Clinical Uses of Coenzyme Q10: Cardiovascular diseases

Effect of Coenzyme Q10 on the heart and Circulation

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

CoQ10 in Heart Failure

The Q-SYMBIO Trial (Morensten et al., 2014) is a landmark international, multicentre randomised study that examined the effects of CoQ10 (oxidised form) in 420 patients with moderate heart failure. Treatment with CoQ10 as an adjunct to maximum conventional therapy significantly reduced hospitalisations for HF, improved clinical state (NYHA Class) and reduced all cause mortality by 42% relative to placebo (10% with placebo to 18% with treatment). These effects were seen following a chronic administration period of two years with no short-term benefits observed following 16 weeks’ treatment. In recent reviews of the literature, compared to placebo coenzyme Q10 supplementation significantly improved left ventricular ejection fraction by a 3.7% average overall and by 6.7% in patients not receiving angiotensin-converting enzyme inhibitors (Sander et al., 2006; Fotino et al., 2013). Using a less conservative statistical analysis (fixed effect modeling) significant improvements were also seen in other measures indicating improved heart function (stroke volume, cardiac index). Overall, the included studies in these reviews articles tested coenzyme Q10 doses of between 60-300mg after durations between 4-24 weeks and 60-200mg dose between 1-24 weeks. In 2003 we published a review analysing 9 randomised trials of C0Q10 in heart failure (Rosenfeldt et al., 2003). 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 already receiving ACE inhibitor drugs. Nutrients in the food we eat need to be broken down (digested) into tiny molecules so that our body can absorb them through our gut where they travel to different parts of our body through the blood stream, where they are needed for essential bodily functions. Digestion begins in the mouth where we munch on food, breaking it down into smaller pieces with the help of important enzymes released in our saliva. When we swallow food, the stomach breaks food down into even smaller pieces, which then travel into the intestines. Nutrients get absorbed through the intestines (gut) and into the blood stream. CoQ10 is a fat-soluble nutrient, which means that only fat can break it down into a form that can be used in the body. Because CoQ10 is fat-soluble it is generally poorly absorbed in the gut (intestines). Some researchers and clinicians have suggested that patients with severe heart failure (NYHA class IV) are unable to reach optimal blood coenzyme Q10 levels, even when taking high daily doses (up to 900mg/day), because these patients have fluid and swelling in the gut (intestinal oedema), which can effect coenzyme Q10 absorption. Researchers and clinicians Langsgoen and Langsgoen (2008) set out to test this theory in an observational study on seven patients with chronic heart failure. These patients still had very low levels of coenzyme Q10 in the blood (1.6µg/ml) despite taking recommended daily doses (150-600mg/day; average 450 mg CoQ10 ubiquinone). These patients were asked by the clinician to also take a different type of CoQ10 (ubiquinol), which has better absorbability and bioavailability, of doses between 450-900 mg/day (average 580 mg/day). These higher doses of CoQ10 resulted in an increase in CoQ10 blood levels (6.5µg/ml), improvements in ejection fraction (from 22% to 39%) and improvements in heart failure symptoms (from a mean of NYHA class IV to NYHA class II). A Cochrane review published in 2014 concluded that “no conclusions can be drawn on the benefits or harms of coenzyme Q10 in heart failure at this time” (Madmani et al., 2014).However this review was completed before the publication of the Q-Symbio Study. In light of the encouraging findings from the above-mentioned studies, it is reasonable for patients with symptomatic heart failure to take 150-300 mg of CoQ10 daily. The reason that there are not more large studies of CoQ10 in heart failure and other conditions is that CoQ10 is not a patentable drug and hence there is litle incentive for large pharmaceutical companies to fund such trials.

CoQ10 and High Blood Pressure

Numerous trials have demonstrated the anti-hypertensive (blood pressure lowering) effects of CoQ10. Overall, 12 studies identified in a rigorous review of the scientific literature, showed a decrease of 17 mmHg in systolic and 10 mmHg in diastolic blood pressure following CoQ10 supplementation (Rosenfeldt et al., 2007). Researchers who conducted a more recent review of the literature (systematic review and meta-analysis) confirmed that blood pressure was reduced in hypertensive (high blood pressure) individuals compared to those taking a placebo pill. Although these authors conclude that there is not enough evidence support the long-term use of CoQ10 in lowering blood pressure, their opinion is based on the review of 3 trials conducted on CoQ10, and we cannot dismiss other trials supporting the benefits of CoQ10 supplementation on reducing blood pressure. One study showed that CoQ10 may be effective in diabetics where it improves glycemic control in patients with diabetes and at the same time may lower blood pressure (Hodgson et al, 2002). The mechanism of action of CoQ10 in lowering blood pressure is possibly due its antioxidant effects where it scavenges free radicals and improves the function of blood vessels by preserving nitric oxide. However, more studies are needed to confirm the blood pressure lowering effects in diabetes. Overall, in these studies side effects as a result of taking CoQ10 were either absent, minimal or no different to placebo. CoQ10 is considered to be safe when taken on its own or with prescribed anti-hypertensive pharmaceuticals (Rosenfeldt et al, 2007).

CoQ10 and Heart Surgery

CoQ10 has been used in heart surgery to reduce the effects of oxidative stress and improve the function and energy production of heart muscle (Rosenfeldt 2005). Coenzyme Q10 can reduce surgical complications; shorten recovery times and hospital stays. One trial showing absence of effect used oral CoQ10 for only 12 hours before surgery, an inadequate time frame to increase CoQ10 levels in the heart. In a prospective randomised trial of CoQ10 published from our own unit 300 mg of CoQ10 per day Q10 and other metabolic supplements was administered for 1-2 weeks on average prior to surgery and for 30 days post surgery (Leong JW et al. 2010). This was shown to reduce damage to the heart muscle, reduce recovery time by 1.2 days and reduce hospital costs.

Cardiac Arrhythmias

There is 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.  

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.


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 Cardiovascular Medicine Research Unit, headed by Professor Franklin Rosenfeldt.

Franklin Rosenfeldt