Feb 7, 2026NAD+ Biology: Age-Related Decline, PARP and CD38 Consumption, and Precursor InterventionsNAD+ declines 40-60% between young adulthood and old age due to increased consumption by PARP (DNA repair), CD38 (inflammatory enzyme), and reduced biosynthesis. This article explains the mechanisms, why precursor supplementation may help, and the current state of human evidence.