Definition: NAD+ is a universal electron carrier and enzymatic cofactor found in every living cell. It is the "currency of metabolism," essential for converting nutrients into energy (ATP) and acting as a consumed fuel for longevity proteins.
The Aging Crisis: NAD+ levels decline by up to 50% between young adulthood and old age. This collapse is a primary driver of mitochondrial dysfunction, genomic instability, and cellular senescence.[1]
Biological Role:
Intervention Strategy: NAD+ itself has poor oral bioavailability and cannot easily cross cell membranes. Clinical strategies focus on precursors (like NMN and NR) that the cell can convert into NAD+.
👉 For intervention protocols, dosage, and supplements, see NAD+ Precursors.
NAD+ exists in two distinct forms, and the ratio between them determines the metabolic state of the cell.
In its primary role, NAD+ acts as an electron shuttle. It accepts high-energy electrons from the breakdown of glucose and fatty acids to become NADH (reduced form). It then donates these electrons to the Electron Transport Chain in the mitochondria to generate ATP.
In its secondary role—critical for aging—NAD+ is permanently consumed by enzymes. It is broken down to power reactions that repair DNA and regulate gene expression.
NAD+ is the obligate substrate for three major classes of enzymes involved in the Hallmarks of Aging.
Sirtuins (SIRT1–SIRT7) are a family of deacylases that require NAD+ to function. They cannot operate without it.
Poly-ADP-ribose polymerases (PARPs), particularly PARP1, are the "first responders" to DNA damage.