Absorption, Distribution, Metabolism, and Excretion of the Main Olive Tree Phenols and Polyphenols: A Literature Review

The effects of olive tree (poly)phenols (OPs) are largely dependent upon their bioavailability and metabolization by humans. Absorption, distribution, metabolism, and excretion (ADME) are fundamental for the nutritional efficacy and toxicological impact of foods containing OPs. This review includes studies on the administration of hydroxytyrosol (HT), oleuropein (Ole), or other OPs and foods, products, or mixtures that contain them. Briefly, data from in vivo studies indicate that OPs are absorbable by intestinal cells. Both absorption and bioavailability depend upon each compound and/or the matrix in which it is contained. OPs metabolism begins in enterocytes and can also continue in the liver. Metabolic phase I mainly consists of the hydrolysis of Ole, which results in an increase in the HT content. Phase II metabolic reactions involve the conjugation of (poly)phenols mainly with glucuronide and sulfate groups. This review offers a complete perspective of the ADME processes of OPs, which could support the future nutritional and/or toxicological studies in this area.