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.