NADH

NADH is the reduced form of NAD+, generated when NAD+ accepts electrons during glycolysis, the citric acid cycle, and fatty acid oxidation. It delivers electrons to the mitochondrial electron transport chain, driving ATP synthesis. The cellular NAD+/NADH ratio reflects metabolic state and influences sirtuin activity, redox signaling, and substrate selection. A shifted ratio toward NADH, often observed in aging and metabolic disease, is associated with reductive stress and mitochondrial dysfunction.