Coenzyme Q10 (ubiquinone) is an antioxidant that is also a cofactor for mitochondrial ATP generation. The levels of coenzyme Q10 seem to be lower in older people and in people with chronic diseases, such as cardiac problems, cancer, Parkinson's disease, diabetes, HIV/AIDS, and muscular dystrophies. However, it is not known whether these low levels contribute to these disorders.
Coenzyme Q10 is said to be useful because of its antioxidant effect and role in energy metabolism. Specific claims include an anticancer effect mediated by immune stimulation, decreased insulin requirements in patients with diabetes, slowed progression of Parkinson's disease, efficacy in treatment of heart failure, and protection against anthracycline cardiotoxicity. Although some preliminary studies suggest coenzyme Q10 may be useful in treating these disorders, results are unclear and more testing is needed.
Coenzyme Q10 may decrease response to warfarin. There are case reports of GI symptoms (eg, loss of appetite, abdominal pain, nausea, vomiting) and CNS symptoms (eg, dizziness, photophobia, irritability, headache). Other adverse effects include itching, rash, fatigue, and flu-like symptoms. Coenzyme Q10 is not recommended for people who exercise vigorously.
Last full review/revision May 2009 by Ara DerMarderosian, PhD