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.