Cardiovascular Effects of Coenzyme Q10

Effect of Coenzyme Q10 on the heart and Circulation

In a variety of experiments in the laboratory, coenzyme Q10 (CoQ10) has been shown to be effective in preventing injury to the heart.  It can enhance energy production in the heart muscle and improve recovery of patients after heart surgery and other stresses.

CoQ10 and High Blood Pressure

At least 12 trials have been published using CoQ10 to treat high blood pressure and another trial is currently in progress is Christchurch, New Zealand and is expected to be completed in 2010.  Overall the 12 studies showed a decrease of 17 mmHg in systolic blood pressure and 12 mmHg in diastolic blood pressure.  CoQ10 has been particularly effective in diabetics where it improves control of diabetes and at the same time can lower blood pressure.  The mechanism of action of CoQ10 in lowering blood pressure is almost certainly as an antioxidant where it scavenges free radicals and improves the function of blood vessels by preserving nitric oxide.

CoQ10 in Heart Failure

A review of all published trials of CoQ10 in heart failure was first published in 1997.  This showed a beneficial effect of CoQ10.  In 2003 we updated the findings of this analysis by analysing 9 randomised trials of C0Q10 in heart failure.  Only the most rigorously conducted trials were included in this analysis.  These showed an increase in CoQ10 levels measured in the blood, and an increase in the contractility of the heart.  There was an increase in the pumping ability of the heart.

A more recent analysis of CoQ10 in heart failure included 11 randomised trials of CoQ10 in heart failure including cross over and parallel designs.  The main endpoint (heart contraction) showed a 4% improvement.  The improvement was greatest in those that were not receiving ACE inhibitor drugs already.

In light of the encouraging findings for the abovementioned analysis, it is not unreasonable in patients with symptomatic heart failure and those who are experiencing side effects from conventional treatment to take 150-300 mg of CoQ10 daily.

CoQ10 and Heart Surgery

CoQ10 has been used in heart surgery to reduce the effects of oxidative stress.  From 1982 to 2004 at least 8 controlled trials of CoQ10 in heart surgery have been published.  All but one of these have shown a beneficial effect of some kind.  The one trial showing absence of effect used oral CoQ10 for only 12 hours before surgery, an inadequate time frame in increase CoQ10 levels in the heart.  A prospective randomised trial of CoQ10 published from our own unit using 300 mg og CoQ10 per day showed increased CoQ10 levels in the heart, more efficient energy production in the heart muscle and improved heart pump function.

Cardiac Arrhythmias

There is good evidence of a beneficial effect of CoQ10 in rhythm disturbances of the heart.  This makes sense because CoQ10 can improve energy production in the heart cells and reduce disturbances in blood flow in the heart muscle that can create rhythm problems and palpitations felt by the patient.  

CoQ10 is essentially devoid of side effects and drug interactions.  There are occasional reports of gastrointestinal upset but no other major side effect.

Does CoQ10 Interfere with the Anticoagulant Drug Warfarin?

The literature contains a case report describing a reduction in the efficacy of warfarin caused by CoQ10, however a subsequent trial failed to show any effect of CoQ10 on blood clotting in patients receiving warfarin therapy.  In summary, anticoagulation should be closely monitored during the initiation or withdrawal of CoQ10 therapy.


Dosage of 150-300 mg per day are used for heart failure and hypertension (high blood pressure).  Ideally dosage is adjusted according to serum CoQ10 levels.  Beneficial effects are most likely when blood levels are increased to twice normal.

Cost of CoQ10

CoQ10 is expensive compared to some other dietary supplements.  In Japan and certain European countries, patients can receive a government support for CoQ10 therapy.  However, this is not the case in the United States or in Australia, where the patient must bear the full cost of therapy.  CoQ10 should be obtained from reputable suppliers so that its quality is predictable.  Measurement of CoQ10 levels in the blood can easily distinguish between effective and ineffective therapies.


There is accumulating evidence, both in the laboratory and in clinical practice, of the effectiveness of CoQ10 in a variety of disorders of the heart and circulation.  Not all of these benefits have been conclusively proven, but in the absence of side effects, it is reasonable for patients with various types of cardiovascular disease to use CoQ10 and monitor the results.

Who are we?

This website is published by the Cardiac Surgical Research team at the Alfred Hospital, headed by Professor Franklin Rosenfeldt.

Franklin Rosenfeldt