A systems-approach to NAD+ restoration.

A decline in NAD+ is a feature of ageing and may play a causal role in the process. NAD+ plays a pivotal role in myriad processes important in cellular metabolism and is a cosubstrate for enzymes that play key roles in pathways that modify ageing. Thus, interventions that increase NAD+ may slow aspects of the ageing trajectory and there is great interest in pharmacological NAD+ restoration. Dietary supplementation with NAD+ precursors, particularly nicotinamide riboside, has increased NAD+ levels in several human intervention studies and arguably been the most robust approach to date. However, consistency and reliability of such approaches to increase NAD+, and also impact on markers of efficacy to slow or reverse features of ageing, has been inconsistent. We argue that a major element of this variability may arise from the use of single-target approaches that do not consider the underlying biological complexity leading to NAD+ decline. Thus, a systems approach - targeting multiple key nodes in the NAD+ interactome - is likely to be more efficacious and reliable.