Coenzyme Q10

updated

Coenzyme Q10 (CoQ10) is sold as a supplement, and an openFDA query on 9 October 2026 located no FDA-approved CoQ10 drug. Blood levels rise reliably with oral dosing, and one 420-patient trial reported fewer major cardiovascular events in heart failure, but results for statin muscle symptoms, exercise, Parkinson disease and Huntington disease are mixed or negative.

Coenzyme with oxidized (ubiquinone) and reduced (ubiquinol) forms

  • An openFDA query on 9 October 2026 for ubidecarenone, coenzyme Q10 and ubiquinol returned no application, so no FDA-approved CoQ10 drug was located.
  • Q-SYMBIO (420 patients with heart failure, 2 years): major adverse cardiovascular events 15% versus 26% (HR 0.50), but the 16-week symptom endpoints did not change; the Cochrane review's mortality estimate rests on this one trial.
  • Two statin muscle-symptom meta-analyses disagree: 12 trials (575 patients) found less muscle pain, and 7 trials (321 adults) found no benefit.
  • QE3 (600 people with early Parkinson disease) and 2CARE (609 with early Huntington disease) both stopped for futility.
  • In 40 older adults, 12 weeks of CoQ10 raised plasma CoQ10 but not muscle or muscle mitochondrial CoQ10; in 121 cardiac surgery patients, 2 weeks raised levels in heart tissue and heart mitochondria.
  • A meta-analysis of 24 trials in healthy adults found small, inconsistent exercise effects with very low to low certainty.

What is coenzyme Q10, and is it an approved drug?

Coenzyme Q10 (ubidecarenone) is the oxidized form, and ubiquinol is the reduced form. An openFDA query on 9 October 2026 found no FDA application, so no FDA-approved CoQ10 drug was located.

Coenzyme Q10 (ubidecarenone, the oxidized ubiquinone form) is C59H90O4 (863.3 g/mol, CAS 303-98-0). Ubiquinol, the reduced form, is C59H92O4 (865.4 g/mol, CAS 992-78-9). Products sell either form in different formulations, and many trial abstracts do not state the form, so blood levels and results should not be pooled across forms without checking.

An openFDA Drugs@FDA query on 9 October 2026 for ubidecarenone, coenzyme Q10 or ubiquinol (brand, generic and active-ingredient fields) returned no application, so no FDA-approved CoQ10 drug was located. The Cochrane heart failure review describes CoQ10 as a non-prescription nutritional supplement. Approvals outside the United States were not examined.

PubChem: coenzyme Q10 and ubiquinol identity

Chemical identity record

National Library of Medicine. PubChem compound records CID 5281915 (coenzyme Q10, ubidecarenone) and CID 9962735 (ubiquinol).

Coenzyme Q10 (ubidecarenone, the oxidized ubiquinone form): C59H90O4, 863.3 g/mol, CAS 303-98-0. Ubiquinol, the reduced form: CID 9962735, C59H92O4, 865.4 g/mol, CAS 992-78-9. Products sell either form in different formulations. Many trial abstracts do not state the form, and blood levels and results should not be pooled across forms without checking.

Participants / model
Chemical identity, not a clinical population
Treatment
Two defined redox forms
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

Identity record only; it says nothing about efficacy or safety. Ubiquinol-versus-ubiquinone absorption claims are not tested here.

Read the original source
openFDA query, 9 October 2026: no CoQ10 application

Regulatory record

U.S. Food and Drug Administration. openFDA Drugs@FDA query for ubidecarenone, coenzyme Q10 or ubiquinol (brand, generic and active-ingredient fields), run on 9 October 2026.

The query returned no application, so no FDA-approved CoQ10 drug was located. The Cochrane heart failure review describes CoQ10 as a non-prescription nutritional supplement.

Participants / model
FDA application database, not a clinical population
Treatment
Exact substance-name query
Follow-up
Query run on 9 October 2026
Study design
Dated US approval-record query
Funding
not stated in the source

A negative query on one date is not proof about every product or jurisdiction. Approvals outside the United States were not examined.

Read the original source
Cochrane review: 11 trials, 1573 participants, no convincing evidence either way

Systematic review and meta-analysis

Al Saadi T et al. Cochrane Database Syst Rev. 2021;(2)(2):CD008684. PMID 35608922.

The review found moderate-quality evidence that CoQ10 probably reduces all-cause mortality (RR 0.58, 95% CI 0.35 to 0.95), an estimate drawn from 1 study of 420 participants, and heart failure hospitalization (RR 0.62, 95% CI 0.49 to 0.78; 2 studies, 1061 participants). Effects on ejection fraction (very low quality) and exercise capacity were uncertain, and adverse events were inconclusive (RR 0.70, 95% CI 0.45 to 1.10). The authors state there is no convincing evidence to support or refute CoQ10 for heart failure.

Participants / model
People with heart failure across 11 randomized trials (1573 participants, all with unclear or high risk of bias in at least one domain)
Treatment
CoQ10 at varying doses versus placebo or conventional therapy
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 11 randomized trials
Funding
not stated in the source

The mortality estimate comes from a single trial of 420 participants.

Read the original source

What did the heart failure studies find?

One 420-patient trial reported fewer major cardiovascular events and deaths over 2 years, and a Cochrane review calls the evidence moderate quality for mortality but says there is no convincing evidence either way. A smaller trial in advanced heart failure raised serum levels without changing heart function.

Q-SYMBIO randomized 420 patients with moderate to severe chronic heart failure to CoQ10 100 mg three times daily or placebo, on top of standard therapy, for 2 years. The 16-week endpoints (NYHA class, 6-minute walk, NT-proBNP) did not change. The 2-year composite of major adverse cardiovascular events occurred in 15% versus 26% (HR 0.50, 95% CI 0.32 to 0.80), with lower cardiovascular mortality (9% versus 16%) and all-cause mortality (10% versus 18%). This is one trial.

A Cochrane review of 11 trials (1573 participants, all with unclear or high risk of bias in at least one domain) found moderate-quality evidence that CoQ10 probably reduces all-cause mortality (RR 0.58, 95% CI 0.35 to 0.95), an estimate drawn from 1 study of 420 participants, and heart failure hospitalization (RR 0.62, 95% CI 0.49 to 0.78; 2 studies, 1061 participants). Effects on ejection fraction (very low quality) and exercise capacity were uncertain, and adverse events were inconclusive. The authors state there is no convincing evidence to support or refute CoQ10 for heart failure.

In 55 patients with NYHA class III to IV heart failure and ejection fraction under 40% (46 completed), CoQ10 200 mg/day raised mean serum CoQ10 from 0.95 to 2.2 mcg/mL, but ejection fraction, peak oxygen consumption and exercise duration did not change versus placebo.

Q-SYMBIO: 420 patients with heart failure, 2 years, fewer major cardiovascular events

Randomized controlled trial

Mortensen SA et al. JACC Heart Fail. 2014;2(6):641-9. PMID 25282031.

The 16-week endpoints (NYHA class, 6-minute walk, NT-proBNP) did not change. The 2-year composite of major adverse cardiovascular events occurred in 15% versus 26% (HR 0.50, 95% CI 0.32 to 0.80), with lower cardiovascular mortality (9% versus 16%) and all-cause mortality (10% versus 18%).

Participants / model
420 patients with moderate to severe chronic heart failure
Treatment
Oral CoQ10 100 mg three times daily or placebo, on top of standard therapy
Follow-up
2 years
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

This is one trial. It drives the Cochrane review's moderate-quality mortality estimate.

Read the original source
Cochrane review: 11 trials, 1573 participants, no convincing evidence either way

Systematic review and meta-analysis

Al Saadi T et al. Cochrane Database Syst Rev. 2021;(2)(2):CD008684. PMID 35608922.

The review found moderate-quality evidence that CoQ10 probably reduces all-cause mortality (RR 0.58, 95% CI 0.35 to 0.95), an estimate drawn from 1 study of 420 participants, and heart failure hospitalization (RR 0.62, 95% CI 0.49 to 0.78; 2 studies, 1061 participants). Effects on ejection fraction (very low quality) and exercise capacity were uncertain, and adverse events were inconclusive (RR 0.70, 95% CI 0.45 to 1.10). The authors state there is no convincing evidence to support or refute CoQ10 for heart failure.

Participants / model
People with heart failure across 11 randomized trials (1573 participants, all with unclear or high risk of bias in at least one domain)
Treatment
CoQ10 at varying doses versus placebo or conventional therapy
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 11 randomized trials
Funding
not stated in the source

The mortality estimate comes from a single trial of 420 participants.

Read the original source
Advanced heart failure: 55 patients, serum CoQ10 doubled, no change in function

Randomized controlled trial

Khatta M et al. Ann Intern Med. 2000;132(8):636-40. PMID 10766682.

CoQ10 raised mean serum CoQ10 from 0.95 to 2.2 mcg/mL, but ejection fraction, peak oxygen consumption and exercise duration did not change versus placebo.

Participants / model
55 patients with NYHA class III to IV heart failure and ejection fraction under 40% on standard therapy (46 completed)
Treatment
Oral CoQ10 200 mg/day or placebo
Follow-up
not stated in the source
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

Applies to patients with advanced heart failure.

Read the original source

Does CoQ10 help with statin muscle symptoms?

The evidence splits. One meta-analysis of 12 trials found less muscle pain, another of 7 trials found no benefit, and the best-controlled trial in confirmed statin myalgia found no improvement.

A meta-analysis of 12 randomized trials (575 statin-treated patients) found CoQ10 reduced statin-associated muscle pain (WMD -1.60, 95% CI -1.75 to -1.44), weakness, cramps and tiredness versus placebo, without lowering creatine kinase (WMD 0.09, 95% CI -0.06 to 0.24).

A meta-analysis of 7 randomized trials (321 adults with statin-associated myalgia) found no benefit on myalgia (WMD -0.42, 95% CI -1.47 to 0.62) and no effect on staying on statin therapy (RR 0.99, 95% CI 0.81 to 1.20). Only 2 of the included trials were positive.

In a trial that first confirmed statin myalgia, 41 of 120 patients with prior muscle complaints developed pain on simvastatin 20 mg but not placebo in a blinded crossover. Randomized to add ubiquinol 600 mg/day or placebo for 8 weeks, serum CoQ10 rose from 1.3 to 5.2 mcg/mL, but muscle pain, strength and VO2max did not improve. Marginally more patients reported pain on CoQ10 (14 of 20 versus 7 of 18, p=0.05).

Statin muscle meta-analysis: 12 trials, 575 patients, less muscle pain

Systematic review and meta-analysis

Qu H et al. J Am Heart Assoc. 2018;7(19):e009835. PMID 30371340.

CoQ10 reduced statin-associated muscle pain (WMD -1.60, 95% CI -1.75 to -1.44), weakness, cramps and tiredness versus placebo, without lowering creatine kinase (WMD 0.09, 95% CI -0.06 to 0.24).

Participants / model
575 statin-treated patients across 12 randomized trials
Treatment
Oral CoQ10 versus placebo
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 12 randomized trials
Funding
not stated in the source

Meta-analyses on this question disagree.

Read the original source
Statin myalgia meta-analysis: 7 trials, 321 adults, no benefit

Systematic review and meta-analysis

Kennedy C et al. Atherosclerosis. 2020;299:1-8. PMID 32179207.

The meta-analysis found no benefit of oral CoQ10 on myalgia (WMD -0.42, 95% CI -1.47 to 0.62) and no effect on staying on statin therapy (RR 0.99, 95% CI 0.81 to 1.20). Only 2 of the included trials were positive.

Participants / model
321 adults with statin-associated myalgia across 7 randomized trials
Treatment
Oral CoQ10 versus placebo
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 7 randomized trials
Funding
not stated in the source

Meta-analyses on this question disagree.

Read the original source
Confirmed statin myalgia: 41 patients, ubiquinol raised serum CoQ10, pain unchanged

Randomized controlled trial

Taylor BA et al. Atherosclerosis. 2015;238(2):329-35. PMID 25545331.

Of 120 patients with prior statin muscle complaints, 41 developed pain on simvastatin 20 mg but not placebo in a blinded crossover. Randomized to add CoQ10 or placebo for 8 weeks, serum CoQ10 rose from 1.3 to 5.2 mcg/mL with CoQ10, but muscle pain, strength and VO2max did not improve. Marginally more patients reported pain on CoQ10 (14 of 20 versus 7 of 18, p=0.05).

Participants / model
41 patients with confirmed statin myalgia, from 120 with prior statin muscle complaints
Treatment
Oral ubiquinol 600 mg/day with simvastatin 20 mg/day, or placebo
Follow-up
8 weeks
Study design
Blinded crossover screen followed by a randomized placebo-controlled trial
Funding
not stated in the source

Ubiquinol, the reduced form, was the product tested.

Read the original source

Does CoQ10 improve fatigue or exercise performance?

A pooled analysis found lower fatigue scores, but exercise effects in healthy adults were small and unstable, with very low to low certainty.

A meta-analysis of 13 randomized trials (1,126 healthy and diseased participants) found CoQ10 lowered fatigue scores versus placebo (Hedges' g -0.398, 95% CI -0.641 to -0.155), with larger effects at higher daily doses and longer duration. The effect was significant for CoQ10-only products but not for combination products.

A meta-analysis of 24 randomized trials in healthy adults found CoQ10 consistently raised blood CoQ10, but effects on exercise performance were small and inconsistent. Chronic use showed a small benefit that was not stable after excluding outliers, acute use showed none, and anaerobic and strength outcomes changed little. Certainty was very low to low.

Fatigue meta-analysis: 13 trials, 1,126 participants, lower fatigue scores

Systematic review and meta-analysis

Tsai IC et al. Front Pharmacol. 2022;13:883251. PMID 36091835.

CoQ10 lowered fatigue scores versus placebo (Hedges' g -0.398, 95% CI -0.641 to -0.155), with larger effects at higher daily doses and longer duration. The effect was significant for CoQ10-only products but not for combination products. One gastrointestinal adverse event was reported among 602 CoQ10 recipients.

Participants / model
1,126 healthy and diseased participants across 13 randomized trials
Treatment
Oral CoQ10 versus placebo
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 13 randomized trials
Funding
not stated in the source

Pooled across healthy and diseased groups and across doses.

Read the original source
Exercise meta-analysis: 24 trials in healthy adults, small and inconsistent effects

Systematic review and meta-analysis

Deng H et al. Br J Nutr. 2025:1-21. PMID 41457257.

CoQ10 consistently raised blood CoQ10, but effects on exercise performance were small and inconsistent. Chronic use showed a small benefit that was not stable after excluding outliers, acute use showed none, and anaerobic and strength outcomes changed little. Certainty was very low to low.

Participants / model
Healthy adults across 24 randomized trials
Treatment
Oral CoQ10 versus placebo, acute and chronic
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 24 randomized trials
Funding
not stated in the source

Certainty was very low to low.

Read the original source

What did the Parkinson and Huntington disease studies find?

Both large trials stopped for futility. In 600 people with early Parkinson disease and 609 with early Huntington disease, CoQ10 did not beat placebo.

QE3 randomized 600 people with early Parkinson disease to placebo or CoQ10 1200 or 2400 mg/day (all with vitamin E 1200 IU/day) for up to 16 months. It stopped for futility. Total UPDRS worsened by 6.9 points on placebo, 7.5 on the lower dose and 8.0 on the higher dose.

2CARE randomized 609 people with early Huntington disease to CoQ10 2400 mg/day or placebo with planned 60-month follow-up. A futility analysis (conditional power under 5%) ended it early in July 2014, with no significant differences on primary or secondary outcomes.

QE3: 600 people with early Parkinson disease, stopped for futility

Randomized controlled trial

Beal MF et al. JAMA Neurol. 2014;71(5):543-52. PMID 24664227.

The trial stopped for futility. Total UPDRS worsened by 6.9 points on placebo, 7.5 on the lower CoQ10 dose and 8.0 on the higher dose. CoQ10 was safe and well tolerated at these doses.

Participants / model
600 people with early Parkinson disease
Treatment
Oral CoQ10 1200 or 2400 mg/day, or placebo, all with vitamin E 1200 IU/day
Follow-up
Up to 16 months
Study design
Randomized placebo-controlled trial, stopped for futility
Funding
not stated in the source

Applies to early Parkinson disease; all arms also received vitamin E.

Read the original source
2CARE: 609 people with early Huntington disease, ended for futility

Randomized controlled trial

McGarry A et al. Neurology. 2017;88(2):152-159. PMID 27913695.

A futility analysis (conditional power under 5%) ended the trial early in July 2014, with no significant differences on primary or secondary outcomes. CoQ10 was generally safe and well tolerated.

Participants / model
609 people with early Huntington disease
Treatment
Oral CoQ10 2400 mg/day or placebo
Follow-up
Planned 60-month follow-up; ended early in July 2014
Study design
Randomized placebo-controlled trial, ended for futility
Funding
not stated in the source

Applies to early Huntington disease.

Read the original source

Does oral CoQ10 raise plasma levels but not tissue levels?

Plasma levels rise reliably. In skeletal muscle of 40 older adults, muscle and mitochondrial CoQ10 did not change after 12 weeks, but in 121 cardiac surgery patients levels rose in heart tissue and heart mitochondria after 2 weeks.

The seller framing is that oral CoQ10 raises blood levels but not tissue levels, and that it is commonly taken for energy, mitochondrial support, statin muscle symptoms and heart failure. Blood levels rose in every trial that measured them above.

For skeletal muscle the framing holds in the trial reviewed. In a 12-week double-blind trial in 40 community-dwelling older adults (mean age 74), CoQ10 400 mg/day raised plasma CoQ10, but levels in muscle tissue and isolated muscle mitochondria did not change. Mitochondrial respiratory capacity, H2O2 emission, mitochondrial content, glucose tolerance, VO2max and body composition were also unchanged.

It does not hold for every tissue. In 121 patients randomized to CoQ10 300 mg/day or placebo for 2 weeks before elective cardiac surgery, levels rose in serum, atrial trabeculae and isolated heart mitochondria, mitochondrial efficiency improved, and excised trabeculae tolerated in vitro hypoxia better. Pre- and postoperative hemodynamics and troponin I release did not differ. The heart failure claim rests mainly on one trial, and the statin, energy and mitochondrial claims are mixed or unproven.

Older adults: 40 people, plasma CoQ10 rose, muscle and mitochondrial CoQ10 did not

Randomized controlled trial

Schmücker M et al. Geroscience. 2026;48(6):8049-8063. PMID 41604113.

CoQ10 raised plasma CoQ10, but CoQ10 levels in muscle tissue and isolated muscle mitochondria did not change. Mitochondrial respiratory capacity, H2O2 emission, mitochondrial content, glucose tolerance, VO2max and body composition were also unchanged.

Participants / model
40 community-dwelling older adults (mean age 74)
Treatment
Oral CoQ10 400 mg/day or placebo
Follow-up
12 weeks
Study design
Double-blind randomized trial
Funding
not stated in the source

One author reports consulting for Pharma Nord. The result is for skeletal muscle in older adults.

Read the original source
Cardiac surgery: 121 patients, levels rose in serum, heart tissue and heart mitochondria

Randomized controlled trial

Rosenfeldt F et al. J Thorac Cardiovasc Surg. 2005;129(1):25-32. PMID 15632821.

CoQ10 levels rose in serum, atrial trabeculae and isolated heart mitochondria, mitochondrial efficiency improved, and excised trabeculae tolerated in vitro hypoxia better. Pre- and postoperative hemodynamics and troponin I release did not differ. Heart tissue in this setting did take up CoQ10.

Participants / model
121 patients having elective cardiac surgery
Treatment
Oral CoQ10 300 mg/day or placebo
Follow-up
2 weeks before surgery
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

Heart tissue took up CoQ10 here, so the statement that tissue levels do not rise holds for skeletal muscle in older adults, not for every tissue.

Read the original source
Advanced heart failure: 55 patients, serum CoQ10 doubled, no change in function

Randomized controlled trial

Khatta M et al. Ann Intern Med. 2000;132(8):636-40. PMID 10766682.

CoQ10 raised mean serum CoQ10 from 0.95 to 2.2 mcg/mL, but ejection fraction, peak oxygen consumption and exercise duration did not change versus placebo.

Participants / model
55 patients with NYHA class III to IV heart failure and ejection fraction under 40% on standard therapy (46 completed)
Treatment
Oral CoQ10 200 mg/day or placebo
Follow-up
not stated in the source
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

Applies to patients with advanced heart failure.

Read the original source

How does CoQ10 work, and where does the oral dose go?

The sources reviewed do not describe CoQ10's cell-level action. They show plasma levels rising reliably with oral dosing, no rise in muscle tissue in older adults, and a rise in heart tissue in cardiac surgery patients.

CoQ10 comes in an oxidized form (ubidecarenone, ubiquinone) and a reduced form (ubiquinol), and products sell either. Many trial abstracts do not state the form. In advanced heart failure, 200 mg/day raised mean serum CoQ10 from 0.95 to 2.2 mcg/mL, and in confirmed statin myalgia, ubiquinol 600 mg/day raised it from 1.3 to 5.2 mcg/mL. A meta-analysis of 24 trials in healthy adults found CoQ10 consistently raised blood CoQ10.

Whether the rise reaches tissue depends on the tissue studied. Muscle tissue and isolated muscle mitochondria did not change in 40 older adults after 12 weeks, while heart tissue and isolated heart mitochondria rose in 121 cardiac surgery patients after 2 weeks. Ubiquinol-versus-ubiquinone absorption claims were not tested.

PubChem: coenzyme Q10 and ubiquinol identity

Chemical identity record

National Library of Medicine. PubChem compound records CID 5281915 (coenzyme Q10, ubidecarenone) and CID 9962735 (ubiquinol).

Coenzyme Q10 (ubidecarenone, the oxidized ubiquinone form): C59H90O4, 863.3 g/mol, CAS 303-98-0. Ubiquinol, the reduced form: CID 9962735, C59H92O4, 865.4 g/mol, CAS 992-78-9. Products sell either form in different formulations. Many trial abstracts do not state the form, and blood levels and results should not be pooled across forms without checking.

Participants / model
Chemical identity, not a clinical population
Treatment
Two defined redox forms
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

Identity record only; it says nothing about efficacy or safety. Ubiquinol-versus-ubiquinone absorption claims are not tested here.

Read the original source
Advanced heart failure: 55 patients, serum CoQ10 doubled, no change in function

Randomized controlled trial

Khatta M et al. Ann Intern Med. 2000;132(8):636-40. PMID 10766682.

CoQ10 raised mean serum CoQ10 from 0.95 to 2.2 mcg/mL, but ejection fraction, peak oxygen consumption and exercise duration did not change versus placebo.

Participants / model
55 patients with NYHA class III to IV heart failure and ejection fraction under 40% on standard therapy (46 completed)
Treatment
Oral CoQ10 200 mg/day or placebo
Follow-up
not stated in the source
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

Applies to patients with advanced heart failure.

Read the original source
Confirmed statin myalgia: 41 patients, ubiquinol raised serum CoQ10, pain unchanged

Randomized controlled trial

Taylor BA et al. Atherosclerosis. 2015;238(2):329-35. PMID 25545331.

Of 120 patients with prior statin muscle complaints, 41 developed pain on simvastatin 20 mg but not placebo in a blinded crossover. Randomized to add CoQ10 or placebo for 8 weeks, serum CoQ10 rose from 1.3 to 5.2 mcg/mL with CoQ10, but muscle pain, strength and VO2max did not improve. Marginally more patients reported pain on CoQ10 (14 of 20 versus 7 of 18, p=0.05).

Participants / model
41 patients with confirmed statin myalgia, from 120 with prior statin muscle complaints
Treatment
Oral ubiquinol 600 mg/day with simvastatin 20 mg/day, or placebo
Follow-up
8 weeks
Study design
Blinded crossover screen followed by a randomized placebo-controlled trial
Funding
not stated in the source

Ubiquinol, the reduced form, was the product tested.

Read the original source
Exercise meta-analysis: 24 trials in healthy adults, small and inconsistent effects

Systematic review and meta-analysis

Deng H et al. Br J Nutr. 2025:1-21. PMID 41457257.

CoQ10 consistently raised blood CoQ10, but effects on exercise performance were small and inconsistent. Chronic use showed a small benefit that was not stable after excluding outliers, acute use showed none, and anaerobic and strength outcomes changed little. Certainty was very low to low.

Participants / model
Healthy adults across 24 randomized trials
Treatment
Oral CoQ10 versus placebo, acute and chronic
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 24 randomized trials
Funding
not stated in the source

Certainty was very low to low.

Read the original source
Older adults: 40 people, plasma CoQ10 rose, muscle and mitochondrial CoQ10 did not

Randomized controlled trial

Schmücker M et al. Geroscience. 2026;48(6):8049-8063. PMID 41604113.

CoQ10 raised plasma CoQ10, but CoQ10 levels in muscle tissue and isolated muscle mitochondria did not change. Mitochondrial respiratory capacity, H2O2 emission, mitochondrial content, glucose tolerance, VO2max and body composition were also unchanged.

Participants / model
40 community-dwelling older adults (mean age 74)
Treatment
Oral CoQ10 400 mg/day or placebo
Follow-up
12 weeks
Study design
Double-blind randomized trial
Funding
not stated in the source

One author reports consulting for Pharma Nord. The result is for skeletal muscle in older adults.

Read the original source
Cardiac surgery: 121 patients, levels rose in serum, heart tissue and heart mitochondria

Randomized controlled trial

Rosenfeldt F et al. J Thorac Cardiovasc Surg. 2005;129(1):25-32. PMID 15632821.

CoQ10 levels rose in serum, atrial trabeculae and isolated heart mitochondria, mitochondrial efficiency improved, and excised trabeculae tolerated in vitro hypoxia better. Pre- and postoperative hemodynamics and troponin I release did not differ. Heart tissue in this setting did take up CoQ10.

Participants / model
121 patients having elective cardiac surgery
Treatment
Oral CoQ10 300 mg/day or placebo
Follow-up
2 weeks before surgery
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

Heart tissue took up CoQ10 here, so the statement that tissue levels do not rise holds for skeletal muscle in older adults, not for every tissue.

Read the original source

What side effects and interactions are reported?

CoQ10 at 1200 to 2400 mg/day was reported as safe and well tolerated in two large neurology trials, and adverse events were inconclusive in the Cochrane heart failure review. One 24-patient crossover found no change in warfarin response, though case reports describe reduced response.

In the Parkinson (QE3) and Huntington (2CARE) trials, CoQ10 at 1200 to 2400 mg/day was reported as safe and well tolerated. One gastrointestinal adverse event was reported among 602 CoQ10 recipients in the fatigue meta-analysis, and adverse events were inconclusive in the Cochrane heart failure review (RR 0.70, 95% CI 0.45 to 1.10). In the statin myalgia trial, marginally more patients reported pain on CoQ10 (14 of 20 versus 7 of 18, p=0.05).

Case reports describe reduced warfarin response with CoQ10. In a randomized double-blind crossover in 24 outpatients on stable long-term warfarin, CoQ10 100 mg/day for 4 weeks did not change INR stability or the warfarin dose needed (geometric mean 36.5 mg/week on CoQ10 versus 36.0 on placebo). This is one 24-patient trial and does not settle the question.

QE3: 600 people with early Parkinson disease, stopped for futility

Randomized controlled trial

Beal MF et al. JAMA Neurol. 2014;71(5):543-52. PMID 24664227.

The trial stopped for futility. Total UPDRS worsened by 6.9 points on placebo, 7.5 on the lower CoQ10 dose and 8.0 on the higher dose. CoQ10 was safe and well tolerated at these doses.

Participants / model
600 people with early Parkinson disease
Treatment
Oral CoQ10 1200 or 2400 mg/day, or placebo, all with vitamin E 1200 IU/day
Follow-up
Up to 16 months
Study design
Randomized placebo-controlled trial, stopped for futility
Funding
not stated in the source

Applies to early Parkinson disease; all arms also received vitamin E.

Read the original source
2CARE: 609 people with early Huntington disease, ended for futility

Randomized controlled trial

McGarry A et al. Neurology. 2017;88(2):152-159. PMID 27913695.

A futility analysis (conditional power under 5%) ended the trial early in July 2014, with no significant differences on primary or secondary outcomes. CoQ10 was generally safe and well tolerated.

Participants / model
609 people with early Huntington disease
Treatment
Oral CoQ10 2400 mg/day or placebo
Follow-up
Planned 60-month follow-up; ended early in July 2014
Study design
Randomized placebo-controlled trial, ended for futility
Funding
not stated in the source

Applies to early Huntington disease.

Read the original source
Fatigue meta-analysis: 13 trials, 1,126 participants, lower fatigue scores

Systematic review and meta-analysis

Tsai IC et al. Front Pharmacol. 2022;13:883251. PMID 36091835.

CoQ10 lowered fatigue scores versus placebo (Hedges' g -0.398, 95% CI -0.641 to -0.155), with larger effects at higher daily doses and longer duration. The effect was significant for CoQ10-only products but not for combination products. One gastrointestinal adverse event was reported among 602 CoQ10 recipients.

Participants / model
1,126 healthy and diseased participants across 13 randomized trials
Treatment
Oral CoQ10 versus placebo
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 13 randomized trials
Funding
not stated in the source

Pooled across healthy and diseased groups and across doses.

Read the original source
Cochrane review: 11 trials, 1573 participants, no convincing evidence either way

Systematic review and meta-analysis

Al Saadi T et al. Cochrane Database Syst Rev. 2021;(2)(2):CD008684. PMID 35608922.

The review found moderate-quality evidence that CoQ10 probably reduces all-cause mortality (RR 0.58, 95% CI 0.35 to 0.95), an estimate drawn from 1 study of 420 participants, and heart failure hospitalization (RR 0.62, 95% CI 0.49 to 0.78; 2 studies, 1061 participants). Effects on ejection fraction (very low quality) and exercise capacity were uncertain, and adverse events were inconclusive (RR 0.70, 95% CI 0.45 to 1.10). The authors state there is no convincing evidence to support or refute CoQ10 for heart failure.

Participants / model
People with heart failure across 11 randomized trials (1573 participants, all with unclear or high risk of bias in at least one domain)
Treatment
CoQ10 at varying doses versus placebo or conventional therapy
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 11 randomized trials
Funding
not stated in the source

The mortality estimate comes from a single trial of 420 participants.

Read the original source
Confirmed statin myalgia: 41 patients, ubiquinol raised serum CoQ10, pain unchanged

Randomized controlled trial

Taylor BA et al. Atherosclerosis. 2015;238(2):329-35. PMID 25545331.

Of 120 patients with prior statin muscle complaints, 41 developed pain on simvastatin 20 mg but not placebo in a blinded crossover. Randomized to add CoQ10 or placebo for 8 weeks, serum CoQ10 rose from 1.3 to 5.2 mcg/mL with CoQ10, but muscle pain, strength and VO2max did not improve. Marginally more patients reported pain on CoQ10 (14 of 20 versus 7 of 18, p=0.05).

Participants / model
41 patients with confirmed statin myalgia, from 120 with prior statin muscle complaints
Treatment
Oral ubiquinol 600 mg/day with simvastatin 20 mg/day, or placebo
Follow-up
8 weeks
Study design
Blinded crossover screen followed by a randomized placebo-controlled trial
Funding
not stated in the source

Ubiquinol, the reduced form, was the product tested.

Read the original source
Warfarin crossover: 24 outpatients, no change in INR stability or warfarin dose

Randomized controlled trial

Engelsen J et al. Ugeskr Laeger. 2003;165(18):1868-71. PMID 12772396.

Case reports describe reduced warfarin response with CoQ10. In this randomized crossover, CoQ10 did not change INR stability or the warfarin dose needed (geometric mean 36.5 mg/week on CoQ10 versus 36.0 on placebo).

Participants / model
24 outpatients on stable long-term warfarin
Treatment
Oral CoQ10 100 mg/day or placebo, in 4-week periods
Follow-up
4-week periods
Study design
Randomized double-blind placebo-controlled crossover trial
Funding
not stated in the source

One 24-patient crossover trial; it does not settle the question.

Read the original source

Why does coenzyme Q10 sit in B tier?

Blood levels rise reliably and one 420-patient trial reported fewer cardiovascular events in heart failure, but most other outcomes are inconsistent or negative.

The B reflects a supplement with a reliable rise in blood levels and one positive heart failure trial that drives the Cochrane review's moderate-quality mortality estimate. Everything else is inconsistent: statin-muscle meta-analyses disagree and the best-controlled statin trial was negative, two large neurology trials (600 and 609 patients) stopped for futility, exercise effects in healthy adults are small and unstable, and muscle CoQ10 and mitochondrial function did not change in older adults.

On the seller framing, plasma rises while tissue does not holds for skeletal muscle in the trial reviewed but not for heart tissue in cardiac surgery patients. The heart failure claim rests mainly on one trial, and the statin, energy and mitochondrial claims are mixed or unproven.

Q-SYMBIO: 420 patients with heart failure, 2 years, fewer major cardiovascular events

Randomized controlled trial

Mortensen SA et al. JACC Heart Fail. 2014;2(6):641-9. PMID 25282031.

The 16-week endpoints (NYHA class, 6-minute walk, NT-proBNP) did not change. The 2-year composite of major adverse cardiovascular events occurred in 15% versus 26% (HR 0.50, 95% CI 0.32 to 0.80), with lower cardiovascular mortality (9% versus 16%) and all-cause mortality (10% versus 18%).

Participants / model
420 patients with moderate to severe chronic heart failure
Treatment
Oral CoQ10 100 mg three times daily or placebo, on top of standard therapy
Follow-up
2 years
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

This is one trial. It drives the Cochrane review's moderate-quality mortality estimate.

Read the original source
Cochrane review: 11 trials, 1573 participants, no convincing evidence either way

Systematic review and meta-analysis

Al Saadi T et al. Cochrane Database Syst Rev. 2021;(2)(2):CD008684. PMID 35608922.

The review found moderate-quality evidence that CoQ10 probably reduces all-cause mortality (RR 0.58, 95% CI 0.35 to 0.95), an estimate drawn from 1 study of 420 participants, and heart failure hospitalization (RR 0.62, 95% CI 0.49 to 0.78; 2 studies, 1061 participants). Effects on ejection fraction (very low quality) and exercise capacity were uncertain, and adverse events were inconclusive (RR 0.70, 95% CI 0.45 to 1.10). The authors state there is no convincing evidence to support or refute CoQ10 for heart failure.

Participants / model
People with heart failure across 11 randomized trials (1573 participants, all with unclear or high risk of bias in at least one domain)
Treatment
CoQ10 at varying doses versus placebo or conventional therapy
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 11 randomized trials
Funding
not stated in the source

The mortality estimate comes from a single trial of 420 participants.

Read the original source
Statin muscle meta-analysis: 12 trials, 575 patients, less muscle pain

Systematic review and meta-analysis

Qu H et al. J Am Heart Assoc. 2018;7(19):e009835. PMID 30371340.

CoQ10 reduced statin-associated muscle pain (WMD -1.60, 95% CI -1.75 to -1.44), weakness, cramps and tiredness versus placebo, without lowering creatine kinase (WMD 0.09, 95% CI -0.06 to 0.24).

Participants / model
575 statin-treated patients across 12 randomized trials
Treatment
Oral CoQ10 versus placebo
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 12 randomized trials
Funding
not stated in the source

Meta-analyses on this question disagree.

Read the original source
Statin myalgia meta-analysis: 7 trials, 321 adults, no benefit

Systematic review and meta-analysis

Kennedy C et al. Atherosclerosis. 2020;299:1-8. PMID 32179207.

The meta-analysis found no benefit of oral CoQ10 on myalgia (WMD -0.42, 95% CI -1.47 to 0.62) and no effect on staying on statin therapy (RR 0.99, 95% CI 0.81 to 1.20). Only 2 of the included trials were positive.

Participants / model
321 adults with statin-associated myalgia across 7 randomized trials
Treatment
Oral CoQ10 versus placebo
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 7 randomized trials
Funding
not stated in the source

Meta-analyses on this question disagree.

Read the original source
QE3: 600 people with early Parkinson disease, stopped for futility

Randomized controlled trial

Beal MF et al. JAMA Neurol. 2014;71(5):543-52. PMID 24664227.

The trial stopped for futility. Total UPDRS worsened by 6.9 points on placebo, 7.5 on the lower CoQ10 dose and 8.0 on the higher dose. CoQ10 was safe and well tolerated at these doses.

Participants / model
600 people with early Parkinson disease
Treatment
Oral CoQ10 1200 or 2400 mg/day, or placebo, all with vitamin E 1200 IU/day
Follow-up
Up to 16 months
Study design
Randomized placebo-controlled trial, stopped for futility
Funding
not stated in the source

Applies to early Parkinson disease; all arms also received vitamin E.

Read the original source
2CARE: 609 people with early Huntington disease, ended for futility

Randomized controlled trial

McGarry A et al. Neurology. 2017;88(2):152-159. PMID 27913695.

A futility analysis (conditional power under 5%) ended the trial early in July 2014, with no significant differences on primary or secondary outcomes. CoQ10 was generally safe and well tolerated.

Participants / model
609 people with early Huntington disease
Treatment
Oral CoQ10 2400 mg/day or placebo
Follow-up
Planned 60-month follow-up; ended early in July 2014
Study design
Randomized placebo-controlled trial, ended for futility
Funding
not stated in the source

Applies to early Huntington disease.

Read the original source
Exercise meta-analysis: 24 trials in healthy adults, small and inconsistent effects

Systematic review and meta-analysis

Deng H et al. Br J Nutr. 2025:1-21. PMID 41457257.

CoQ10 consistently raised blood CoQ10, but effects on exercise performance were small and inconsistent. Chronic use showed a small benefit that was not stable after excluding outliers, acute use showed none, and anaerobic and strength outcomes changed little. Certainty was very low to low.

Participants / model
Healthy adults across 24 randomized trials
Treatment
Oral CoQ10 versus placebo, acute and chronic
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 24 randomized trials
Funding
not stated in the source

Certainty was very low to low.

Read the original source
Older adults: 40 people, plasma CoQ10 rose, muscle and mitochondrial CoQ10 did not

Randomized controlled trial

Schmücker M et al. Geroscience. 2026;48(6):8049-8063. PMID 41604113.

CoQ10 raised plasma CoQ10, but CoQ10 levels in muscle tissue and isolated muscle mitochondria did not change. Mitochondrial respiratory capacity, H2O2 emission, mitochondrial content, glucose tolerance, VO2max and body composition were also unchanged.

Participants / model
40 community-dwelling older adults (mean age 74)
Treatment
Oral CoQ10 400 mg/day or placebo
Follow-up
12 weeks
Study design
Double-blind randomized trial
Funding
not stated in the source

One author reports consulting for Pharma Nord. The result is for skeletal muscle in older adults.

Read the original source

Studies and sources

PubChem: coenzyme Q10 and ubiquinol identity

Chemical identity record

National Library of Medicine. PubChem compound records CID 5281915 (coenzyme Q10, ubidecarenone) and CID 9962735 (ubiquinol).

Coenzyme Q10 (ubidecarenone, the oxidized ubiquinone form): C59H90O4, 863.3 g/mol, CAS 303-98-0. Ubiquinol, the reduced form: CID 9962735, C59H92O4, 865.4 g/mol, CAS 992-78-9. Products sell either form in different formulations. Many trial abstracts do not state the form, and blood levels and results should not be pooled across forms without checking.

Participants / model
Chemical identity, not a clinical population
Treatment
Two defined redox forms
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

Identity record only; it says nothing about efficacy or safety. Ubiquinol-versus-ubiquinone absorption claims are not tested here.

Read the original source
openFDA query, 9 October 2026: no CoQ10 application

Regulatory record

U.S. Food and Drug Administration. openFDA Drugs@FDA query for ubidecarenone, coenzyme Q10 or ubiquinol (brand, generic and active-ingredient fields), run on 9 October 2026.

The query returned no application, so no FDA-approved CoQ10 drug was located. The Cochrane heart failure review describes CoQ10 as a non-prescription nutritional supplement.

Participants / model
FDA application database, not a clinical population
Treatment
Exact substance-name query
Follow-up
Query run on 9 October 2026
Study design
Dated US approval-record query
Funding
not stated in the source

A negative query on one date is not proof about every product or jurisdiction. Approvals outside the United States were not examined.

Read the original source
Q-SYMBIO: 420 patients with heart failure, 2 years, fewer major cardiovascular events

Randomized controlled trial

Mortensen SA et al. JACC Heart Fail. 2014;2(6):641-9. PMID 25282031.

The 16-week endpoints (NYHA class, 6-minute walk, NT-proBNP) did not change. The 2-year composite of major adverse cardiovascular events occurred in 15% versus 26% (HR 0.50, 95% CI 0.32 to 0.80), with lower cardiovascular mortality (9% versus 16%) and all-cause mortality (10% versus 18%).

Participants / model
420 patients with moderate to severe chronic heart failure
Treatment
Oral CoQ10 100 mg three times daily or placebo, on top of standard therapy
Follow-up
2 years
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

This is one trial. It drives the Cochrane review's moderate-quality mortality estimate.

Read the original source
Cochrane review: 11 trials, 1573 participants, no convincing evidence either way

Systematic review and meta-analysis

Al Saadi T et al. Cochrane Database Syst Rev. 2021;(2)(2):CD008684. PMID 35608922.

The review found moderate-quality evidence that CoQ10 probably reduces all-cause mortality (RR 0.58, 95% CI 0.35 to 0.95), an estimate drawn from 1 study of 420 participants, and heart failure hospitalization (RR 0.62, 95% CI 0.49 to 0.78; 2 studies, 1061 participants). Effects on ejection fraction (very low quality) and exercise capacity were uncertain, and adverse events were inconclusive (RR 0.70, 95% CI 0.45 to 1.10). The authors state there is no convincing evidence to support or refute CoQ10 for heart failure.

Participants / model
People with heart failure across 11 randomized trials (1573 participants, all with unclear or high risk of bias in at least one domain)
Treatment
CoQ10 at varying doses versus placebo or conventional therapy
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 11 randomized trials
Funding
not stated in the source

The mortality estimate comes from a single trial of 420 participants.

Read the original source
Advanced heart failure: 55 patients, serum CoQ10 doubled, no change in function

Randomized controlled trial

Khatta M et al. Ann Intern Med. 2000;132(8):636-40. PMID 10766682.

CoQ10 raised mean serum CoQ10 from 0.95 to 2.2 mcg/mL, but ejection fraction, peak oxygen consumption and exercise duration did not change versus placebo.

Participants / model
55 patients with NYHA class III to IV heart failure and ejection fraction under 40% on standard therapy (46 completed)
Treatment
Oral CoQ10 200 mg/day or placebo
Follow-up
not stated in the source
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

Applies to patients with advanced heart failure.

Read the original source
Statin muscle meta-analysis: 12 trials, 575 patients, less muscle pain

Systematic review and meta-analysis

Qu H et al. J Am Heart Assoc. 2018;7(19):e009835. PMID 30371340.

CoQ10 reduced statin-associated muscle pain (WMD -1.60, 95% CI -1.75 to -1.44), weakness, cramps and tiredness versus placebo, without lowering creatine kinase (WMD 0.09, 95% CI -0.06 to 0.24).

Participants / model
575 statin-treated patients across 12 randomized trials
Treatment
Oral CoQ10 versus placebo
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 12 randomized trials
Funding
not stated in the source

Meta-analyses on this question disagree.

Read the original source
Statin myalgia meta-analysis: 7 trials, 321 adults, no benefit

Systematic review and meta-analysis

Kennedy C et al. Atherosclerosis. 2020;299:1-8. PMID 32179207.

The meta-analysis found no benefit of oral CoQ10 on myalgia (WMD -0.42, 95% CI -1.47 to 0.62) and no effect on staying on statin therapy (RR 0.99, 95% CI 0.81 to 1.20). Only 2 of the included trials were positive.

Participants / model
321 adults with statin-associated myalgia across 7 randomized trials
Treatment
Oral CoQ10 versus placebo
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 7 randomized trials
Funding
not stated in the source

Meta-analyses on this question disagree.

Read the original source
Confirmed statin myalgia: 41 patients, ubiquinol raised serum CoQ10, pain unchanged

Randomized controlled trial

Taylor BA et al. Atherosclerosis. 2015;238(2):329-35. PMID 25545331.

Of 120 patients with prior statin muscle complaints, 41 developed pain on simvastatin 20 mg but not placebo in a blinded crossover. Randomized to add CoQ10 or placebo for 8 weeks, serum CoQ10 rose from 1.3 to 5.2 mcg/mL with CoQ10, but muscle pain, strength and VO2max did not improve. Marginally more patients reported pain on CoQ10 (14 of 20 versus 7 of 18, p=0.05).

Participants / model
41 patients with confirmed statin myalgia, from 120 with prior statin muscle complaints
Treatment
Oral ubiquinol 600 mg/day with simvastatin 20 mg/day, or placebo
Follow-up
8 weeks
Study design
Blinded crossover screen followed by a randomized placebo-controlled trial
Funding
not stated in the source

Ubiquinol, the reduced form, was the product tested.

Read the original source
Fatigue meta-analysis: 13 trials, 1,126 participants, lower fatigue scores

Systematic review and meta-analysis

Tsai IC et al. Front Pharmacol. 2022;13:883251. PMID 36091835.

CoQ10 lowered fatigue scores versus placebo (Hedges' g -0.398, 95% CI -0.641 to -0.155), with larger effects at higher daily doses and longer duration. The effect was significant for CoQ10-only products but not for combination products. One gastrointestinal adverse event was reported among 602 CoQ10 recipients.

Participants / model
1,126 healthy and diseased participants across 13 randomized trials
Treatment
Oral CoQ10 versus placebo
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 13 randomized trials
Funding
not stated in the source

Pooled across healthy and diseased groups and across doses.

Read the original source
Exercise meta-analysis: 24 trials in healthy adults, small and inconsistent effects

Systematic review and meta-analysis

Deng H et al. Br J Nutr. 2025:1-21. PMID 41457257.

CoQ10 consistently raised blood CoQ10, but effects on exercise performance were small and inconsistent. Chronic use showed a small benefit that was not stable after excluding outliers, acute use showed none, and anaerobic and strength outcomes changed little. Certainty was very low to low.

Participants / model
Healthy adults across 24 randomized trials
Treatment
Oral CoQ10 versus placebo, acute and chronic
Follow-up
Varied by included trial
Study design
Systematic review and meta-analysis of 24 randomized trials
Funding
not stated in the source

Certainty was very low to low.

Read the original source
Older adults: 40 people, plasma CoQ10 rose, muscle and mitochondrial CoQ10 did not

Randomized controlled trial

Schmücker M et al. Geroscience. 2026;48(6):8049-8063. PMID 41604113.

CoQ10 raised plasma CoQ10, but CoQ10 levels in muscle tissue and isolated muscle mitochondria did not change. Mitochondrial respiratory capacity, H2O2 emission, mitochondrial content, glucose tolerance, VO2max and body composition were also unchanged.

Participants / model
40 community-dwelling older adults (mean age 74)
Treatment
Oral CoQ10 400 mg/day or placebo
Follow-up
12 weeks
Study design
Double-blind randomized trial
Funding
not stated in the source

One author reports consulting for Pharma Nord. The result is for skeletal muscle in older adults.

Read the original source
Cardiac surgery: 121 patients, levels rose in serum, heart tissue and heart mitochondria

Randomized controlled trial

Rosenfeldt F et al. J Thorac Cardiovasc Surg. 2005;129(1):25-32. PMID 15632821.

CoQ10 levels rose in serum, atrial trabeculae and isolated heart mitochondria, mitochondrial efficiency improved, and excised trabeculae tolerated in vitro hypoxia better. Pre- and postoperative hemodynamics and troponin I release did not differ. Heart tissue in this setting did take up CoQ10.

Participants / model
121 patients having elective cardiac surgery
Treatment
Oral CoQ10 300 mg/day or placebo
Follow-up
2 weeks before surgery
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

Heart tissue took up CoQ10 here, so the statement that tissue levels do not rise holds for skeletal muscle in older adults, not for every tissue.

Read the original source
QE3: 600 people with early Parkinson disease, stopped for futility

Randomized controlled trial

Beal MF et al. JAMA Neurol. 2014;71(5):543-52. PMID 24664227.

The trial stopped for futility. Total UPDRS worsened by 6.9 points on placebo, 7.5 on the lower CoQ10 dose and 8.0 on the higher dose. CoQ10 was safe and well tolerated at these doses.

Participants / model
600 people with early Parkinson disease
Treatment
Oral CoQ10 1200 or 2400 mg/day, or placebo, all with vitamin E 1200 IU/day
Follow-up
Up to 16 months
Study design
Randomized placebo-controlled trial, stopped for futility
Funding
not stated in the source

Applies to early Parkinson disease; all arms also received vitamin E.

Read the original source
2CARE: 609 people with early Huntington disease, ended for futility

Randomized controlled trial

McGarry A et al. Neurology. 2017;88(2):152-159. PMID 27913695.

A futility analysis (conditional power under 5%) ended the trial early in July 2014, with no significant differences on primary or secondary outcomes. CoQ10 was generally safe and well tolerated.

Participants / model
609 people with early Huntington disease
Treatment
Oral CoQ10 2400 mg/day or placebo
Follow-up
Planned 60-month follow-up; ended early in July 2014
Study design
Randomized placebo-controlled trial, ended for futility
Funding
not stated in the source

Applies to early Huntington disease.

Read the original source
Warfarin crossover: 24 outpatients, no change in INR stability or warfarin dose

Randomized controlled trial

Engelsen J et al. Ugeskr Laeger. 2003;165(18):1868-71. PMID 12772396.

Case reports describe reduced warfarin response with CoQ10. In this randomized crossover, CoQ10 did not change INR stability or the warfarin dose needed (geometric mean 36.5 mg/week on CoQ10 versus 36.0 on placebo).

Participants / model
24 outpatients on stable long-term warfarin
Treatment
Oral CoQ10 100 mg/day or placebo, in 4-week periods
Follow-up
4-week periods
Study design
Randomized double-blind placebo-controlled crossover trial
Funding
not stated in the source

One 24-patient crossover trial; it does not settle the question.

Read the original source

Why is Coenzyme Q10 in B tier?

B fits a supplement with a real, reliable effect on blood levels and one positive heart failure trial, but with outcomes that do not consistently follow. Meta-analyses disagree on statin muscle symptoms, two large neurology trials stopped for futility, and exercise effects in healthy adults are small and unstable.