Factors influencing the bioavailability of antioxidants in foods : a critical appraisal

An important aspect when studying the role of antioxidants in human health is the evaluation of their bioavailability from foods. This aspect is gaining increasing interest as food industries are continually involved in developing new products, defined as ‘‘functional’’ by virtue of the presence of specific antioxidants or phytochemicals. The bioavailability of these substances is, however, not always well known. Although, from a theoretical point of view, several definitions of bioavailability have been suggested, the most appropriate seems to be as that fraction of an ingested nutrient or compound that reaches the systemic circulation and the specific sites where it can exert its biological action. In this definition, three main steps are implicit: release from the carrier matrix, intestinal absorption and tissue uptake. These aspects are discussed in the paper.