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Coenzyme Q10

This complementary and alternative medicine (CAM) information provides an overview of the use of coenzyme Q10 in cancer therapy. The summary includes a history of coenzyme Q10 research, a review of laboratory studies, and data from investigations involving human subjects. Although several naturally occurring forms of coenzyme Q have been identified, Q10 is the predominant form found in humans and most mammals, and it is the form most studied for therapeutic potential.

Coenzyme Q10 is made naturally by the human body.
Coenzyme Q10 helps cells to produce energy, and it acts as an antioxidant.
Coenzyme Q10 has shown an ability to stimulate the immune system and to protect the heart from damage caused by certain chemotherapy drugs.
Low blood levels of coenzyme Q10 have been detected in patients with some types of cancer.
No report of a randomized clinical trial of coenzyme Q10 as a treatment for cancer has been published in a peer-reviewed, scientific journal.
Coenzyme Q10 is marketed in the United States as a dietary supplement.

Coenzyme Q10: Questions and Answers

Complementary and alternative medicine (CAM)—also referred to as integrative medicine—includes a broad range of healing philosophies, approaches, and therapies. A therapy is generally called complementary when it is used in addition to conventional treatments; it is often called alternative when it is used instead of conventional treatment. (Conventional treatments are those that are widely accepted and practiced by the mainstream medical community.) Depending on how they are used, some therapies can be considered either complementary or alternative. Complementary and alternative therapies are used in an effort to prevent illness, reduce stress, prevent or reduce side effects and symptoms, or control or cure disease.

Unlike conventional treatments for cancer, complementary and alternative therapies are often not covered by insurance companies. Patients should check with their insurance provider to find out about coverage for complementary and alternative therapies.

Cancer patients considering complementary and alternative therapies should discuss this decision with their doctor or nurse, as they would any therapeutic approach, because some complementary and alternative therapies may interfere with their standard treatment or may be harmful when used with conventional treatment.

  1. What is Coenzyme Q10?

    Coenzyme Q10 (also known as CoQ10, Q10, vitamin Q10, ubiquinone, or ubidecarenone) is a compound that is made naturally in the body. A coenzyme is a substance needed for the proper functioning of an enzyme, a protein that speeds up the rate at which chemical reactions take place in the body. The Q and the 10 in coenzyme Q10 refer to parts of the compound’s chemical structure.

    Coenzyme Q10 is used by cells to produce energy needed for cell growth and maintenance. It is also used by the body as an antioxidant. An antioxidant is a substance that protects cells from chemicals called free radicals. Free radicals are highly reactive chemicals that can damage important parts of cells, including deoxyribonucleic acid (DNA). (DNA is a molecule inside cells that carries genetic information and passes it from one generation to the next.) This damage may play a role in the development of cancer.

    Coenzyme Q10 is found in most body tissues. The highest amounts are found in the heart, liver, kidneys, and pancreas. The lowest amounts are found in the lungs. Tissue levels of coenzyme Q10 decrease as people get older.

  2. What is the history of the discovery and use of coenzyme Q10 as a complementary or alternative treatment for cancer?

    Coenzyme Q10 was first identified in 1957. Its chemical structure was determined in 1958. Interest in coenzyme Q10 as a potential treatment for cancer began in 1961, when a deficiency of the enzyme was noted in the blood of cancer patients. Low blood levels of coenzyme Q10 have been found in patients with myeloma, lymphoma, and cancers of the breast, lung, prostate, pancreas, colon, kidney, and head and neck.

    Studies have yielded information about how coenzyme Q10 works in the body to produce energy and act as an antioxidant. Some studies have suggested that coenzyme Q10 stimulates the immune system and increases resistance to disease. In part because of this, researchers have theorized that coenzyme Q10 may be useful as an adjuvant therapy for cancer. (Adjuvant therapy is treatment given following the primary treatment to enhance the effectiveness of the primary treatment.)

  3. How is coenzyme Q10 administered?

    Coenzyme Q10 is usually taken by mouth as a pill (tablet or capsule). It may also be given by injection into a vein (IV). In animal studies, coenzyme Q10 is given by injection.

  4. Have any preclinical (laboratory and animal) studies been conducted using coenzyme Q10?

    Laboratory studies of coenzyme Q10 have focused on describing its chemical structure and how it works in the body. Animal studies have found that coenzyme Q10 stimulated the immune system and increased resistance to disease. Coenzyme Q10 helped to protect the hearts of animals given the anticancer drug doxorubicin, which can cause damage to the heart muscle.

  5. Have any clinical trials (research studies in humans) been conducted with  coenzyme Q10?

    The promising results from animal studies of coenzyme Q10 and the anticancer drug doxorubicin led researchers to test coenzyme Q10 in a randomized clinical trial with 20 patients. (A randomized clinical trial is a study in which the participants are assigned by chance to separate groups that compare different treatments; neither the researchers nor the participants can choose which group.) The researchers examined whether coenzyme Q10 would protect the heart from the damage caused by doxorubicin. The results of this trial and others have confirmed that coenzyme Q10 decreases the effects of doxorubicin on the heart. However, no report of a randomized clinical trial of coenzyme Q10 as a treatment for cancer has been published in a peer-reviewed, scientific journal.

  6. Have other studies of coenzyme Q10 been conducted in people?

    Three other small studies were conducted using coenzyme Q10 as a dietary supplement in patients undergoing conventional cancer treatment. In these studies, the researchers explored the potential use of coenzyme Q10 as an adjuvant therapy for cancer.

    • The first study, which was conducted in Denmark, involved 32 breast cancer patients. All of the participants received coenzyme Q10 and several other dietary supplements, in addition to their standard treatment. Six of the patients were reported to show some signs of remission (disappearance of the signs and symptoms of cancer). However, the data were not complete, and information that suggested remission was presented for only three of the six patients. All of the participants reported decreased use of painkillers, improved quality of life, and absence of weight loss during treatment.

    • In a followup study, one new patient and one of the patients who had a reported remission were treated with high doses of coenzyme Q10 for 3 to 4 months. Both of the patients had breast cancer remaining after surgery. After the period of high-dose coenzyme Q10 supplementation, both patients appeared to experience complete regression (decrease in the size or extent) of their remaining cancer. However, it is not known which of the six patients with a reported remission in the first study took part in the followup study.

    • In a third study conducted by the same researchers, three breast cancer patients were given high-dose coenzyme Q10 and followed for 3 to 5 years. One patient had complete remission of cancer that had spread to the liver, another had remission of cancer that had spread to the chest wall, and the third had no evidence of breast cancer remaining after surgery.

    It is important to note that problems with the design of these studies may have influenced their results. For example, the studies did not have control groups (all patients received coenzyme Q10), and there may have been differences in the characteristics of patients who were selected for the followup study and those who were not. Other factors that may have affected the results include the following:  the participants received a variety of supplements in addition to coenzyme Q10, and they received standard treatment either during or just before coenzyme Q10 supplementation. Therefore, it is impossible to determine whether any of the beneficial results was directly related to coenzyme Q10 therapy.

    There have also been anecdotal reports that coenzyme Q10 has increased the survival of patients with cancers of the pancreas, lung, colon, rectum, and prostate. (Anecdotal reports are incomplete descriptions of the medical and treatment history of one or more patients.) The patients described in these reports also received treatments other than coenzyme Q10, including chemotherapy, radiation therapy, and surgery.

  7. Have any side effects or risks been reported from coenzyme Q10?

    No serious side effects have been reported from the use of coenzyme Q10. Some patients using coenzyme Q10 have experienced mild insomnia (inability to sleep), elevated levels of liver enzymes, rashes, nausea, and upper abdominal pain. Other reported side effects have included dizziness, visual sensitivity to light, irritability, headache, heartburn, and fatigue.

    Patients should talk with their health care provider about possible interactions between coenzyme Q10 and prescription drugs they may be taking. Certain drugs, such as those that are used to lower cholesterol or blood sugar levels, may reduce the effects of coenzyme Q10. Coenzyme Q10 may also alter the body’s response to warfarin (a drug that prevents the blood from clotting) and insulin.

  8. Are there any other potential drawbacks to taking coenzyme Q10?

    As noted in question 1, coenzyme Q10 is used by the body as an antioxidant. Antioxidants protect cells from free radicals, which are highly reactive chemicals that can damage cells. Some conventional cancer therapies, such as anticancer drugs and radiation treatment, kill cancer cells in part by causing free radicals to form. Researchers are studying whether using coenzyme Q10 along with conventional therapies is positive (i.e., does not interfere with the effects of the conventional therapies, or increases the therapies’ beneficial effects on cancer cells while protecting normal cells) or negative (i.e., interferes with the therapeutic effects).

  9. Has the Food and Drug Administration (FDA) approved coenzyme Q10 for use in the United States?

    Several companies distribute coenzyme Q10 as a dietary supplement. In the United States, dietary supplements are regulated as foods, not drugs. This means that evaluation and approval by the FDA are not required before marketing, unless specific health claims are made about the supplement. It should be noted that, because dietary supplements are not formally reviewed for manufacturing consistency, there may be variation in the composition of the supplement from one batch to another.

    Also, to conduct clinical drug research with humans in the United States, researchers must file an Investigational New Drug (IND) application with the FDA. Because an IND application is highly confidential, it is not known whether one has been submitted or approved for the study of coenzyme Q10 as a treatment for cancer.

  10. When considering complementary and alternative therapies, what questions should patients ask their health care provider?

    • What benefits can be expected from this therapy?
    • What are the risks associated with this therapy?
    • Do the known benefits outweigh the risks?
    • What side effects can be expected?
    • Will the therapy interfere with conventional treatment?
    • Is this therapy part of a clinical trial? If so, who is sponsoring the trial?
    • Will the therapy be covered by health insurance?

  11. How are complementary and alternative approaches evaluated?

    It is important that the same scientific evaluation which is used to assess conventional approaches be used to evaluate complementary and alternative therapies. A number of medical centers are evaluating complementary and alternative therapies by developing clinical trials to test them.

    More information about how CAM approaches are evaluated can be found in the National Cancer Institute (NCI) fact sheet Complementary and Alternative Medicine in Cancer Treatment: Questions and Answers. This fact sheet can be accessed at on the Internet, or by calling the Cancer Information Service (CIS) at 1–800–422–6237.

  12. How can patients and their health care providers learn more about complementary and alternative therapies?

    Patients and their doctor or nurse can learn about complementary and alternative therapies from the following Government agencies:

    The National Center for Complementary and Alternative Medicine (NCCAM) at the National Institutes of Health (NIH) facilitates research and evaluation of complementary and alternative practices, and provides information about a variety of approaches to health professionals and the public.

NCCAM Clearinghouse
Post Office Box 7923
Gaithersburg, MD 20898–7923
Telephone: 1–888–644–6226 (toll free)
301–519–3153 (for International callers)
TTY (for deaf and hard of hearing callers): 1–866–464–3615
Fax: 1–866–464–3616
Web site:

NCCAM and the NIH National Library of Medicine (NLM) jointly developed CAM on PubMed, a free and easy-to-use search tool for finding CAM-related journal citations. As a subset of the NLM's PubMed bibliographic database, CAM on PubMed features more than 230,000 references and abstracts for CAM-related articles from scientific journals. This database also provides links to the Web sites of over 1,800 journals, allowing users to view articles in full-text. (A subscription or other fee may be required to access full-text articles.) CAM on PubMed is available through the NCCAM Web site at It can also be accessed at by selecting "Limits" and choosing "Complementary Medicine" as a subset.

The NCI Office of Cancer Complementary and Alternative Medicine (OCCAM) coordinates the activities of the NCI in the area of complementary and alternative medicine (CAM). OCCAM supports CAM cancer research and provides information about cancer-related CAM to health providers and the general public via its Web site on the Internet.

The Food and Drug Administration (FDA) regulates drugs and medical devices to ensure that they are safe and effective.

Food and Drug Administration
5600 Fishers Lane
Rockville, MD 20857
Telephone: 1–888–463–6332 (toll free)
Web site:

The Federal Trade Commission (FTC) enforces consumer protection laws. Publications available from the FTC include:

    • "Who Cares: Sources of Information About Health Care Products and Services"
    • "Fraudulent Health Claims: Don’t Be Fooled"

Consumer Response Center
Federal Trade Commission
Washington, DC 20580
Telephone: 1–877–FTC–HELP (1–877–382–4357) (toll free)
TTY (for deaf and hard of hearing callers): 202–326–2502
Web site:


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