A 1 has demonstrated that NMN (nicotinamide mononucleotide), a precursor to the essential coenzyme NAD+, significantly improves muscle function in middle-aged and older adults. The results add to growing evidence that boosting NAD+ levels may counter some effects of aging.
The study, 1 in Cell Metabolism, randomized 80 participants aged 55-75 to receive either 250mg NMN daily or placebo for 12 weeks, with comprehensive assessments of muscle function, metabolism, and molecular markers.
The NAD+ Story
NAD+ is critical for cellular energy production, DNA repair, and hundreds of enzymatic reactions. Levels decline significantly with age—by age 60, NAD+ is roughly half what it was at age 20. This decline is implicated in mitochondrial dysfunction, impaired DNA repair capacity, reduced sirtuin activity, accumulation of cellular damage, and metabolic dysfunction.
Why NMN?
NAD+ itself cannot be taken orally—it does not survive digestion. NMN is a direct precursor that can be absorbed and converted to NAD+ in cells. Other precursors include nicotinamide riboside (NR), sold as Niagen. Animal studies showed NMN supplementation could restore NAD+ levels and reverse various aging phenotypes in mice. Human trials have been slower to emerge but are now producing results.
Trial Results
Participants receiving NMN showed significant improvements compared to placebo. Walking speed improved by 6.5% on the 30-meter walk test. Muscle strength increased in grip strength and leg press capacity. Aerobic capacity measured by VO2max improved by 3.5%. Insulin sensitivity showed better glucose handling in muscle tissue. Blood NAD+ metabolites increased by 38%. Effects were more pronounced in participants with lower baseline physical function, suggesting those who need it most may benefit most.
Mechanism Investigation
Muscle biopsies revealed molecular changes underlying the functional improvements: increased mitochondrial content per muscle fiber, enhanced expression of genes involved in energy metabolism, reduced markers of oxidative stress, and improved muscle satellite cell function important for regeneration.
Safety and Commercial Landscape
NMN was well-tolerated with no serious adverse events—only mild gastrointestinal symptoms in some participants that resolved with continued use. NMN supplements are widely available from brands including Elysium Health (using NR), ProHealth Longevity, DoNotAge, and ChromaDex. Prices range from $30 to over $200 per month.
Remaining Questions
Important unknowns include optimal dosing (studies have used 250mg to 1,200mg daily), whether NMN or NR is preferable, long-term effects of sustained NAD+ elevation, whether benefits extend beyond muscle, and interactions with exercise and diet. Larger, longer trials are underway to address these questions. For now, NMN appears to be a promising intervention for maintaining physical function with age.
