Ubiquinone is the most common form of CoQ10 found in supplements. After ingestion, ubiquinone is converted into ubiquinol (the reduced form of CoQ10), which has the most antioxidant properties.[1][2] The effectiveness of supplementation with ubiquinol compared to ubiquinone is still unclear. Some studies suggest that ubiquinol may be more effective,[2] while others report no significant difference between the two.[3]
The bioavailability of CoQ10 depends not just on whether it’s taken in the oxidized or reduced form, but also on the supplement formulation. For absorption in the gastrointestinal tract, CoQ10 crystals obtained via synthesis (in a lab or via the yeast fermentation method) must be dissociated into individual CoQ10 molecules, and this dissociation should be maintained throughout the shelf life of the CoQ10 preparation to be effective. This crystal dispersion process appears to play an important role in increasing the bioavailability of CoQ10. Notably, most studies suggesting the superiority of ubiquinol supplementation did not compare it to ubiquinone-dispersed formulations, likely due to their unavailability at the time of the study.[4]