Nicotinamide mononucleotide (NMN) is a nucleotide derived from ribose and nicotinamide and serves as a direct precursor to NAD+ in the Preiss-Handler and salvage biosynthesis pathways. NMN is transported into cells via the Slc12a8 transporter and converted to NAD+ by NMNAT enzymes. Research into NMN has grown substantially alongside interest in NAD+ biology, with preclinical studies in aged animal models demonstrating improvements in energy metabolism, insulin sensitivity, muscle function, and cognitive performance following NMN supplementation. It is considered a key compound in translational aging research.