How Ubiquinone (CoQ10) is Best Absorbed
CoQ10 absorption is significantly enhanced when taken as ubiquinol (the reduced form) rather than ubiquinone (the oxidized form), with ubiquinol achieving approximately 70% higher plasma levels at equivalent doses. 1
Optimal Formulation
Ubiquinol demonstrates superior bioavailability compared to ubiquinone, with plasma CoQ10 levels reaching 4.3 µg/mL versus 2.5 µg/mL after 4 weeks of 200 mg/day supplementation, and CoQ10/cholesterol ratios of 1.2 versus 0.7 µmol/mmol respectively. 1
Both forms are absorbed by the small intestine predominantly in their original form without significant interconversion during digestion, contrary to previous assumptions that ubiquinol would oxidize in the gastrointestinal tract. 2
In patients with severe heart failure and intestinal edema who failed to achieve therapeutic levels on ubiquinone (mean 1.6 µg/mL on 450 mg/day), switching to ubiquinol at 580 mg/day increased plasma levels to 6.5 µg/mL, demonstrating dramatically improved absorption in compromised states. 3
Critical Absorption Characteristics
CoQ10 has inherently poor intestinal absorption due to its hydrophobicity and large molecular weight, with peak plasma levels occurring 5-10 hours after ingestion due to slow absorption kinetics. 4, 5
The compound is transported in plasma by low-density lipoproteins (LDL), making plasma CoQ10 levels dependent on lipoprotein status. 4
Taking CoQ10 with fat-containing meals significantly enhances absorption given its lipid-soluble nature, though this is not explicitly stated in guidelines, it follows from its classification as a fat-soluble compound. 4
Dosing Considerations for Absorption
Absorption increases non-linearly with dose, meaning doubling the dose does not double plasma levels—after single doses, 150 mg achieved 1.88 µg/mL while 300 mg only reached 3.19 µg/mL. 6
For therapeutic purposes, doses of 50-1200 mg/day have been studied in adults, with up to 3000 mg/day being well-tolerated, though higher doses show diminishing returns on absorption. 4, 7
Steady-state plasma levels plateau by day 14 of supplementation, with trough concentrations of 2.61 µg/mL for 90 mg/day, 3.66 µg/mL for 150 mg/day, and 6.53 µg/mL for 300 mg/day. 6
Common Pitfalls
Patients with intestinal edema, malabsorption syndromes, or severe heart failure may have dramatically impaired absorption of ubiquinone and should be preferentially started on ubiquinol formulations. 3
No IV formulation exists, limiting options for patients unable to absorb oral supplements effectively. 4, 7
Measuring plasma CoQ10 levels should ideally be expressed as a ratio with total plasma cholesterol for clinical relevance, as CoQ10 is carried by lipoproteins. 4
Average dietary intake is only 3-6 mg/day from food sources (primarily meat, fish, nuts, and oils), far below supplementation doses needed for therapeutic effects. 7, 8