Does coenzyme Q10 protect the heart?

co enxyme q10

Coenzyme Q10 is normally produced by the human body, although deficiency may occur in patients with impaired CoQ10 biosynthesis due to severe metabolic or mitochondrial disorders, not enough dietary CoQ10 intake, or too much CoQ10 use by the body. Depending on the cause of CoQ10 deficiency, supplementation or increased dietary intake of CoQ10 and the vitamins and minerals needed to produce CoQ10 may be effective.

Coenzyme Q10 was first identified in 1957. Its chemical structure was determined in 1958. Interest in coenzyme Q10 as a possible treatment for cancer began in 1961, when it was found that some cancer patients had a lower than normal amount of it in their blood. 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 suggest that coenzyme Q10 may help the immune system work better. Partly because of this, coenzyme Q10 is used as adjuvant therapy for cancer. Adjuvant therapy is treatment given following the primary treatment to increase the chances of a cure.


CoQ10 is an antioxidant, a compound that blocks the actions of free radicals, activated oxygen molecules that can damage cells. Scientists also believe that CoQ10 may have an effect on the immune system.

CoQ10 is sometimes promoted as a treatment for cancer (most commonly breast cancer), often in combination with other vitamins. Supporters also claim CoQ10 supplements may protect the heart from the damaging effects of certain chemotherapy drugs, such as doxorubicin (Adriamycin).

Various web sites show that CoQ10 supplements are also promoted for heart disease, stroke, high blood pressure, muscular dystrophy, gum disease, chronic fatigue, Alzheimer’s Disease, AIDS, and other immune deficiencies. It’s touted to improve athletic performance and help people lose weight. Some claim that CoQ10 can reduce pain and weight loss in people with cancer. It’s also promoted to reduce the signs of aging when used in skin products.

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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.

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.

A Chinese research team published in the journal Atherosclerosis examined the effect of CoQ10 on the delicate endothelial lining of the coronary arteries. Endothelial dysfunction is known to be a progenitor to heart disease and heart attack. The scientists demonstrated that individuals placed on CoQ10 (300 mg per day for 12 weeks) showed marked improvement in arterial stiffness due to increased blood flow and improved cellular energy within their endothelial cells.

coenymeQ10 heart

Scientific evidence is mounting to support coenzyme Q10 as a powerful tool when used to improve cellular energy levels and fight the advances of cardiovascular disease. Most new research is now evolving around the reduced form of the coenzyme known as ubiquinol. Ubiquinol has been found to be up to eight times more potent than standard CoQ10 and lasts much longer in blood circulation. It is quite apparent that most health-minded individuals should supplement with CoQ10 (50 to 300 mg per day depending on cardiovascular health) to improve energy levels and improve vascular circulation to the heart.

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.

Because CoQ10 is a strong antioxidant, there are theoretical reasons to suspect that it might interfere with the effectiveness of chemotherapy and radiation therapy. At least one study showed that when mice with implanted human lung cancer were treated with radiation and given CoQ10, they had less slowdown in tumor growth than mice that were treated with radiation alone. This question has not been adequately studied in human clinical trials. CoQ did not affect the ability of doxorubicin (a chemotherapy drug) to kill breast cancer cells in laboratory dishes, but the effect of CoQ on chemotherapy in patients remains uncertain. Many oncologists would recommend avoiding CoQ10 and other antioxidant supplements during chemotherapy and radiation therapy, as well as for a few weeks before and after these treatments.

Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.

In the new study conducted by European researchers, heart failure patients taking 100 milligrams of CoQ10 three times daily, in addition to their other medications, had fewer heart events, fewer hospitalizations, and a lower risk of dying from any cause. However, there’s not a large enough body of evidence at this time to recommend the supplement to people with heart failure, said Clyde Yancy, MD, chief of cardiology at Northwestern Memorial Hospital and a spokesperson for the American Heart Association. “The data that we see now comes from a relatively small database with a low number of events. In a larger study, you may see something very different,” he said.

High Blood Pressure. Several small trials have found that coenzyme Q10 can cause an additional drop in blood pressure in people already taking antihypertensive medications. A total of 120 to 200 milligrams, divided into two separate doses, is typically used in studies of people with high blood pressure, according to a 2010 review published in the Cleveland Clinic Journal of Medicine. But as with heart failure patients, the benefits for people with hypertension are far from definitive. “We just don’t have the evidence that warrants a strong embrace of CoQ10 to prevent disease or treat established disease,” Dr. Yancy said.