Have any clinical trials (research studies with people) of coenzyme Q10 been conducted?
There have been no well-designed clinical trials involving large numbers of patients to study the use of coenzyme Q10 in cancer treatment. There have been some clinical trials with small numbers of people, but the way the studies were done and the amount of information reported made it unclear if benefits were caused by the coenzyme Q10 or by something else. Most of the trials were not randomized or controlled. Randomized controlled trials give the highest level of evidence:
- In randomized trials, volunteers are assigned randomly (by chance) to one of 2 or more groups that compare different factors related to the treatment.
- In controlled trials, one group (called the control group) does not receive the new treatment being studied. The control group is then compared to the groups that receive the new treatment, to see if the new treatment makes a difference.
Some research studies are published in scientific journals. Most scientific journals have experts who review research reports before they are published, to make sure that the evidence and conclusions are sound. This is called peer review. Studies published in peer-reviewed scientific journals are considered better evidence. No randomized clinical trials of coenzyme Q10 as a treatment for cancer have been published in a peer-reviewed scientific journal.
The following has been reported from studies of coenzyme Q10 in people:
Randomized trial of coenzyme Q10 and doxorubicin
A randomized trial of 20 patients looked at whether coenzyme Q10 would protect the heart from the damage caused by the anthracycline drug doxorubicin. The results of this trial and others have shown that coenzyme Q10 decreases the harmful effects of doxorubicin on the heart.
Studies of coenzyme Q10 as an adjuvant therapy for breast cancer
Small studies have been done on the use of coenzyme Q10 after standard treatment in patients with breast cancer:
In a study of coenzyme Q10 in 32 breast cancer patients, it was reported that some signs and symptoms of cancer went away in 6 patients. Details were given for only 3 of the 6 patients. The researchers also reported that all the patients in the study used less pain medicine, had improved quality of life, and did not lose weight during treatment.
- In a follow-up study, two patients who had breast cancer remaining after surgery were treated with high doses of coenzyme Q10 for 3 to 4 months. It was reported that after treatment with high-dose coenzyme Q10, the cancer was completely gone in both patients.
- In a third study led by the same researchers, 3 breast cancer patients were given high-dose coenzyme Q10 and followed for 3 to 5 years. The study reported that 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 breast cancer found after surgery.
It is not clear, however, if the benefits reported in these studies were caused by coenzyme Q10 therapy or something else. The studies had the following weaknesses:
- The studies were not randomized or controlled.
- The patients used other supplements in addition to coenzyme Q10.
- The patients received standard treatments before or during the coenzyme Q10 therapy.
- Details were not reported for all patients in the studies.
Anecdotal reports of coenzyme Q10
Anecdotal reports are incomplete descriptions of the medical and treatment history of one or more patients. There have been anecdotal reports that coenzyme Q10 has helped some cancer patients live longer, including patients with cancers of the pancreas, lung, colon, rectum, and prostate. The patients described in these reports, however, also received treatments other than coenzyme Q10, including chemotherapy, radiation therapy, and surgery.
Have any side effects or risks been reported from coenzyme Q10?
No serious side effects have been reported from the use of coenzyme Q10. The most common side effects include the following:
- Insomnia (being unable to fall sleep or stay asleep).
- Higher than normal levels of liver enzymes.
- Pain in the upper part of the abdomen.
- Feeling sensitive to light.
- Feeling irritable.
- Feeling very tired.
It is important to check with health care providers to find out if coenzyme Q10 can be safely used along with other drugs. Certain drugs, such as those that are used to lower cholesterol, blood pressure, or blood sugar levels, may decrease the effects of coenzyme Q10. Coenzyme Q10 may change the way the body uses warfarin (a drug that prevents the blood from clotting) and insulin.
As noted in Question 1, the body uses coenzyme Q10 as an antioxidant. Antioxidants protect cells from free radicals. Some conventional cancer therapies, such as anticancer drugs and radiation treatments, kill cancer cells in part by causing free radicals to form. Researchers are studying whether using coenzyme Q10 along with conventional therapies has any effect, good or bad, on the way these conventional therapies work in the body.
Is coenzyme Q10 approved by the US Food and Drug Administration (FDA) for use as a cancer treatment in the United States?
Coenzyme Q10 is sold as a dietary supplement and is not approved by the FDA for use as a cancer treatment. In the United States, dietary supplements are regulated as foods, not drugs. This means that approval by the FDA is not required before coenzyme Q10 is sold, unless specific health claims are made about the supplement. Also, the way companies make coenzyme Q10 is not regulated. Different batches and brands of coenzyme Q10 supplements may be different from each other.