Benefits
Blood NAD levels in middle-aged and older adults
In placebo-controlled trials, NMN raised blood NAD in healthy middle-aged adults at 300 to 900 mg/day for 60 days and in older adults at 250 mg/day for 12 weeks. Higher blood NAD shows the supplement is absorbed and used, but whether it slows any aspect of aging in people is uncertain.
Walking speed and physical function in older adults
In a 12-week trial of 250 mg/day in 60 older adults, the main stepping test did not differ from placebo, but 4-metre walking time and sleep quality scores were better. A pooled analysis of trials in adults over 60 found no clear benefit for muscle mass, grip strength or walking speed.
Muscle insulin sensitivity in postmenopausal women with overweight
In a 10-week double-blind trial in 25 postmenopausal women with prediabetes and overweight, 250 mg/day improved insulin-stimulated glucose uptake into muscle. Fasting glucose, insulin, body fat and liver fat did not change, and a pooled analysis of 8 trials found no significant effect on blood sugar or lipids.
Daytime drowsiness and fatigue in older adults
In a 12-week trial in 108 older Japanese adults, 250 mg/day taken in the afternoon gave the largest improvements in drowsiness and chair-stand time, but these measures also improved in the afternoon placebo group. In another trial, sleep quality improved over placebo after 12 weeks.
Aerobic capacity in recreational runners
In a 6-week double-blind trial in 48 runners who kept training, 600 or 1,200 mg/day raised oxygen uptake and power at the ventilatory thresholds more than placebo. VO2max and peak power did not change, and there were only 12 runners per group.
Mechanism of action
Raising NAD+
NMN is one enzyme step from NAD+. In a 14-day human comparison, NMN and nicotinamide riboside raised blood NAD to a similar degree, and lab work with human gut bacteria suggested part of the effect may run through conversion to nicotinic acid in the gut.
NAD+-dependent enzymes
NAD+ is used by enzymes such as sirtuins and PARPs that take part in energy metabolism and DNA repair in laboratory studies. Whether raising blood NAD with NMN changes these processes in people has not been shown.
Muscle insulin signalling
In the trial in women with prediabetes, NMN increased insulin signalling proteins and the expression of genes linked to muscle remodelling in muscle samples, alongside better muscle insulin sensitivity.
Clinical trials
60-day randomized double-blind placebo-controlled multicentre trial of placebo, 300, 600 or 900 mg/day. Three authors are employees of chemical companies. (Yi et al. 2023, Geroscience)
80 healthy middle-aged adults; all completed.
Blood NAD rose in all NMN groups, most at 600 and 900 mg. Six-minute walking distance increased more than with placebo, and SF-36 health scores were better. An algorithm-based blood aging score rose on placebo but not on NMN. HOMA-IR did not differ. No safety issues were found.
12-week randomized double-blind placebo-controlled trial of 250 mg/day. Three of the four authors are employees of Meiji, a food company. (Morifuji et al. 2024, Geroscience)
60 older adults.
The primary outcome, a stepping test, did not differ from placebo. 4-metre walking time was shorter and blood NAD higher than with placebo at 12 weeks, and sleep quality and daytime dysfunction scores were better. No adverse effects linked to NMN were seen.
12-week randomized double-blind placebo-controlled trial of 250 mg/day taken in the morning or afternoon. (Kim et al. 2022, Nutrients)
108 older Japanese adults in four groups.
Chair-stand time and drowsiness changed differently over time between groups. Afternoon NMN showed the largest effect sizes, but drowsiness also improved in the afternoon placebo group. No group differences were reported for sleep quality, grip strength or walking.
10-week randomized double-blind placebo-controlled trial of 250 mg/day with a hyperinsulinemic clamp. (Yoshino et al. 2021, Science)
25 postmenopausal women with prediabetes and overweight or obesity: 13 on NMN, 12 on placebo.
Insulin-stimulated glucose disposal and muscle insulin signalling increased with NMN but not placebo. Body composition, liver fat, blood pressure, fasting glucose, insulin and lipids did not change in either group. No adverse events were reported.
6-week randomized double-blind placebo-controlled trial of 300, 600 or 1,200 mg/day during training. (Liao et al. 2021, J Int Soc Sports Nutr)
48 recreational runners (10 men and 2 women per group).
Oxygen uptake and power at the first and second ventilatory thresholds rose more at 600 and 1,200 mg/day than with placebo. VO2max, O2-pulse and peak power did not change in any group.
14-day randomized open-label placebo-controlled trial comparing three NAD+ boosters. Most authors are employees of Nestlé. (Christen et al. 2026, Nat Metab)
65 healthy adults.
NMN and nicotinamide riboside, but not nicotinamide, raised blood NAD to a similar degree. No health outcome was measured.