CoQ10 and Ubiquinol for Cognition: What a New Randomized Trial Found
A 2026 randomized trial from Swinburne University and the Baker Heart & Diabetes Institute tested 200 mg/day of ubiquinol against placebo in 111 older adults. Here is what it found on memory, processing speed, blood pressure, and arterial stiffness, and how it fits the mixed prior evidence.
Research context: This article discusses a peer-reviewed randomized controlled trial and a companion literature review. It is intended for informational and educational purposes only and does not constitute medical advice. Consult a qualified healthcare professional before making changes to diet, lifestyle, or supplementation.
A well-funded, well-designed trial just returned a negative result
Coenzyme Q10 (CoQ10) and its reduced form, ubiquinol, have been sold for years on a plausible story: mitochondrial antioxidant levels fall with age, CoQ10 is concentrated in the mitochondrial inner membrane where it helps generate ATP, and animal studies have linked supplementation to lower markers of oxidative stress and improved cerebral blood flow. What has been missing is a large, well-controlled human trial testing whether any of that translates into measurable cognitive benefit in older adults. A team based at Swinburne University's Centre for Mental Health and Brain Sciences, working with the Baker Heart & Diabetes Institute and Monash University, ran exactly that trial, registered it years in advance, and published the results in June 2026. The study was funded by Kaneka, the Japanese manufacturer of the Kaneka Ubiquinol™ product tested, which makes the result more rather than less notable: the funder's own product failed to beat placebo on the trial's primary cognitive outcomes (Nankivell MC, Rosenfeldt F, Reddan JM, et al., "Effect of Ubiquinol on Cognitive Function, Blood Pressure, Arterial Stiffness, and Biomarkers of Oxidative Stress and Inflammation in the Elderly: A Randomized Trial," Antioxidants 2026;15(7):806, PMID: 42510537).
What CoQ10 and ubiquinol are supposed to do
CoQ10 is a fat-soluble compound synthesized in the body and concentrated in mitochondria, where it shuttles electrons through the respiratory chain during ATP production and also acts as an antioxidant. Ubiquinol is its reduced, more bioavailable form. Endogenous CoQ10 synthesis declines with age, which is the starting premise for supplementing it in older adults. The proposed routes from CoQ10 to cognition, summarized by the same Swinburne-based research group in a companion review published a few months before their trial, include reduced oxidative stress and neuroinflammation shown in animal models, improved cerebral blood flow and endothelial function in some human studies, and a general case that the aging brain's reduced ATP production and increased oxidative burden are targets CoQ10 is positioned to address (Nankivell MC, Rosenfeldt F, Pipingas A, et al., "Coenzyme Q10 and Cognition: A Review," Nutrients 2025;17(17):2896, PMID: 40944284). That same oxidative-stress-and-ATP framing runs through other compounds covered in our mitochondria and cognitive performance overview, and CoQ10 is frequently stacked alongside PQQ on that basis, a pairing discussed in our PQQ and mitochondrial biogenesis review.
The literature going in was already mixed
The September 2025 review from the same group did not oversell the existing evidence. Scanning animal studies and human clinical trials, the authors reported that twelve studies overall showed improved cognitive function and two showed reduced oxidative stress with CoQ10, either alone or combined with other compounds. Narrowed to the eight human clinical trials specifically, two in healthy adults and six in disease populations, only four found a cognitive benefit and two found increased cerebral blood flow without necessarily showing a cognitive effect. The review's own conclusion was that the literature "presents mixed results, with many human clinical trials also reporting no benefit of CoQ10 supplementation on cognitive performance," and it called for future trials using a wider range of cognitive assessments (Nankivell et al., 2025, PMID: 40944284). That review functioned, in effect, as the rationale and literature setup for the randomized trial the same team then published.
The 2026 trial: design and numbers
The trial randomized 111 adults aged 60 and over (61 to ubiquinol, 50 to placebo; mean age 67.6 in the ubiquinol group and 68.7 in the placebo group) to 90 days of 200 mg/day of Kaneka Ubiquinol™ (two 100 mg capsules daily) or matching placebo. It was prospectively registered with the Australian New Zealand Clinical Trials Registry (ACTRN12618001841268) in November 2018, well before data collection, which limits the risk of outcome-switching that affects some supplement trials. By the end of the 90 days, plasma CoQ10 in the ubiquinol group was roughly four times that of the placebo group (3,867.9 vs 960.8 nmol/L, p < 0.001), confirming the supplement was absorbed and biologically active at the blood level.
Cognition was assessed with a battery covering memory (Verbal Paired Associates, Logical Memory, the Rey Auditory Verbal Learning Test) and processing speed and attention (Digit Span, the Digit Symbol Substitution Test, Trail Making Test A and B, Inspection Time), reduced via principal component analysis into two primary composite scores: memory and processing time. On both composites, the trial found no statistically significant difference between groups after controlling for baseline scores and demographics. Memory composite: ubiquinol estimated marginal mean 0.03 versus placebo 0.12 (F = 0.68, p = 0.41, mean difference -0.09, 95% CI -0.32 to 0.13, eta-squared 0.01). Processing-time composite: ubiquinol 0.18 versus placebo 0.21 (F = 0.08, p = 0.78, mean difference -0.03, 95% CI -0.24 to 0.18, eta-squared near zero). Of the individual subtests, only Digit Span showed a significant group difference (p = 0.005), and it favored placebo, not ubiquinol.
Cardiovascular outcomes, a secondary focus given CoQ10's proposed vascular mechanism, were equally flat: brachial systolic blood pressure (129.6 vs 128.5 mmHg, p = 0.51), brachial diastolic (p = 0.98), aortic systolic (118.6 vs 117.8 mmHg, p = 0.63), carotid-femoral pulse wave velocity, a standard arterial stiffness measure (11.80 vs 11.94 m/s, p = 0.63), and augmentation index (26.7% vs 27.6%, p = 0.52) showed no group differences. Blood biomarkers of oxidative stress and inflammation likewise showed no significant between-group differences at 90 days.
A secondary signal that needs the same caution the authors gave it
The trial did report one positive association, and it is worth stating precisely rather than letting it overshadow the primary null result. Within the ubiquinol group only, a post hoc regression found that a larger rise in plasma CoQ10 over the 90 days predicted better memory composite scores at the final visit (beta = 0.08, 95% CI 0.01 to 0.16, p = 0.03), and a larger reduction in a blood marker of oxidative stress (d-ROMs) also predicted better memory in that group (beta = -1.54, 95% CI -2.98 to -0.09, p = 0.04). No equivalent association was tested or found in the placebo group, since placebo participants did not have meaningfully rising CoQ10 levels to regress against. These are exploratory, within-group, non-prespecified analyses in a trial whose prespecified primary comparisons were negative. They are a hypothesis for a future, adequately powered trial to test directly, not evidence that ubiquinol improved memory in this one.
Why the authors think the trial came back negative, and what that means for the marketing claim
The authors offer several candidate explanations rather than treating the null result as the final word. Participants were healthy older adults who were not screened for mild cognitive impairment, had relatively low baseline oxidative stress, and did not have elevated blood pressure, which narrows the room for a supplement to show benefit on any of those measures. The 90-day duration may be too short; the authors explicitly suggest future trials of 18 months or longer. The study also switched its planned repeated-measures analysis to an ANCOVA after fewer participants completed every assessment than expected, a deviation from the original statistical plan that the authors disclose rather than obscure. Adverse events were similar between groups (71 in the ubiquinol arm versus 73 on placebo), with no events judged probably or highly probably treatment-related, so the trial does not raise a safety signal, it raises an efficacy question.
None of that changes what the trial actually measured: in 111 generally healthy older adults given a bioavailability-confirmed dose of ubiquinol for three months, there was no detectable benefit to memory, processing speed, blood pressure, or arterial stiffness compared to placebo. That is a materially different claim from "CoQ10 doesn't work for anyone," and a materially different claim from the general cognitive-enhancement framing that ubiquinol often carries in supplement marketing aimed at healthy adults, which this trial's population most closely resembles.
Dosing and safety context from the trial
The tested protocol was 200 mg/day of ubiquinol (Kaneka Ubiquinol™, as two 100 mg capsules) for 90 days, the dose and duration most directly supported by this trial's safety data. Adverse events were balanced across groups and none were judged probably related to treatment, consistent with ubiquinol's general reputation for tolerability in trials at this dose range. This describes what was studied, not a dosing recommendation, and it says nothing about doses, durations, or populations the trial did not test, including people already diagnosed with cognitive impairment or cardiovascular disease.
Key takeaways
A June 2026 randomized controlled trial of 111 adults aged 60 and over found that 90 days of 200 mg/day ubiquinol produced no significant improvement over placebo on composite memory or processing-speed scores, nor on blood pressure, arterial stiffness, or oxidative stress and inflammation biomarkers, despite confirmed four-fold higher plasma CoQ10 levels in the treatment group. The trial was funded by the product's manufacturer, Kaneka, which makes the negative primary result more credible rather than less. A companion review by the same research group, published months earlier, had already characterized the broader CoQ10-cognition literature as mixed, with roughly half of prior human trials showing a benefit and half showing none. A secondary, exploratory finding linked within-group rises in plasma CoQ10 to better memory scores in the ubiquinol arm, but this was a post hoc, non-prespecified analysis that the authors themselves frame as hypothesis-generating for future, longer, better-targeted trials, not as evidence that ubiquinol improves memory in healthy older adults.
FAQ
Does this trial mean CoQ10 or ubiquinol does nothing for the brain?
It means that in this specific trial, 200 mg/day of ubiquinol for 90 days produced no significant benefit over placebo on memory, processing speed, blood pressure, or arterial stiffness in generally healthy adults aged 60 and over. The authors note the sample was healthy with low baseline oxidative stress and blood pressure, which narrows the room to detect benefit, and they call for longer trials, 18 months or more, in people with a higher risk of cognitive decline. It does not establish that ubiquinol has no effect in other populations or durations that have not been tested this rigorously.
Why does it matter that Kaneka funded the trial?
Kaneka manufactures the Kaneka Ubiquinol™ product tested and funded the study, including covering its publication costs. A sponsor-funded trial that still reports a negative primary result for the sponsor's own product is generally considered more credible than a positive result would be in the same circumstances, since it works against the funder's commercial interest. The authors state the funder had no role in study design, data analysis, or the decision to publish.
What was the one positive finding in the trial?
A post hoc regression found that, within the ubiquinol group only, a larger increase in plasma CoQ10 over the 90 days was associated with better memory scores at the end of the trial, and a larger drop in a blood marker of oxidative stress was associated with better memory in the same group. This was an exploratory analysis run after the fact, not one of the trial's prespecified primary outcomes, and no equivalent comparison was possible in the placebo group. It is a lead for future research, not a demonstrated treatment effect.
How does this fit with older CoQ10 research?
A 2025 review by the same research group examined prior animal and human studies and found a genuinely mixed picture: of eight human clinical trials, half showed some cognitive benefit and half did not, with inconsistent testing methods across studies cited as one likely reason for the disparity. The 2026 trial is the largest and most rigorously prespecified randomized trial in this specific population, healthy older adults, published to date, and its negative result is consistent with, rather than a dramatic reversal of, that earlier mixed picture.
Primary sources: Nankivell MC, Rosenfeldt F, Reddan JM, de Haan JB, Zhang Ping C, Campbell-Brown B, Pipingas A, Pase MP, Ou R, Cooke MB, Hare DL, Stough C. "Effect of Ubiquinol on Cognitive Function, Blood Pressure, Arterial Stiffness, and Biomarkers of Oxidative Stress and Inflammation in the Elderly: A Randomized Trial." Antioxidants 2026;15(7):806. DOI: 10.3390/antiox15070806. PMID: 42510537. Trial registration: ACTRN12618001841268. Nankivell MC, Rosenfeldt F, Pipingas A, Pase MP, Reddan JM, Stough C. "Coenzyme Q10 and Cognition: A Review." Nutrients 2025;17(17):2896. DOI: 10.3390/nu17172896. PMID: 40944284. This article summarizes published, peer-reviewed research and is not a substitute for individualized medical advice.
Disclaimer
This article is for educational and research-context purposes only. It does not constitute medical advice and is not a substitute for consultation with a qualified healthcare practitioner. The trial and review discussed reflect published, peer-reviewed findings, not personalized clinical guidance. Always consult a doctor before beginning, modifying, or stopping any supplement, particularly if you have a diagnosed cardiovascular or cognitive condition, are pregnant or breastfeeding, or take prescription medications.