Protocol
CoQ10 (ubiquinone) 300 mg/day
Q-SYMBIO reported fewer major adverse cardiovascular events in chronic heart failure with ubiquinone 100 mg three times a day, one trial nobody has independently repeated at the outcome level.
Grade C: human trials exist, but they are small, mixed or not yet repeated. This is not a finding that it does not work. How to read a grade →
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How this letter has changedLatest: October 2026 · Downgraded.
The protocol held B on one trial, Q-SYMBIO (Mortensen et al., JACC Heart Fail, 2014; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 25282031; 420 patients, ubiquinone 100 mg three times daily), with the not-replicated flag set, and was named for ubiquinol, a form no cited trial gave. The pooled analysis (Xu et al., BMC Cardiovasc Disord, 2024; PMID 39462324) rests on the same trial for mortality. Under the single-trial rule that is C, and the name now states the form and dose studied, CoQ10 (ubiquinone) 300 mg/day. The CoQ10 supplement record's heart-failure use is held at B pending a replication The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away. search. Decided October 2026 by editor adjudication (Arnold Sandlow, D.C.).PMID 25282031 PMID 39462324
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This protocol is CoQ10 at 300 mg a day, the dose and form used in one heart failure study. In that study of 420 people with heart failure, those taking CoQ10 for two years had fewer serious heart problems than those on a dummy pill. No outside group has repeated it. The study used ubiquinone, not ubiquinol, the form most often sold. People without heart failure were not tested.
Q-SYMBIO reported fewer major adverse cardiovascular events in chronic heart failure with ubiquinone 100 mg three times a day, one trial nobody has independently repeated at the outcome level. The protocol is named for the form and dose that trial gave. Ubiquinol, the form commonly sold, has no outcome trial on this record. Single pivotal trial: C.
Why this gradeGrade C, small or unreplicated trials. The reasoning, and what the grade does not cover.
Grade C on cardiovascular events in chronic heart failure, resting on one trial: Q-SYMBIO, a randomized double-blind Neither the participants nor the people assessing them know who received the real treatment until the trial ends. trial of 420 patients in which ubiquinone 100 mg three times daily reduced major adverse cardiovascular events against placebo An inactive substitute made to look like the real treatment, so participants cannot tell which one they received. over two years (Mortensen et al., 2014; PMID 25282031). The 2024 meta-analysis A study that pools the numbers from several trials into one combined estimate. (Xu et al.; PMID 39462324) pools it with smaller and lower-quality trials, and its mortality result rests on Q-SYMBIO. Under the written rule one pivotal trial nobody has independently repeated at the outcome level is C; moved from B in October 2026 by editor adjudication, pending the replication search on the supplement record's heart-failure use. FORM: the protocol is named for what Q-SYMBIO gave, ubiquinone at 300 mg a day. No cited outcome trial tested ubiquinol, the form commonly sold.
WHAT THIS GRADE DOES NOT COVERpeople without heart failure, statin muscle symptoms, energy or longevity claims, and ubiquinol as a substitute for ubiquinone.
A grade describes the human evidence for a named use. It is not advice, and it is not a judgment on any individual prescription. How the letters are decided →
The evidence, in fullTwo papers, each linked to its PubMed record.
Mortensen et al. (JACC Heart Fail, 2014; PMID 25282031), Q-SYMBIO: 420 patients with chronic heart failure randomized to ubiquinone 100 mg three times daily or placebo for two years; major adverse cardiovascular events 15 against 26 percent, with lower cardiovascular and all-cause mortality. Xu et al. (BMC Cardiovasc Disord, 2024; PMID 39462324): meta-analysis pooling Q-SYMBIO with smaller and lower-quality trials; the mortality result rests on Q-SYMBIO. One pivotal trial without independent replication at the outcome level is C under the written rule. FORM: both cited papers concern ubiquinone; no outcome evidence on this record attaches to ubiquinol. Moved from B in October 2026 by editor adjudication.
Plasma CoQ10 at baseline and 8 weeks: the cited trials administered ubiquinone at 100 mg three times daily and reported roughly a doubling of baseline plasma levels. For statin users, track subjective muscle pain and fatigue scores alongside CoQ10 levels, as the depletion A fall in a nutrient's level caused by a medication, for example through reduced absorption or increased loss. mechanism is the primary clinical rationale. Blood pressure and diastolic function are secondary endpoints An outcome a trial also measures but did not choose as its main test. with the most consistent RCT Randomized controlled trial: people are assigned to the treatment or a comparison by chance, so the groups differ only in what they received. It is the design that can show cause and effect. support.
Evidence notes: not independently replicated, randomized trial, meta-analysis
Endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score. graded: Major adverse cardiovascular events in chronic heart failure (hard)
Last reviewed: July 2026
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How EBL searched for the trials (1 search)
The search that was run, what it returned, and what was left out and why, so the absence of evidence can be checked as well as its presence.
("coenzyme Q10"[tiab] OR ubiquinone[tiab] OR ubiquinol[tiab]) AND "heart failure"[tiab] AND (mortality[tiab] OR cardiovascular events[tiab] OR hospitalization[tiab]) AND (randomized controlled trial[pt] OR meta-analysis[pt])Grades move when new trials publish. A free monthly email lists every grade EBL moved, with the reason and the trial behind it: the sign-up is on the Evidence Log →