Coenzyme Q10 (CoQ10), also known as ubiquinol (reduced form) or ubiquinone (oxidised form), is a fat-soluble compound found in virtually every cell in the body. It is essential for mitochondrial energy production, serving as a critical electron carrier in the inner mitochondrial membrane where it helps generate ATP, the cell's primary energy currency. CoQ10 is also a potent antioxidant, protecting cell membranes and mitochondrial DNA from oxidative damage.

The body produces CoQ10 naturally, but production declines with age from around the fourth decade. CoQ10 is also depleted by statin medications, which block the same biochemical pathway (the mevalonate pathway) used to synthesise both cholesterol and CoQ10. Dietary sources include organ meats, oily fish, and nuts, but dietary intake alone provides only a small proportion of the body's needs relative to endogenous synthesis.