This review article examines the relationship between aging, homeostasis disruption, and age-associated diseases, with a focus on nicotinamide mononucleotide (NMN) as a potential clinical application (evidence level: review). The authors discuss how aging affects the body’s ability to maintain homeostasis and how this contributes to the development of chronic diseases, while exploring NMN’s proposed mechanisms in potentially addressing age-related physiological decline. The review synthesizes existing literature on NMN’s role in cellular energy metabolism and NAD+ restoration as it relates to aging and disease management.