This randomized, double-blind, placebo-controlled clinical trial evaluated the efficacy and safety of β-nicotinamide mononucleotide (NMN) supplementation across multiple centers in healthy middle-aged adults using dose-dependent treatment groups. The study assessed both safety outcomes and efficacy measures, with findings specific to how NMN supplementation affected the study population at varying doses. This evidence represents a human clinical trial, the highest level of evidence for establishing effects in human populations.