Nicotinamide Adenine Dinucleotide (NAD+) is a vital electron transporter, coenzyme, and signaling molecule found in all cells. Its reduced form (NADH) and phosphorylated forms (NADP+ and NADPH) are crucial for cellular processes, including glycolysis, the Krebs cycle, and the electron transport chain. NADP+ and NADPH support anabolic processes such as cholesterol and nucleic acid production, fatty acid elongation, and antioxidant regeneration. NAD+ also acts as a precursor for cyclic ADP ribose, important for calcium signaling.

The body produces NAD+ using tryptophan and vitamin B3 (niacin), and it can also be synthesized from intermediates like nicotinamide mononucleotide. NAD+ levels are highest in neonates and decline with age, often halving by age 50. This drop is linked to increased levels of CD38, which degrades NAD+, and factors like oxidative stress and inflammation.

The loss of NAD+ with aging is associated with various age-related diseases, including diabetes, heart disease, and Alzheimer's. NAD+ was recognized as essential for treating pellagra in the early 1900s, and NAD+ IV infusion has been used for addiction treatment since the 1960s. Although its safety and efficacy for addiction need further clinical evaluation, NAD+-replacement therapy may improve mitochondrial function, genomic stability, neuroprotection, and longevity. Many recent clinical trials are underway to explore these potential benefits.