The NAD+ Pathway
NAD+ (Nicotinamide Adenine Dinucleotide) is the end product — the active coenzyme your cells use. NMN (Nicotinamide Mononucleotide) and NR (Nicotinamide Riboside) are precursors that your body converts into NAD+. Think of NAD+ as the destination and NMN/NR as two different roads to get there. You can also supplement NAD+ directly, but it has poor oral bioavailability — most is broken down before reaching cells.
What Does the Research Say?
NMN and NR have the strongest human trial evidence for raising blood NAD+ levels — both work. A landmark 2021 Science study showed NMN increased NAD+ levels in skeletal muscle of premenopausal women and improved insulin sensitivity. A 2022 Cell Reports Medicine study showed NMN improved aerobic capacity in amateur runners. NR has been shown in multiple trials to raise whole blood NAD+ levels safely.
NMN vs NR: Which Is Better?
Both raise NAD+ levels, but the question of which raises levels more effectively in which tissues remains actively debated. NMN appears to have better cellular uptake through a specific transporter (Slc12a8 — discovered in mouse studies). NR is older, has more published human trial data, and is cheaper. For most people starting longevity protocols, NR is a reasonable starting point given its established safety and efficacy profile.