NAD+, or nicotinamide adenine dinucleotide, is a coenzyme found in all living cells. It plays a crucial role in energy metabolism by helping convert food into energy. NAD+ is involved in redox reactions, which are essential for cellular respiration, allowing cells to produce ATP, the energy currency of the cell. In addition to its role in energy production, NAD+ is important for DNA repair and maintaining cellular health. It acts as a signaling molecule, influencing various biological processes, including aging and stress responses. Maintaining adequate levels of NAD+ is vital for overall health and well-being.