Precursors like nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR) take slightly different paths into and inside cells to boost NAD+ levels.
Various molecules, all differing by a few atoms, get passed along and transformed by different receptors and enzymes inside and outside cells to create the vital molecule nicotinamide adenine dinucleotide (NAD+). But these distinct NAD+ precursors, whose differences in atomic structures can be distinguished by just a letter in their formula or a word in their chemical name, are not all created equal.
Research shows that drinking water or eating food laden with these metabolic intermediaries or through supplements, whether consumed or injected, even if they all participate in the same pathway, do not have the same effect on NAD+ levels and cell, tissue, and body health and function. Part of their required dose and effectiveness may depend on how these NAD+ precursors get transformed by different enzymes and whether they can get into cells.