Bioavailability of phenolic compounds from olive oil and oxidative/antioxidant status at postprandial state in healthy humans.

Abstract

Olive oil phenolic compounds are generally believed to have beneficial antioxidant effects, but little is known about characteristics of their postprandial bioavailability in natural olive oil at real-life doses. The aim of the present study was to determine the concentrations of olive oil phenolic compounds in urine collected over 24 h (24-h urine) after a bolus ingestion of 25 ml of olive oil with different phenolic content, and to demonstrate the effect of this real-life olive oil dose on postprandial levels of blood lipids and oxidative stress biomarkers, as well as to examine the beneficial effects of olive oil phenols. Oral fat loads of 25 ml olive oil with high, moderate, and low phenolic content were administered to 12 healthy male volunteers in a randomized, controlled, crossover trial. Tyrosol and hydroxytyrosol were absorbed in a dose-dependent manner according to the phenolic content of the olive oil administered. The administered dose of 25 ml, which is close to that used daily in Mediterranean countries, did not induce significant postprandial lipemia nor did it promote an increase of in vivo oxidation markers. With regard to plasma antioxidant enzymes, glutathione peroxidase activity decreased postprandially after low phenolic content olive oil ingestion; however this was not observed after intake of moderate and high phenolic content olive oils. The phenolic content of the olive oils administered may account for the protection of the endogenous antioxidant defenses at postprandial state after ingestion of moderate and high phenolic content olive oils.