Fingerstick blood assay maps real-world NAD + disparity across gender and age.

Nicotinamide adenine dinucleotide (NAD + ) level has been associated with various age-related diseases and its pharmacological modulation emerges as a potential approach for aging intervention. But human NAD + landscape exhibits large heterogeneity. The lack of rapid, low-cost assays limits the establishment of whole-blood NAD + baseline and the development of personalized therapies, especially for those with poor responses towards conventional NAD + supplementations. Here, we developed an automated NAD + analyzer for the rapid measurement of NAD + with 5 μL of capillary blood using recombinant bioluminescent sensor protein and automated optical reader. The minimal invasiveness of the assay allowed a frequent and decentralized mapping of real-world NAD + dynamics. We showed that aerobic sport and NMN supplementation increased whole-blood NAD + and that male on average has higher NAD + than female before the age of 50. We further revealed the long-term stability of human NAD + baseline over 100 days and identified major real-world NAD + -modulating behaviors.