We've been searching for a fountain of youth for millennia. How can we not only live longer, but live healthier for longer? Nicotinamide adenine dinucleotide (NAD) is the latest anti-ageing candidate under the microscope. Norman and Tegan explain what it is, and whether supplements promising to boost NAD actually do what's advertised on the bottle. References: NAD+ metabolism and its roles in cellular processes during ageing NAD+ in Brain Aging and Neurodegenerative Disorders What is really known about the effects of nicotinamide riboside supplementation in humans Dietary Supplementation With NAD+-Boosting Compounds in Humans: Current Knowledge and Future Directions The use of a systems approach to increase NAD+ in human participants Specific ablation of Nampt in adult neural stem cells recapitulates their functional defects during aging