in Nutrition, 2022). In a 10-week randomised trial of 25 postmenopausal women with prediabetes who were overweight or obese, muscle insulin sensitivity and insulin signalling rose with NMN, a small single-trial result that applies to that group only (Yoshino et al., Science, 2021).

In a trial of 42 healthy older men randomised to NMN or placebo, with 20 completing 12 weeks, blood NAD+ rose and gait speed and a grip test showed nominally significant changes that the authors say need validation in larger studies, with no significant effect on body composition (Igarashi et al., npj Aging, 2022). In a randomised trial of 80 healthy middle-aged adults with three NMN groups and a placebo group, six-minute walking distance was higher in the NMN groups than placebo at day 30 and day 60, while HOMA-IR, a marker of insulin resistance, did not differ, and the trial ran for 60 days only (Yi et al., GeroScience, 2023).

These are separate results from separate trials.

What have studies of nicotinamide riboside found?

In a crossover trial with 30 healthy middle-aged and older adults randomised and 24 completing, Martens et al. measured NAD+ metabolism, blood pressure and arterial stiffness; cardiovascular findings were exploratory and the overall comparisons did not remain significant after correction for multiple comparisons (Nature Communications, 2018). In a 12-week randomised trial of 40 obese men, NR did not improve insulin sensitivity, a result that applies to that group only (Dollerup et al., American Journal of Clinical Nutrition, 2018). In a 30-day phase 1 trial of 30 newly diagnosed Parkinson's patients, brain NAD levels rose by a variable amount with NR, and mild clinical improvement was reported in recipients whose levels rose; the trial was small and its authors call for larger trials (Brakedal et al., Cell Metabolism, 2022).

In a placebo-controlled crossover trial of 13 overweight or obese adults given NR for 6 weeks, fat-free mass was 62.7% of body mass after NR against 61.3% after placebo and sleeping metabolic rate increased, with no effect on insulin sensitivity or mitochondrial function, in a very small group (Remie et al., American Journal of Clinical Nutrition, 2020).

In a 24-week randomised trial of 58 people with long COVID, NR raised NAD+ but produced no significant between-group difference in cognition, the primary outcome, in a trial where 32.4% of the NR group had dropped out by 10 weeks and 51.4% by 20 weeks, a result for that condition only (Wu et al., EClinicalMedicine, 2025). Each trial measured different outcomes in a different group, so the results do not add up to one verdict.

Do NAD+ precursors change body weight?

No trial opened for this page reported weight gain as an effect of NAD+ precursors; this limited report check does not establish that weight gain cannot occur. In a 28-day randomised trial of 30 overweight or obese adults, body weight was 1.9 kg lower with NMN than with placebo, a result from a small physiologic study in which weight was one of many outcomes measured (Pencina et al., Journal of Clinical Endocrinology and Metabolism, 2023). A 12-week randomised trial of 40 obese men found no effect of NR on body composition, a result limited to that group and period (Dollerup et al., American Journal of Clinical Nutrition, 2018).

Animal studies measured weight too. In a 12-month mouse study, NMN suppressed age-associated body weight gain, a mouse result that does not establish the same change in people (Mills et al., Cell Metabolism, 2016). In a 91-day rat study, body weight and weight gain fell in the highest NMN group, and the study reports this as a toxicology finding and not as a weight outcome, a rat result that does not establish a human result (Turner et al., Frontiers in Pharmacology, 2021).

Trials of other body measures differ. In a small trial of 42 healthy older men randomised to NMN or placebo, with 20 completing 12 weeks, Igarashi et al. found no significant effect of NMN on body composition, a result that applies to healthy older men over that period only (npj Aging, 2022).

What do trials show about NAD+ precursors and energy or fatigue?

In a 12-week randomised trial of 108 older Japanese adults split into four groups, one NMN group had the largest effect sizes for drowsiness and sit-to-stand time, but its matching placebo group also improved on drowsiness and sit-to-stand time improved in every group, so the trial cannot separate NMN from placebo effects (Kim et al., Nutrients, 2022). In a 24-week randomised trial of 58 people with long COVID, NR raised NAD+ without a significant between-group difference in fatigue severity, a result for that condition only (Wu et al., EClinicalMedicine, 2025).

In a randomised trial of 30 overweight or obese adults given NMN for 28 days, muscle fatigability, aerobic capacity and stair-climbing power did not differ significantly from placebo, in a small short trial (Pencina et al., Journal of Clinical Endocrinology and Metabolism, 2023).

NAD+ has a central role in cell energy chemistry, which is why energy is the natural question. A review describes NAD+ as a coenzyme for redox reactions, central to energy metabolism (Covarrubias et al., Nature Reviews Molecular Cell Biology, 2021). A role in energy chemistry inside cells is not the same as a result a person can feel, and the trials above measured the second thing.

What do studies show about NMN and skin, including the face?

No human trial of NMN or NR with a facial-skin or wrinkle outcome turned up in a PubMed search on 14 October 2026. The skin evidence found comes from mice and from one rare-disease trial. In SKH-1 hairless mice exposed to UV-B light for 10 weeks, NMN treatment reduced epidermal thickening and wrinkle formation and improved hydration and elasticity, a mouse result that does not establish the same effect in people (Kim et al., Antioxidants, 2025). In a randomised crossover trial in Werner syndrome, a rare inherited aging disorder, with nine patients randomised and six completing, skin ulcer area decreased during NR treatment, a secondary measure in a very small trial of a genetic condition (Shoji et al., Aging Cell, 2025).

A mouse result belongs to the mouse, and hairless mice differ from people in their skin. The Werner syndrome trial had safety as its primary endpoint, and skin ulcers were a secondary measure in people with a genetic condition that shapes their skin.

Together these papers do not show what NMN does to a healthy adult's face or to sagging skin. They show where the evidence stops.

What do studies show about NMN and hair growth?

The hair evidence found for NMN is from mice and cultured cells, not people. In a 2024 paper, NMN reversed hair follicle atrophy, hair thinning and hair sparsity that dihydrotestosterone, a male sex hormone, caused in mice, a result the authors compared with minoxidil, a hair-loss medicine, and it protected cultured human dermal papilla cells under the same hormone; these are mouse and cell-culture results that do not establish a hair effect in people (Xu et al., Molecules, 2024). A PubMed search on 14 October 2026 for NMN, NR or NAD+ with hair terms returned no human trial with a hair outcome.

Dermal papilla cells are the cells at the base of a hair follicle that signal hair growth. A culture dish and a mouse are two steps from a person, and the paper does not claim a human result.

How does NAD+ relate to aging, according to the research?

An observational brain-imaging study of 17 healthy volunteers aged 21 to 68 found age-dependent reductions in NAD+ and total NAD, an association that does not show a cause (Zhu et al., Proceedings of the National Academy of Sciences, 2015).

In a 12-month study of normal aging in mice, NMN suppressed age-associated weight gain and was followed by changes in several measured functions, a mouse result that does not establish the same changes in people (Mills et al., Cell Metabolism, 2016). The 2026 systematic review of 33 human studies found that results on healthspan-relevant outcomes were heterogeneous and often null, across differing interventions and short studies that do not establish effects on human lifespan (Gallagher and Emmanuel, Ageing Research Reviews, 2026).

A decline that accompanies aging is a correlation. Showing that the decline drives aging in people would take long trials with outcomes that matter to patients, and none of the trials above ran that long.

What has been studied about NAD+ itself, including IV and oral NAD+?

Few human trials test NAD+ itself, and the evidence for NAD+ given directly is thin. A 2026 systematic review found no eligible outcomes trial of intravenous or intramuscular NAD+ for anti-aging or wellness indications and one nonrandomised NMN study that mainly added short-term safety and biomarker information (Gallagher and Emmanuel, Ageing Research Reviews, 2026). A 2026 review states that NAD+ given directly is less well characterised than precursor supplementation and lacks robust clinical validation (Pandolfi et al., Molecular Biology Reports, 2026). The one pilot opened for this page, in 11 men, measured blood and urine levels and not health outcomes, so it is too small to show effects or rates of harm (Grant et al., Frontiers in Aging Neuroscience, 2019).

NADH, the reduced partner of NAD+, has its own small literature. In a 1999 placebo-controlled crossover trial of 26 people with chronic fatigue syndrome, 8 responded favourably to NADH and 2 to placebo, a small trial after which the authors planned an open-label study in a larger cohort (Forsyth et al., Annals of Allergy, Asthma and Immunology, 1999). A 12-week randomised placebo-controlled trial of 207 people with ME/CFS (104 against 103) tested NADH together with coenzyme Q10 and reported lower cognitive fatigue scores within the treated group over time, a combination trial that cannot separate the two ingredients (Castro-Marrero et al., Nutrients, 2021).

Those NADH trials are not trials of NAD+. NAD+ side effects covers what has been recorded for NAD+ drug products.

Is research-use NAD+ the same material these studies measured?

No. Every result on this page describes a trial product given to enrolled participants, or an animal or cell experiment, and none describes research-use reference material. Research material is not a medicine, is not a substitute for one, and is not for human or animal use. The site catalogue lists NAD+ reference material as a laboratory item. The study results describe what happened inside those studies, and they say nothing about material outside them. The NAD+ research guide and Is NAD+ legal in Australia? cover the rest.