What small human trials of NMN found: reliable rises in blood NAD+, mixed results for anything else, the doses tested, safety unknowns and what to expect.
Partly. In small, short human trials at 250 to 1,250 mg a day, NMN reliably raised blood NAD+ levels. A few trials reported modest changes in muscle insulin sensitivity, walking distance or grip strength, but results are mixed, several trials were funded by NMN makers, and no human study shows NMN slows aging.
NMN (nicotinamide mononucleotide) is a form of vitamin B3 that the body converts into NAD+, a molecule involved in energy metabolism and cell repair. NAD+ levels are thought to fall with age, which is the idea behind NMN supplements. Human trials so far have been small (about 10 to 110 people) and short (2 to 12 weeks).
One of the best-known, a 2021 Washington University trial (Yoshino et al.), gave 25 postmenopausal women with prediabetes 250 mg a day for 10 weeks and reported improved muscle insulin sensitivity. Other trials in healthy middle-aged and older adults found higher blood NAD+ and, in some cases, small changes in walking speed or grip strength, while other measures did not change.
NMN has been well tolerated at 250 to 2,000 mg a day in trials lasting up to about three months, with side effects no more common than on placebo. Nobody has published results on people taking NMN for a year or more. People who are pregnant, breastfeeding, under 18, being treated for cancer or have a history of it, or taking diabetes or blood pressure medicines should talk to their doctor first.
GenuinePurity NMN is our top pick among NMN supplements. It provides 500 mg of NMN per 2-capsule serving, a dose in the range used in trials, and has a 97-day guarantee with conditions. The product itself hasn't been tested, its "liposomal" absorption claim is unproven, and its $19 trial offer auto-renews at $49 a month.