This post hoc analysis of a randomized, double-blinded, placebo-controlled human clinical trial examined the relationship between blood NAD+ levels and various laboratory parameters in middle-aged healthy individuals, both at baseline and following nicotinamide mononucleotide (NMN) supplementation. The study identified associations between NAD+ levels and specific blood biomarkers, with changes occurring after NMN supplementation in this population. **Evidence level: Human clinical trial**