Emerging strategies, applications and challenges of targeting NAD in the clinic.

Beyond their classical functions as redox cofactors, recent fundamental and clinical research has expanded our understanding of the diverse roles of nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) in signaling pathways, epigenetic regulation and energy homeostasis. Moreover, NAD and NADP influence numerous diseases as well as the processes of aging, and are emerging as targets for clinical intervention. Here, we summarize safety, bioavailability and efficacy data from NAD-related clinical trials, focusing on aging and neurodegenerative diseases. We discuss the established NAD precursors nicotinic acid and nicotinamide, newer compounds such as nicotinamide riboside and nicotinamide mononucleotide, and emerging precursors. We also discuss technological advances including in industrial-scale production and real-time detection, which are facilitating NAD research and clinical translation. Finally, we emphasize the need for further large-scale studies to determine optimal dose, administration routes and frequency, as well as long-term safety and interindividual variability in response.