NR (Nicotinamide Riboside)

NR (Nicotinamide Riboside) is a form of vitamin B3 (niacin) and an established oral NAD+ precursor. It is present in trace amounts in milk and certain foods. NR enters the NAD+ biosynthesis pathway via nicotinamide riboside kinases (NRK1 and NRK2), which phosphorylate NR to NMN, which is then converted to NAD+ by NMNAT enzymes.

NR was identified as a bioavailable NAD+ precursor in a landmark 2004 study (Bieganowski and Brenner, Cell), and its ability to raise blood NAD+ in humans was first confirmed in 2016 (Trammell et al., Nature Communications). Since then, it has become one of the most studied longevity compounds in human clinical trials.

The commercial NR product Tru Niagen (ChromaDex) has been through multiple peer-reviewed RCTs including CAMINO (300 vs 1000 mg/day), showing dose-dependent NAD+ elevation in whole blood, with the 1000 mg dose achieving approximately 90% increase from baseline.

Like NMN, the therapeutic rationale for NR supplementation rests on the well-documented decline in tissue NAD+ with aging, the critical roles of NAD+ in sirtuin activation (particularly SIRT1, SIRT3, SIRT5), PARP-mediated DNA repair, and mitochondrial energy metabolism (Complex I requires NAD+).

NR vs NMN differences include: NR requires two enzymatic steps to become NAD+ (vs NMN's one step); NR may have better tissue distribution in certain cell types (particularly liver and neurons via NRK1); NMN may be more efficient in skeletal muscle. Both reliably elevate circulating NAD+ metabolites.

Research applications include neurodegenerative disease (mouse models of ALS, Alzheimer's, and Parkinson's), cardiovascular aging, metabolic syndrome, exercise physiology, and healthy aging protocols.