NADH is primarily produced during glycolysis, the citric acid cycle (also known as the Krebs cycle), and the malate-aspartate shuttle. During glycolysis, glucose is broken down into pyruvate, yielding two molecules of NADH. In the citric acid cycle, acetyl-CoA is oxidized, producing three molecules of NADH per cycle. The malate-aspartate shuttle helps transfer electrons from NADH in the cytosol to NADH in the mitochondria, facilitating oxidative phosphorylation.
