Evidence Trace, complete trial record
In plain terms
In plain terms: Coenzyme Q10 (CoQ10) has some human trial evidence supporting it, but the evidence is not yet strong enough for EBL to call it established. It is worth knowing about and worth discussing with your clinician.
Coenzyme Q10 (CoQ10)
B
Supported: a good trial, backed by more
The endpoint this grade is based on: Hard clinical endpoint (mortality, major event), Chronic heart failure as an adjunct to standard therapy; mitochondrial electron transport is the proposed mechanism
The evidence as the record states it
Mortensen et al. (Journal of the American College of Cardiology: Heart Failure, 2014; PMID 25282031): the Q-SYMBIO randomized controlled trial: coenzyme Q10 reduced major adverse cardiovascular events and mortality in chronic heart failure. Morisco et al. (Clinical Investigator, 1993; PMID 8241697): 641 patients with NYHA class III or IV heart failure, fewer hospitalizations for worsening heart failure over one year. Xu et al. (BMC Cardiovascular Disorders, 2024; PMID 39462324): 33 studies, lower all-cause mortality and heart-failure hospitalization and lower BNP, which its own authors rate moderate to low quality. Al Saadi et al. (Cochrane Database of Systematic Reviews, 2021; PMID 35608922): mortality from one study of 420 people, heart-failure hospitalization from two studies of 1,061, and no convincing evidence to support or refute. Claxton et al. (Health Technology Assessment, 2022; PMID 35076012): pooled mortality inconclusive (RR 0.68, 95% CI 0.45 to 1.03), with a new independent trial called for. Grade B for heart-failure adjunct use: one strong trial, not yet independently replicated on mortality.
PMID 25282031 PMID 39462324 PMID 35608922 PMID 8241697 PMID 35076012
Evidence by specific use
Chronic heart failure events, including hospitalization, as an adjunct to standard therapy
Grade B
Q-SYMBIO (Journal of the American College of Cardiology: Heart Failure, 2014; PMID 25282031) reported fewer major adverse cardiovascular events and fewer deaths in 420 patients. No independent group has reproduced the mortality result. Morisco et al. (1993; PMID 8241697) reported fewer heart-failure hospitalizations in 641 patients, and Cochrane (PMID 35608922) pools the two for that outcome. A 2024 pooled analysis (PMID 39462324) reports lower mortality and hospitalization across 33 mostly small studies of moderate to low quality. Grade B: a hard-outcome trial supported by an independent trial on one component of its composite, short of the independent replication of the mortality result an A requires. The not-replicated flag was removed in October 2026: it was true of mortality and false of hospitalization, and the written B asks only that the trial not stand alone.
PMID 25282031 PMID 8241697 PMID 39462324 PMID 35608922 PMID 35076012
Statin-associated muscle symptoms
Grade C
The evidence is divided and every endpoint is subjective. Qu 2018 (PMID 30371340, 12 RCTs, 575 patients) reported reduced muscle pain, weakness, cramp and tiredness with no change in creatine kinase. Kennedy 2020 (PMID 32179207) found no benefit for myalgia or adherence. Kovacic 2025 (PMID 41158831, 7 RCTs, 389 patients) reported reduced pain intensity, significant in 4 of 7 trials. Self-report endpoints cap at Grade B; the disagreement between meta-analyses holds this at C.
PMID 30371340 PMID 32179207 PMID 41158831
Why Grade B and not Grade A
Grade B reflects moderate human evidence -- typically a single strong trial, multiple smaller trials, or surrogate endpoint data without hard clinical outcome replication. To reach Grade A, Coenzyme Q10 (CoQ10) would require at least one additional independent randomized trial demonstrating a hard clinical endpoint or objectively measured functional outcome in a comparable population.
What this grade covers and what it does not
Grade B: one randomized trial on a hard outcome, supported by further trials rather than standing alone, but not reproduced by an independent group on the outcome it reports. Q-SYMBIO (Mortensen et al., Journal of the American College of Cardiology: Heart Failure, 2014; PMID 25282031) randomized 420 people with chronic heart failure and reported fewer major cardiovascular events and fewer deaths. WHY NOT A: Grade A needs the effect a record reports to replicate across independent research groups. The mortality result rests on Q-SYMBIO alone: the Cochrane review (Al Saadi et al., 2021; PMID 35608922) could pool only that one study of 420 people for mortality and concludes there is no convincing evidence to support or refute CoQ10 for heart failure, and the UK NIHR review (Claxton et al., 2022; PMID 35076012) found the pooled mortality result inconclusive and called for a new independent trial. WHY NOT C: the result does not stand alone. An independent trial from Naples (Morisco et al., 1993; PMID 8241697) randomized 641 patients and reported fewer hospitalizations for worsening heart failure, one part of the Q-SYMBIO composite, and Cochrane pools the two for that outcome. That second trial is a three-page 1993 report, measured a different endpoint, and ran on the heart-failure care of its time, which is why it supports a B and cannot carry an A. WHAT THIS GRADE DOES NOT COVER: the B is for use ALONGSIDE standard heart-failure therapy in people who have heart failure. It is not a grade for CoQ10 as a general energy or longevity supplement in healthy adults, where no trial has tested a clinical outcome. It does not cover statin-associated muscle symptoms, the other reason CoQ10 is commonly taken, which sits at C on this same record. And it is a grade on the form that was studied: the trial evidence is on ubiquinone, not on ubiquinol, which is a different preparation that this evidence does not reach.
What would move this grade
An independent randomized trial demonstrating a hard clinical endpoint -- mortality, major adverse event, or objectively confirmed functional improvement -- in an adequately powered sample, with results independently replicated, would support Grade A.
How to track whether this is working
Heart-failure symptom burden and functional capacity, which is the graded heart-failure use. Blood CoQ10 (optional) and lipid panel. Statin-associated muscle symptoms are graded separately on this record at C and are not what the heart-failure grade covers.