Coenzyme Q10 Research

A Summary of our Research

Basic Cardiovascular Function

In a variety of laboratory and animal experiments, coenzyme Q10 has been shown to be effective in reducing the adverse effects of ischaemia-reperfusion injury.  It can enhance energy production in mitochondria and cells and improve clinical outcomes .1-3

Coenzyme Q10 in Hypertension

There have been twelve clinical trials of coenzyme Q10 in the treatment of hypertension.  Four were prospective randomised trials and eights were before and after studies.  Overall, the twelve studies showed a fall in blood pressure of 17 mmHg systolic and 10 mmHg diastolic.  coenzyme Q10 has shown to be particularly effective with hypertension in diabetics were it not only lowers blood pressure but also improves diabetic control.  The mechanism of action of coenzyme Q10 in hypertension is almost certainly as an antioxidant, were it scavenges free oxygen radicals, protects the endothelium from oxygen free radical attack and thus improves vascular dilatation by nitric oxide.2, 4-11

Coenzyme Q10 in Heart Failure

A review of all the published trials of coenzyme Q10 in heart failure was first published in 1997.  This showed a beneficial effect of coenzyme Q10.  We updated the findings for this analysis by analysing nine randomised trials of coenzyme Q10 in heart failure published up to 2003 (2).  Only prospective randomised, double-blind and placebo-controlled trials were included in that analysis.  The three parameters with adequate numbers of patients for meaningful analysis were coenzyme Q10 levels (5 trials), ejection fraction at rest (7 trials) and mortality (5 trials).  Other parameters were measured in only two trials each.  For CoQ10 levels (279 patients), the weighted mean differences was 1.4 µg/µl representing an increase of 161%.  For ejection fraction at rest (384 patients) the weighted mean difference showed a trend in favour of CoQ10 of 1.9% (95% confidence limits - 0.13% to 3.9%).

An updated meta-analysis has been published recently (12).  This meta-analysis included eleven randomised trials of coenzyme Q10 in heart failure including cross-over and parallel trial designs.  The main end-point of resting ejection fraction showed an absolute 3.7% net improvement (P < 0.0006).  Stroke index also increased by 5.8 ml (P = 0.02).  Sub-group analyses showed that the ejection fraction improvement was more pronounced when only idiopathic cardiomyopathy was evaluated and among patients not receiving angiotensin converting enzyme (ACE) inhibitors.  When the results were re-analysed using a less conservative statistical test (fixed effects modelling) than was used in the initial analysis (random effects modelling), increases in cardiac output, cardiac index and stroke volume all became significant.

In light of the encouraging findings of the abovementioned meta-analyses it is not unreasonable to recommend to patients with symptomatic heart failure despite conventional therapy or those who are experiencing side effects from conventional therapy (especially ACE inhibitors) to take 150-300 mg of coenzyme Q10 daily and to monitor CoQ10 blood levels and clinical response.13

Coenzyme Q10 in Cardiac Surgery

coenzyme Q10 has been used in the cardiothoracic surgical setting in order to offset reperfusion-related increases in free radical formation and oxidative stress.  From 1982 to 2004 at least eight controlled trials of coenzyme Q10 in cardiac surgery have been published.14-22 All but one of these have shown a beneficial effect of some kind.  The one trial showing an absence of effect20 used oral CoQ10 for only 12 hours before surgery, an inadequate time frame for sufficient dosing to increase myocardial levels.  A prospective randomised, placebo-controlled trial from our unit of 300 mg per day of oral CoQ10 for two weeks preoperatively in 121 coronary bypass or valve replacement procedures showed increased mitochondrial CoQ10 content, increased effiency of mitochondrial energy production and improved contractile function in myocardial trabeculae.22

Cardiac Arrhythmias

There is some anecdotal experimental and clinical evidence of a beneficial effect of coenzyme Q10 in cardiac arrhythmias.  This would make sense in light of the effect of coenzyme Q10 in improving cellular membrane function and energy production, thus reducing the myocardial ischaemia that can generate arrhythmias.

Side Effects and Drug Interactions

coenzyme Q10 is essentially devoid of side effects.  There are occasional reports of gastrointestinal upset but no other major side effects.

Does coenzyme Q10 Interfere with Warfarin?

The literature contains a case report describing a reduction in the efficacy of warfarin caused by coenzyme Q10.  However, a subsequent prospective randomised trial of coenzyme Q10 showed no effect of coenzyme Q10 on coagulation status in patients receiving Warfarin therapy.  In summary, anticoagulation should be closely monitored during the initiation or withdrawal of coenzyme Q10 therapy.23


Doses between 150 and 300 mg per day are used for heart failure or hypertension.  Ideally, dosage is adjusted according to serum coenzyme Q10 levels. Therapeutic effects are most likely when serum levels are increased to twice normal.


There is accumulating laboratory and clinical evidence of the efficacy of coenzyme Q10 in a variety of cardiovascular disorders.  Not all of these have been conclusively proven, but in the absence of side effects, it is reasonable to administer coenzyme Q10 to selected patients with various types of cardiovascular disease and gauge the response.


  1. Rosenfeldt FL, Pepe S, Linnane A, Nagley P, Rowland M, Ou R, Marasco S, Lyon W, Esmore D.  Coenzyme Q10 protects the ageing heart against stress: studies in rats, human tissues and patients.  Ann N Y Acad Sci 2002; 959:355-359.
  2. Rosenfeldt FL, Hilton D, Pepe S, Krum H.  Systematic review of coenzyme Q10 in physical exercise, hypertension and heart failure.  Biofactors 2003; 18:91-100.
  3. Rosenfeldt FL, Miller F, Nagley P, Hadj A, Marasco S, Quick D, Sheeran F, Wowk M, Pepe S.  Response of the Senescent Heart to Stress.  Ann N Y Acad Sci 2004; 1019:1-7.
  4. Burke BE, Neuenschwander R, Olson RD.  Randomised double-blind, placebo-controlled trial of coenzyme Q10 in isolated systolic hypertension.  South Med J 2001; 94:1112-1117.
  5. Digiesi V, Cantini F, Bisi G, Guarino GC, Oradei A, Littarru GP.  Mechanism of action of coenzyme Q10 in essential hypertension.  Curr Ther Res 1992; 5:668-672.
  6. Digiesi V, Cantini F, Oradei A, Bisi G, Guarino GC, Brocchi A, Bellandi F, Mancini M, Littarru GP.  Coenzyme Q10 in essential hypertension.  Mol Aspects Med 1994; 15 Suppl:s257-263.
  7. Folkers K, Drzewoski J, Richardson PC, Ellis J, Shizukuishi S, Baker L.  Bioenergetics in clinical medicine.  XVI: Reduction of Hypertension in patients by therapy with coenzyme Q10.  Res Communic Chem Path Pharmacol 1981; 31:129-139.
  8. Hodgson JM, Watts GF, Playford DA, Burke V, Croft KD.  Coenzyme Q10 improves blood pressure and glycaemic control: a controlled trial in subjects with type 2 diabetes.  Eur J Clin Nutr 2002; 56:1137-1142.
  9. Langsjoen P, Willis R, Folkers K. Treatment of essential hypertension with coenzyme Q10.  Mol Aspects Med 1994; 15 Suppl:S265-72.
  10. Singh RB, Niaz MA, Rastogi SS, Shukla PK, Thakur AS. Effect of hydrosoluble coenzyme Q10 on blood pressures and insulin resistance in hypertensive patients with coronary artery disease.  J Hum Hypertens 1999 Mar; 13(3):203-8.
  11. Yamagami T, Shibata N, Folkers K. Bioenergetics in clinical medicine. Studies on coenzyme Q10 and essential hypertension.  Res Commun Chem Pathol Pharmacol 1975 Jun; 11(2):273-88.
  12. Sander S, Coleman CI, Patel AA, Kluger J, White CM. The impact of coenzyme Q10 on systolic function in patients with chronic heart failure.  J Card Fail 2006 Aug; 12(6):464-72.
  13. Pepe S, Marasco SF, Haas SJ, Sheeran FL, Krum H, Rosenfeldt FL. Coenzyme Q10 in cardiovascular disease.  Mitochondrion 2007 Jun; 7 Suppl:S154-67.
  14. Tanaka J, Tominaga R, Yoshitoshi M, Matsui K, Komori M, Sese A, et al. Coenzyme Q10: the prophylactic effect on low cardiac output following cardiac valve replacement.  Ann Thorac Surg 1982 Feb; 33(2):145-51.

Who are We?

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

Franklin Rosenfeldt