Coenzyme Q10 (PDQR)

What is coenzyme Q 10 ?

Coenzyme Q   10 (also known as CoQ 10 , Q 10 , vitamin Q 10 , 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 Q 10 refer to parts of the compound's chemical structure.

Coenzyme Q 10 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 Q 10 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 Q 10 decrease as people get older.

What is the history of the discovery and use of coenzyme Q 10 as a complementary or alternative treatment for cancer?

Coenzyme Q 10 was first identified in 1957. Its chemical structure was determined in 1958. Interest in coenzyme Q 10 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 Q 10 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 Q 10 works in the body to produce energy and act as an antioxidant. Some studies have suggested that coenzyme Q 10 stimulates the immune system and increases resistance to disease. In part because of this, researchers have theorized that coenzyme Q 10 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.)

How is coenzyme Q 10 administered?

Coenzyme Q 10 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 Q 10 is given by injection.

Have any preclinical (laboratory or animal) studies been conducted using coenzyme Q 10 ?

Laboratory studies of coenzyme Q 10 have focused on describing its chemical structure and how it works in the body. Animal studies have found that coenzyme Q 10 stimulated the immune system and increased resistance to certain infections and types of cancer. Coenzyme Q 10 helped to protect the hearts of animals given the anticancer drug doxorubicin, which can cause damage to the heart muscle.

Have any clinical trials (research studies with people) of coenzyme Q 10 been conducted?

The promising results from animal studies of coenzyme Q 10 and the anticancer drug doxorubicin led researchers to test coenzyme Q 10 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 Q 10 would protect the heart from the damage caused by doxorubicin. The results of this trial and others have confirmed that coenzyme Q 10 decreases the effects of doxorubicin on the heart. No report of a randomized clinical trial of coenzyme Q 10 as a treatment for cancer, however, has been published in a peer-reviewed scientific journal.

Three other small studies were conducted using coenzyme Q 10 as a dietary supplement in patients undergoing conventional cancer treatment. In the following studies, the researchers explored the potential use of coenzyme Q 10 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 Q 10 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). The data were not complete, however, and information that suggested remission was presented for only 3 of the 6 patients. All of the participants reported decreased use of painkillers, improved quality of life, and absence of weight loss during treatment.

•  In a follow-up study, one new patient and one of the patients who had a reported remission were treated with high doses of coenzyme Q 10 for 3 to 4 months. Both of the patients had breast cancer remaining after surgery. After the period of high-dose coenzyme Q 10 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 6 patients with a reported remission in the first study took part in the follow-up study.

•  In a third study conducted by the same researchers, 3 breast cancer patients were given high-dose coenzyme Q 10 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 Q 10 ), and there may have been differences in the characteristics of patients who were selected for the follow-up 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 Q 10 , and they received standard treatment either during or just before coenzyme Q 10 supplementation. Therefore, it is impossible to determine whether any of the beneficial results were directly related to coenzyme Q 10 therapy.

There have also been anecdotal reports that coenzyme Q 10 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 Q 10 , including chemotherapy, radiation therapy, and surgery.

Have any side effects or risks been reported from coenzyme Q 10 ?

No serious side effects have been reported from the use of coenzyme Q 10 . Some patients using coenzyme Q 10 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 Q 10 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 Q 10 . Coenzyme Q 10 may also alter the body's response to warfarin (a drug that prevents the blood from clotting) and insulin.

As noted in Question 1 , coenzyme Q 10 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 Q 10 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).

Is coenzyme Q 10 approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

Several companies distribute coenzyme Q 10 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 variations in the composition of the supplements from one batch to another.

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 Q 10 as a treatment for cancer.

Study Suggests Coenzyme Q10 Slows Functional Decline in Parkinson's Disease

For release: Monday, October 14, 2002

Overview    Results of the first placebo-controlled, multicenter clinical trial of the compound coenzyme Q10 suggest that it can slow disease progression in patients with early-stage Parkinson's disease (PD). While the results must be confirmed in a larger study, they provide hope that this compound may ultimately provide a new way of treating PD.

Results of the first placebo-controlled, multicenter clinical trial of the compound coenzyme Q 10 suggest that it can slow disease progression in patients with early-stage Parkinson's disease (PD). While the results must be confirmed in a larger study, they provide hope that this compound may ultimately provide a new way of treating PD.

The phase II study, led by Clifford Shults, M.D., of the University of California, San Diego (UCSD) School of Medicine, looked at a total of 80 PD patients at 10 centers across the country to determine if coenzyme Q 10 is safe and if it can slow the rate of functional decline. The study was funded by the National Institute of Neurological Disorders and Stroke (NINDS) and appears in the October 15, 2002, issue of the Archives of Neurology . 1

"This trial suggested that coenzyme Q 10 can slow the rate of deterioration in Parkinson's disease," says Dr. Shults. "However, before the compound is used widely, the results need to be confirmed in a larger group of patients."

PD is a chronic, progressive neurological disease that affects about 500,000 people in the United States. It results from the loss of brain cells that produce the neurotransmitter dopamine and causes tremor, stiffness of the limbs and trunk, impaired balance and coordination, and slowing of movements. Patients also sometimes develop other symptoms, including difficulty swallowing, disturbed sleep, and emotional problems. PD usually affects people over the age of 50, but it can affect younger people as well. While levodopa and other drugs can ease the symptoms of PD, none of the current treatments has been shown to slow the course of the disease.

The investigators believe coenzyme Q 10 works by improving the function of mitochondria, the "powerhouses" that produce energy in cells. Coenzyme Q 10 is an important link in the chain of chemical reactions that produces this energy. It also is a potent antioxidant - a chemical that "mops up" potentially harmful chemicals generated during normal metabolism. Previous studies carried out by Dr. Shults, Richard Haas, M.D., of UCSD and Flint Beal, M.D., of Cornell University have shown that coenzyme Q 10 levels in mitochondria from PD patients are reduced and that mitochondrial function in these patients is impaired. Animal studies have shown that coenzyme Q 10 can protect the area of the brain that is damaged in PD. Dr. Shults and colleagues also conducted a pilot study with PD patients which showed that consumption of up to 800 mg/day of coenzyme Q 10 was well-tolerated and significantly increased the level of coenzyme Q 10 in the blood.

All of the patients who took part in the new study had the three primary features of PD - tremor, stiffness, and slowed movements - and had been diagnosed with the disease within 5 years of the time they were enrolled. After an initial screening and baseline blood tests, the patients were randomly divided into four groups. Three of the groups received coenzyme Q 10 at three different doses (300 mg/day, 600 mg/day, and 1,200 mg/day), along with vitamin E, while a fourth group received a matching placebo that contained vitamin E alone. Each participant received a clinical evaluation 1 month later and every 4 months for a total of 16 months or until the investigator determined that the patient needed treatment with levodopa. None of the participants or the study investigators knew which treatment each patient had received until the study ended.

The investigators found that most side effects of coenzyme Q 10 were mild, and none of the patients required a reduction of their dose. The percentage of people receiving coenzyme Q 10 who reported side effects was not significantly different from that of the placebo group. During the study period, the group that received the largest dose of coenzyme Q 10 (1,200 mg/day) had 44 percent less decline in mental function, motor (movement) function, and ability to carry out activities of daily living, such as feeding or dressing themselves. The greatest effect was on activities of daily living. The groups that received 300 mg/day and 600 mg/day developed slightly less disability than the placebo group, but the effects were less than those in the group that received the highest dosage of coenzyme Q 10 .

The groups that received coenzyme Q 10 also had significant increases in the level of coenzyme Q 10 in their blood and a significant increase in energy-producing reactions within their mitochondria.

The results of this study suggest that doses of coenzyme Q 10 as high as 1,200 mg/day are safe and may be more effective than lower doses, says Dr. Shults. The findings are consistent with those of a recently published study of patients with early Huntington's disease - another degenerative neurological disorder - that showed slightly less functional decline in groups that received 600 mg/day of coenzyme Q 10 .

The new study also used an efficient phase II clinical trial design - developed by biostatistician David Oakes, Ph.D., of the University of Rochester, and other study investigators - which should be useful for testing other drugs that might slow the progression of PD, says Dr. Shults. The design allowed the researchers to study the effects of three doses plus a placebo in less than 3 years, and to obtain useful data about the compound's effectiveness.

Dr. Shults and his colleagues strongly caution patients against taking coenzyme Q 10 until a larger, definitive trial can be conducted. Because coenzyme Q 10 is classified as a dietary supplement, it is not regulated by the U.S. Food and Drug Administration. The versions of the supplement sold in stores may differ, they may not contain potentially beneficial amounts of the compound, and taking coenzyme Q 10 over a number of years may be costly, says Dr. Shults. In addition, the current study included only a small number of patients, and the findings may not extend to people in later stages of PD or to those who are at risk but have not been diagnosed with the disorder, he notes. Finally, if many people begin taking coenzyme Q 10 because of these early results, it might make it impossible for investigators to find enough patients to carry out definitive studies of the compound's effectiveness and the proper dosages, since patients must not be taking any treatments in order to be considered for enrollment in a definitive trial.

The investigators are now planning a larger clinical trial that will examine the effects of 1,200 mg/day of coenzyme Q 10 , and possibly a higher dose as well, in a larger number of patients.

The NINDS is a component of the National Institutes of Health in Bethesda, Maryland, and is the nation's primary supporter of biomedical research on the brain and nervous system.

1 Shults CW, Oakes D, Kieburtz K, Beal F, Haas R, Plumb S, Juncos JL, Nutt J, Shoulson I, Carter J, Kompoliti K, Perlmutter JS, Reich S, Stern M, Watts RL, Kurlan R, Molho E, Harrison M, Lew M, and the Parkinson Study Group. "Effects of coenzyme Q 10 in early Parkinson disease: evidence of slowing of the functional decline." Archives of Neurology , October 2002, Vol. 59, No. 10, pp. 1541-1550.

Reporters: for more information, contact Natalie Frazin or Margo Warren, 301-496-5751.

Date Last Modified: Friday, December 16, 2005