Nutritional value of olive oil
Olive oil has major and minor components. The former are the fatty acids, of which the monounsaturated fatty acid (MUFA), the oleic acid, represents from 55% to 83% of the total fatty acids. The minor components of olive oil constitute from 1% to 2% of the total content of an olive oil and are classified as: 1) the unsaponifiable fraction, which can be extracted with solvents after the saponification of the oil and contains squalene and other triterpenes, sterols, tocopherol, and pigments, and 2) the soluble fraction that includes the phenolic compounds, the complex forms called polyphenols. Phenolic compounds are present as simple phenols or conjugated forms. Tyrosol (Tyr), hydroxy-tyrosol (OHTyr), and their derivatives make up around 90% of the total phenolic content of a virgin olive oil. Phenolic compounds from olive oil are the most studied and best-known components in terms of their benefits for health. The content of the minor components of an olive oil varies, depending on the cultivar, climate, ripeness of the olives at harvesting, and the processing system employed to produce the olive oil. Olive oils are obtained from the fruit of the olive tree solely by mechanical or other physical means, under conditions that do not lead to oil alterations.
[Tuck KL, Hayball PJ. Major phenolic compounds in olive oil: metabolism and health effects. J. Nutr. Biochem. (2002) Nov., 13(11):636-644. doi: 10.1016/s0955-2863(02)00229-2. PMID: 12550060]
Structures of the major phenolic compounds identified in olives and olive oil
[Tuck KL, Hayball PJ. Major phenolic compounds in olive oil: metabolism and health effects. J Nutr Biochem. (2002) Nov., 13(11):636-644. doi: 10.1016/s0955-2863(02)00229-2. PMID: 12550060]
[María-Isabel Covas, Rafael de la Torre, Montserrat Fitó, (2014). Scientific evidence of the benefits of virgin olive oil for human health. Medicina Balear, 29(2), 39-46]
Extra-VOOs are VOOs with a free acidity, expressed as g of oleic acid/100 g of olive oil, less than 0.8 g. One of the prerequisites for assessing the physiological significance of olive oil phenolic compounds is the ability to determine their bioavailability in human beings. Tyr and OHTyr are absorbed by humans from olive oil in a dose dependent manner with the phenolic content of the olive oil administered both after a single dose or after sustained olive oil consumption. This implies an accumulation in the body even from moderate doses of olive oil (25 mL/d) which are lower than the traditional daily dietary intake in Mediterranean countries (30-50 g/day). The bioavailability of OHTyr, however, has been shown to change largely depending on the matrix in which the phenolic compounds are administered, the most effective matrix being the olive oil. Around 98% of Tyr and OHTyr are present in plasma and urine in conjugated forms, glucuronoconjugates or sulfates. This fact indicates the existence of an extensive first-pass intestinal/hepatic metabolism of the ingested primary forms.
[Boronat, Anna & Pujadas, Mitona & Rodríguez-Morató, Jose & Pérez-Mañá, Clara & Pastor, Antoni & de la Torre, Rafael. (2016). DETERMINATION OF FREE AND CONJUGATED HYDROXYTYROSOL IN HUMAN PLASMA FOLLOWING OLIVE OIL ADMINISTRATION. 10.18143/JISANH_v3i4_1279]