While the molecular weight of nicotinamide riboside is 255.25 g/mol,that of its chloride salt is 290.70 g/mol. As such, 100 mg of nicotinamide riboside chloride provides 88 mg of nicotinamide riboside. Recently, the crystal structure of a new series of crystalline forms of other nicotinamide riboside salts has been discovered. These salts correspond to different enantiomers of hydrogen tartrate and hydrogen malate and have a molecular weight of 404.33 and 388.33 g/mol respectively

     Nicotinamide riboside (NR) was first described in 1944 as a growth factor, termed Factor V, for Haemophilus influenza, a bacterium that lives in and depends on blood. Factor V, purified from blood, was shown to exist in three forms: NAD+, NMN and NR. NR was the compound that led to the most rapid growth of this bacterium.H. influenza cannot grow on nicotinic acid, nicotinamide, tryptophan or aspartic acid, which were the previously known precursors of NAD+.

In 2000, yeast Sir2 was shown to be an NAD+-dependent protein lysine deacetylase, which led several research groups to probe yeast NAD+ metabolism for genes and enzymes that might regulate lifespan.

       Different biosynthetic pathways are responsible for converting the different B3 vitamins into NAD+. The enzyme nicotinamide phosphoribosyltransferase (Nampt) catalyzes the rate-limiting step of the two-step pathway converting nicotinamide to NAD+. NR kinase enzymes can also function as a salvage pathway for NAD+, but this pathway is not essential