Evidence Level
Moderate
NR has the most robust human safety dataset of any NAD+ precursor. Martens et al. (2018) published a landmark crossover RCT showing 1000mg NR daily safely elevated NAD+ by ~60% in healthy older adults. Elhassan et al. (2019) confirmed NAD+ elevation in skeletal muscle and demonstrated anti-inflammatory effects. Trammell et al. (2016) established the pharmacokinetics of oral NR in humans. ChromaDex's Niagen has received FDA GRAS (Generally Recognized as Safe) status and two FDA new dietary ingredient notifications. The NR vs NMN debate remains active — NR has more published human data, while NMN is one enzymatic step closer to NAD+.