NMNH is reduced β-nicotinamide mononucleotide, which is a new nicotinamide adenine dinucleotide (NAD+) precursor, involves in electron transport in vivo, connects the tricarboxylic acid cycle and respiratory chain. Compared with NMN and NR, NMNH has better bioavailability and stronger NAD+ retention. Common salts of NMNH include disodium salt NMNH-2Na and calcium salt NMNH-Ca.