What NMN is, what small human trials show about raising NAD+, doses studied, safety, how it compares with NR and NMNH, and how to judge an NMN product.
NMN (nicotinamide mononucleotide) is a form of vitamin B3 that the body converts into NAD+. Small, short placebo-controlled trials at 250 to 1,250 mg a day show it reliably raises NAD+ in blood, and it was well tolerated in those studies. Effects on health measures have been modest and mixed, several trials were funded by NMN makers, and no human study shows NMN slows aging.
NMN is a nucleotide the body uses to make NAD+, a coenzyme every cell needs for energy metabolism and for enzymes involved in DNA repair and cell signaling. It occurs naturally in small amounts in some foods, such as broccoli, avocado and edamame, but supplements provide far more. In September 2025 the FDA said NMN can be sold as a dietary supplement in the US.
NMN has a handful of placebo-controlled human trials, typically with about 10 to 110 people for 2 to 12 weeks, at 250 to 1,250 mg a day. They show NMN reliably raises blood NAD+. A few reported modest changes: a small US trial (Yoshino et al., 2021) in 25 postmenopausal women with prediabetes found 250 mg a day for 10 weeks improved muscle insulin sensitivity, and others reported changes in walking distance or grip strength. Results are mixed, several trials were funded by NMN ingredient makers, and none tested aging itself. Animal research suggests NAD+ falls with age, but how much that matters in people is still unclear.
NR (nicotinamide riboside) is a close cousin: both are forms of vitamin B3, and NR is one step further back in the chain that leads to NAD+. NR has more published human research, though much of it is company-funded and benefits beyond raising NAD+ are limited. No published trial has compared NMN and NR head to head in people.
NMNH is the reduced form of NMN. Cell and mouse studies suggest it raises NAD+ more strongly than NMN, but we found no peer-reviewed human trial, and no published data showing it is more stable. Human research on standard NMN doesn't automatically apply to NMNH.
NMN has been well tolerated at 250 to 2,000 mg a day in short trials, with side effects no more common than on placebo, but long-term safety is unknown. Talk to your doctor first if you are pregnant, being treated for cancer, or taking diabetes or blood pressure medicines. GenuinePurity Liposomal NMN, our top pick among NMN supplements, provides 500 mg per 2-capsule serving and comes with a 97-day guarantee (counted from delivery, with conditions); the product itself has not been tested in a trial.