What it is
Nicotinamide riboside is an NAD+ precursor vitamin. The Martens trial studied supplementation as a way to alter NAD+ metabolism in humans. That question is narrower than whether a supplement prevents disease or slows aging.
What human trials actually show
- Study
- Martens et al., 2018
- Who took part
- Healthy middle-aged and older adults.
- Design
- Randomised, double-blind, placebo-controlled crossover trial with two six-week periods.
- Reported result
- NR stimulated NAD+ metabolism and was well tolerated during the study.
- What remained open
- The authors called for further trials of possible blood-pressure and arterial-stiffness benefits. The abstract does not establish prevention of cardiovascular disease.
What the wider review found
A 2026 systematic review included 33 human intervention studies and 80 rodent studies from January 2010 to October 2025. Oral NR and NMN showed biochemical activity, while health-related outcomes in people were mixed or endpoint-specific. The review judged anti-aging and wellness effectiveness inconclusive. Tolerability observed over weeks or months should not be presented as a guarantee of long-term safety.
Compare NR with NMN or an NAD infusion
Use the NMN vs NR study comparison for differences in populations and endpoints. An oral precursor and an infusion of NAD+ itself are different interventions: the oral-versus-IV comparison separates the evidence by route.
Questions and answers
What did the 2018 NR trial find?
In healthy middle-aged and older adults, NR stimulated NAD+ metabolism and was well tolerated during two six-week crossover periods. This does not establish the same result for every population or product.
Does this prove that NR extends life?
No. The trial investigated NAD+ metabolism and physiological measures, not human lifespan. The 2026 review judged clinical anti-aging and wellness effectiveness inconclusive.
NR or NMN?
Regulatory status is not an efficacy comparison. Our NMN-versus-NR comparison separates the populations, durations and endpoints of selected human studies rather than declaring a winner.