RESUMEN
A lack of understanding of the processes determining the absorption and subsequent metabolism of coenzyme Q10 (CoQ10) has resulted in some manufacturers' making incorrect claims regarding the bioavailability of their CoQ10 supplements, with potential consequences for the use of such products in clinical trials. The purpose of the present review article is, therefore, to describe the various stages of exogenous CoQ10 metabolism, from its first ingestion, stomach transit, absorption from the small intestine into the lymphatic system, transport in blood, and access into cells. In particular, the importance of CoQ10 crystal dispersion in the initial formulation is emphasised, the absence of which reduces bioavailability by 75%. In addition, evidence comparing the relative bioavailability and efficacy of ubiquinone and ubiquinol forms of CoQ10 has been reviewed.