Commercial coenzyme Q10 (CoQ10, ubiquinone) formulations are often of poor intestinal absorption. The relative bioavailability of CoQ10 has been shown in National Institutes of Health-funded clinical trials to be increased by its delivery system. We investigated the bioavailability of a new CoQ10 formulation based on a new and patented technology, VESIsorb, with 3 other commercially available CoQ10 products, an oil-based formulation and 2 solubilizates. This new CoQ10 formulation (commercially branded CoQsource) is a lipid-based formulation that naturally self-assembles on contact with an aqueous phase into an association colloid delivery system (hereafter "colloidal-Q10"). Twenty healthy male and female subjects participated in a double-blind, comparative (parallel design), controlled, single-dose (120 mg) bioavailability study. Plasma concentration of CoQ10 was determined at baseline and at various intervals after administration over a 24-hour period. To compare bioavailability, maximum concentration (Cmax) and area under curve from 0 to 10 hours (AUC(0-10h)) were assessed. The kinetic profiles of all CoQ10 preparations revealed a 1-peak plasma concentration-time course. Highest Cmax values were seen after colloidal-Q10 administration. Colloidal-Q10 not only had the highest plasma concentration levels after 1 hour, but it continued to increase before reaching Cmax at about 4 hours. The plasma concentration of colloidal-Q10 remained well above the levels of the 3 other products throughout the 24-hour period. The relative bioavailability calculated using the AUC(0-10h) values was also the highest for colloidal-Q10; the AUC(0-10h) values were 30.6, 6.1, 4.9, and 10.7 microg/mL*h for colloidal-Q10, solubilizate 1, the oil-based formulation, and solubilizate 2, respectively. Differences in Cmax and AUC between colloidal-Q10 and the 3 other formulations were statistically significant. In summary, the data presented suggests that colloidal-Q10 improves the enteral absorption and the bioavailability of CoQ10 in humans.