Evidence Level
Nicotinamide Riboside (NR) is a well-researched NAD+ precursor with established safety and efficacy in humans. Martens et al. (2018) demonstrated that 1000mg of NR daily for six weeks safely elevated NAD+ levels by approximately 60% in healthy older adults, confirming its tolerability and bioavailability. Subsequent studies have expanded on these findings: Elhassan et al. (2019) showed that NR increases NAD+ in skeletal muscle while reducing inflammation, suggesting potential anti-aging benefits. Trammell et al. (2016) further characterized the pharmacokinetics of oral NR, confirming its bioavailability in humans.
Recent research has explored NR's effects in various clinical contexts. Shoji et al. (2025) conducted a double-blind randomized crossover trial in patients with Werner syndrome, finding that NR supplementation improved arterial stiffness and reduced skin ulcer area over 26 weeks. However, Thomas et al. (2026) reported mixed results in a Phase 2 study, where NR failed to prevent axon degeneration or promote nerve regeneration. These findings underscore the need for further investigation into NR's therapeutic applications.
Gallagher and Emmanuel (2026) conducted a systematic review of 113 studies, concluding that while NAD+ supplementation improves metabolic function in rodents, human healthspan outcomes remain inconsistent. This highlights the importance of continued research to better understand NR's role in human aging and disease prevention.