CoQ10, the cell's electron carrier: does taking it raise blood levels? In older men, ubiquinol did

In a two-week trial of 10 older men, 200 mg a day of ubiquinol, the reduced form of CoQ10, raised the CoQ10 in their blood from 1.3 to 3.4 micromoles per liter (µmol/L). A 2023 systematic review of 16 studies in athletes linked CoQ10 to better anaerobic performance and lower oxidative-stress and fatigue markers. CoQ10 is an electron carrier in your cells’ energy chain, and its structure has not changed from bacteria to vertebrates like us. Here is how scientists came to know it, and what the human trials have measured.

How it was found

CoQ10 (also called ubiquinone) was first known for its job inside the mitochondrion, the cell’s power station: carrying electrons and protons through the electron transport chain (Garrido-Maraver 2014). That chain is how cells make ATP, the molecule they run on for energy (Zhang 2018).

Then the picture widened. Later studies found CoQ10 in other cell membranes and in blood plasma, the watery part of your blood (Garrido-Maraver 2014). A 2024 review places it in most, and maybe all, biological membranes, and notes that every animal cell makes its own (Wang 2024). A molecule first known for one job in one part of the cell turned out to be made by every cell and carried in the blood.

The surprise deepened with its history. Its structure, and therefore its properties, have not changed from bacteria to vertebrates (Wang 2024). It is so hydrophobic (water-repelling) that it lives in membranes, and that makes building it in the cell particularly complex (Wang 2024). Newer supplement formulations have been developed to increase its absorption (Garrido-Maraver 2014), and scientists have tested whether taking it changes the levels in the blood.

What the human trials later showed

When scientists gave people the reduced form, the level in their blood rose. In a 2018 randomized, double-blind crossover trial, 10 older men took 200 mg a day of ubiquinol (reduced CoQ10) and of ubiquinone (oxidized CoQ10), two weeks of each with a two-week break between. After two weeks of ubiquinol, their blood total CoQ10 rose from 1.3 to 3.4 µmol/L (Zhang 2018). Ubiquinone made no significant change, and neither form changed the oxidative-stress markers the trial measured. That is a concrete result: a set daily dose, a named form and a rise you can see on a blood test.

A wider picture comes from a 2023 systematic review of 16 studies in athletes aged 17 and older, across different sports, who took 30 to 300 mg of CoQ10 by mouth. After supplementing, the studies found higher anaerobic performance, higher antioxidant activity in the blood, and lower oxidative-stress markers and fatigue indicators such as creatine kinase (Fernandes 2023). Together, the two show the reduced form reaching the blood and, in people who train, CoQ10 moving performance and fatigue markers in the helpful direction.

Where it stands now

These two human studies show two things: the reduced form raised blood CoQ10 in older men within two weeks (Zhang 2018), and in athletes, CoQ10 was linked to better anaerobic performance and lower fatigue indicators (Fernandes 2023). The 2024 review also notes that CoQ10 runs low alongside aging (Wang 2024).

The same review says that whether taking CoQ10 by mouth brings any health benefit is not yet well established (Wang 2024).

Next step

To see the doses and durations the human trials used, read our guide: Does CoQ10 get into your blood?