What is coenzyme Q10?Coenzyme Q10 (CoQ10) is a substance similar to a vitamin. It is found in every cell of the body. Your body makes CoQ10, and your cells use it to produce energy your body needs for cell growth and maintenance. It also functions as an antioxidant, which protects the body from damage caused by harmful molecules. CoQ10 is naturally present in small amounts in a wide variety of foods, but levels are particularly high in organ meats such as heart, liver, and kidney, as well as beef, soy oil, sardines, mackerel, and peanuts. Coenzymes help enzymes work to digest food and perform other body processes, and they help protect the heart and skeletal muscles. CoQ10 is available in the United States as a dietary supplement. It is also known as Q10, vitamin Q10, ubiquinone, or ubidecarenone.What is CoQ10 used for?Many claims are made about CoQ10. It is said to help heart failure, as well as cancer, muscular dystrophy, and periodontal disease. It is also said to boost energy and speed recovery from exercise. Some people take it to help reduce the effects certain medicines can have on the heart, muscles, and other organs.Heart failureIf you have heart failure, talk to your doctor before you take any supplement. There's no strong evidence that vitamins or other supplements can help treat heart failure. They are used along with medical heart failure treatments, not instead of treatment.But you may still hear about CoQ10 supplements and heart failure. CoQ10 has not been shown definitely to relieve heart failure symptoms. Only some of the studies of coenzyme Q10 showed that it helps heart failure symptoms.1CancerIn 1961, scientists saw that people with cancer had little CoQ10 in their blood. They found low CoQ10 blood levels in people with myeloma, lymphoma, and cancers of the breast, lung, prostate, pancreas, colon, kidney, and head and neck. Some research has suggested that CoQ10 helps the immune system and may be useful as a secondary treatment for cancer.CoQ10 may keep the antitumor drug doxorubicin from hurting the heart. Three studies examined the use of CoQ10 along with conventional treatment for cancer. The three studies contained a total of 41 women with breast cancer. In each study, the women improved. This fat-soluble substance, which resembles a vitamin, is present in most eukaryotic cells, primarily in the mitochondria. It is a component of the electron transport chain and participates in aerobic cellular respiration, which generates energy in the form of ATP. Ninety-five percent of the human body's energy is generated this way. Therefore, those organs with the highest energy requirements—such as the heart, liver, and kidney—have the highest CoQ10 concentrations.Deficiency and toxicity There are two major factors that lead to deficiency of CoQ10 in humans: reduced biosynthesis, and increased use by the body. Biosynthesis is the major source of CoQ10. Biosynthesis requires at least 12 genes, and mutations in many of them cause CoQ deficiency. CoQ10 levels also may be affected by other genetic defects (such as mutations of mitochondrial DNA, ETFDH, APTX, FXN, and BRAF, genes that are not directly related to the CoQ10 biosynthetic process). The role of statins in deficiencies is controversial. Some chronic disease conditions (cancer, heart disease, etc.) also are thought to reduce the biosynthesis of and increase the demand for CoQ10 in the body, but there are no definite data to support these claims. Usually, toxicity is not observed with high doses of CoQ10. A daily dosage up to 3600 mg was found to be tolerated by healthy as well as unhealthy persons. Some adverse effects, however, largely gastrointestinal, are reported with very high intakes. The observed safe level (OSL) risk assessment method indicated that the evidence of safety is strong at intakes up to 1200 mg/day, and this level is identified as the OSL.