Nicotinamide adenine dinucleotide (NAD+) is a vital cofactor present in all  living cells, essential for a multitude of metabolic processes. It functions primarily as a carrier of electrons in redox reactions, crucial for the production and transfer of energy in cells. NAD+ is involved in key metabolic pathways such as glycolysis, the citric acid cycle, and oxidative phosphorylation. Beyond its metabolic roles, NAD+ is fundamental for DNA repair, cellular signaling, and gene expression regulation through its interaction with enzymes like sirtuins and poly (ADP-ribose) polymerases. The decline in NAD+ levels with age is associated with various age-related diseases, highlighting its potential in interventions aimed at enhancing health and longevity.