CoQ

Coenzyme Q, or CoQ, refers to a family of lipophilic quinones found in the mitochondria of aerobic organisms. In humans it exists predominantly as ubiquinone in its oxidized form and ubiquinol in its reduced form. CoQ is essential for mitochondrial energy production and also functions as an antioxidant.

In the inner mitochondrial membrane, CoQ participates in the electron transport chain, shuttling electrons from complexes I and II to complex III, and cycling between oxidized and reduced states to drive ATP synthesis. As ubiquinol, it scavenges reactive oxygen species and protects lipid membranes and LDL from lipid peroxidation.

CoQ is synthesized endogenously in human cells via the mevalonate pathway and requires several enzymes and nutrient cofactors; the molecule also occurs in dietary sources, with higher amounts in organ meats, fatty fish, and some vegetables. The most common human form is CoQ10, reflecting the length of the isoprenoid side chain.

Deficiency is uncommon but can occur in certain mitochondrial disorders or with long-term statin therapy, which may lower endogenous CoQ levels and contribute to myopathy. CoQ is available as a dietary supplement; evidence for improving energy, exercise performance, or cardiovascular outcomes is mixed and not conclusive. In heart failure, some trials report modest benefit, but guidelines do not universally endorse routine use. Large-scale, high-quality studies are still needed.

Safety: generally well tolerated; rare gastrointestinal upset and headaches. Potential interactions with anticoagulants such as warfarin have been reported, so monitoring is advised if CoQ supplementation is used with anticoagulation therapy.