Dietary Supplement. Cardiovascular Health. Active Antioxidant Form of CoQ10 - 50 mg. Higher Bioavailability NOW® Ubiquinol CoQH-CF™ contains the reduced form of CoQ10 which has been shown in scientific studies to be a highly bioavailable and active antioxidant form of CoQ10. The addition of d-Limonene to this product naturally improves its solubility, which further enhances intestinal absorption, and thereby provides superior overall biological value. Coenzyme Q10 is present in almost all cells, where it is necessary for mitochondrial energy production. The body s highest concentrations of CoQ10 are found in the heart, where constant chemical energy availability.