Coenzyme Q10

Topic Overview

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 failure

If 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.^{footnote 1}

Cancer

In 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.

But the National Cancer Institute (NCI) rates the strength of the evidence for CoQ10 and cancer as weak.^{footnote 2}

Other claims

Research does not support a helpful effect of CoQ10 in periodontal (gum) disease, muscular dystrophy, or exercise recovery.

Is CoQ10 safe?

Taking 100 mg a day or more of CoQ10 has caused mild insomnia in some people. And research has detected elevated levels of liver enzymes in people taking doses of 300 mg per day for long periods of time. Liver toxicity has not been reported.

Other reported side effects include rashes, nausea, upper abdominal pain, dizziness, sensitivity to light, irritability, headache, heartburn, and fatigue.

Medicines for high cholesterol (statins) and medicines that lower blood sugar cause a decrease of CoQ10 levels and reduce the effects of CoQ10 supplements. CoQ10 can reduce the body's response to the blood thinner (anticoagulant) medicine warfarin (Coumadin) and can decrease insulin requirements in people with diabetes.

The U.S. Food and Drug Administration (FDA) does not regulate dietary supplements in the same way it regulates medicines. A dietary supplement can be sold with limited or no research on how well it works or on its safety.

Always tell your doctor if you are using a dietary supplement or if you are thinking about combining a dietary supplement with your conventional medical treatment. It may not be safe to forgo your conventional medical treatment and rely only on a dietary supplement. This is especially important for women who are pregnant or breastfeeding.

When using dietary supplements, keep in mind the following:

• Like conventional medicines, dietary supplements may cause side effects, trigger allergic reactions, or interact with prescription and nonprescription medicines or other supplements you might be taking. A side effect or interaction with another medicine or supplement may make other health conditions worse. Always tell your doctor or pharmacist about all dietary supplements you are taking.
• The way dietary supplements are manufactured may not be standardized. Because of this, how well they work or any side effects they cause may differ among brands or even within different lots of the same brand. The form of supplement that you buy in health food or grocery stores may not be the same as the form used in research.
• Other than for vitamins and minerals, the long-term effects of most dietary supplements are not known.