nmn

Nicotinamide mononucleotide (NMN) is a nucleotide that serves as a direct precursor to nicotinamide adenine dinucleotide (NAD+), a central cofactor in cellular metabolism. In mammalian cells, NMN is produced via salvage pathways and is converted to NAD+ by the enzyme NMN adenylyltransferase (NMNAT). NMN is present in trace amounts in some foods, but dietary intake is typically not sufficient to meaningfully raise NAD+ levels.

Biological significance and pathways: NAD+ participates in redox reactions and acts as a substrate for enzymes such as sirtuins, PARPs, and CD38. Age-related declines in NAD+ have been observed in various tissues, prompting interest in NAD+ precursors like NMN as potential interventions to support cellular energy and genomic maintenance. NMN can be formed from nicotinamide riboside (NR) via NR kinase (NRK) or from nicotinamide in salvage pathways, and is then converted to NAD+ by NMNATs.

Clinical evidence and research status: In animal studies, NMN supplementation has been associated with improvements in mitochondrial function, insulin sensitivity, and some markers related to aging. In humans, evidence is limited and primarily concerns short-term increases in NAD+ levels and modest metabolic effects; large, well-controlled trials assessing aging-related outcomes are not yet available. The overall clinical significance of NMN for aging or disease prevention remains unproven.

Safety and regulatory considerations: Short-term use in healthy adults appears generally well tolerated, but long-term safety data are lacking. Potential risks and interactions, particularly in cancer and comorbid conditions, are not fully understood. In many regions, NMN supplements are sold as dietary supplements rather than prescription therapies, with product quality and regulatory oversight varying by jurisdiction.