Benefits
Cellular energy
Coenzyme Q10 carries electrons in the mitochondrial chain that makes ATP, the cell's energy currency. In a 12-week placebo-controlled trial in 43 people with chronic fatigue syndrome (31 finished), 150 mg a day of ubiquinol improved several symptoms, according to the authors. It was a single small trial, and the abstract does not give effect sizes.
Raises blood ubiquinol levels
In single-blind, placebo-controlled studies run by Kaneka in healthy volunteers, single doses of 150 or 300 mg and 4 weeks of 90, 150 or 300 mg a day raised blood ubiquinol in a dose-related way, with no clinically relevant changes in lab tests, vital signs or ECG.
Egg and sperm research
Ubiquinol is studied for egg and sperm quality because these cells use a lot of energy and are sensitive to oxidative stress. A review commissioned by Kaneka relies mainly on before-and-after studies and on mixtures with other ingredients, and the one placebo-controlled trial of ubiquinol alone in men now carries a journal expression of concern. Benefits for conception are not established.
Mechanism of action
Reduced form
Ubiquinol is coenzyme Q10 in its electron-rich (reduced) state, the form that acts as an antioxidant. The body converts between ubiquinone and ubiquinol, and no trial cited here compares the two forms for any health outcome.
Mitochondrial electron transport
Coenzyme Q10 shuttles electrons in the mitochondrial chain that generates ATP, the cell's energy currency.
Clinical trials
8-week open-label study (20 patients) followed by a 12-week randomized, double-blind, placebo-controlled trial of 150 mg ubiquinol-10 a day. The abstract does not name the ubiquinol brand. (Fukuda et al. 2016, Biofactors)
43 adults with chronic fatigue syndrome in the controlled trial (31 completed: 17 ubiquinol, 14 placebo).
The authors report that 12 weeks of ubiquinol improved several symptoms, including measures of autonomic nervous function and cognitive function named in the title. The abstract does not give effect sizes, and the trial was small with about a quarter of participants not finishing.
Single-blind, placebo-controlled studies of single doses (150 or 300 mg) and 4-week dosing (90, 150 or 300 mg a day) of Kaneka QH ubiquinol, run by Kaneka scientists. (Hosoe et al. 2007, Regul Toxicol Pharmacol)
Healthy volunteers.
Blood ubiquinol rose with dose, leveling off by day 14 at about 2.6, 3.7 and 6.5 micrograms/mL for 90, 150 and 300 mg a day. No clinically relevant changes in lab tests, physical exams, vital signs or ECG were seen. This study measured safety and absorption, not health benefits.
Narrative position paper summarizing ubiquinol research on fertility; the lead author was commissioned by Kaneka to write it. (Derbyshire et al. 2026, Nutrients)
Evidence review; no new participants.
The review argues that ubiquinol may support sperm function, egg quality and early embryo development. Most male studies in its summary table compared men with their own starting values, the two small placebo-controlled studies paired ubiquinol with other ingredients, and the only placebo-controlled trial of ubiquinol alone (2012) has since received an expression of concern from its journal.