NAD+ precursors like NMN and NR are effective in increasing NAD+ levels in mice but show limited efficacy in humans. The discussion highlights the challenges in translating these findings from animal models to human physiology, particularly regarding the mechanisms that regulate NAD+ levels in humans. Factors that prevent significant increases in NAD+ include differences in metabolism and cellular uptake of these precursors. Research indicates that while various strategies to boost NAD+ have demonstrated benefits in preclinical studies, the translation to human health remains complex. The referenced study reviews NAD+ biochemistry and its implications for health and disease, emphasizing the ongoing exploration of NAD+ boosters for enhancing healthspan and lifespan.