Antioxidant effect of Olive Oil. Bioavailability of olive oil phenolic compounds in humans
From our results we have been able to establish:
- The high antioxidant capacity of olive oils with a high phenolic compound content (virgin), and the influence of the type of phenolic compound present in the oils on antioxidant capacity (Med Clin, 2000; Lipids, 2000).
- The protective effect on the ex vivo LDL oxidation of the whole content of phenolic compounds present in the virgin olive oil (Lipids, 2000), and of phenolic compounds isolated from olive oil as tyrosol (Int Pharmacol Res, 2000). In human studies, we have reported the capacity of phenolic compounds from olive oil and its metabolites to bind human LDL in vivo (J Chromatogr A, 2006; Anal Chim Acta, 2007) as well as the protective effect of olive oil phenolic compounds over other phenolic compounds bound to human LDL (Biol Res, 2004) in a dose-dependent manner with the phenolic compounds content of the olive oil administered (Free Rad Biol Med, 2006; Br J Nutr, 2007).
We also characterized the bioavailability of tyrosol and hydroxytyrosol, major olive oil phenolics, in humans (Drugs Exp Clin Res, 2003; Clin Chem, 2003, Eur J Clin Nutr,2003) from rea-life doses of natural olive oils.
In postprandial studies, we established :
- The lack of oxidative stress froma 25 mL dose of any type of olive oil (Drugs Exp Clin Res, 2004)
- Oxidative stress resulting from doses of 40 mL and 50 mL of any type of olive oil, modulated by the phenolic compounds of the olive oil (Lipids, 2001; Free Rad Biol Med, 2006).
- The anti-thrombotic effect of olive oil with high phenolic compounds content (Am J Clin Nutr, 2007).
Within the frame of short-term effects (1 week), we have reported:
- An increase in the antioxidant content in LDL (Eur J Nutr, 2000) after virgin olive oil consumption.
- A dose-dependent decrease in LDL and DNA oxidation in vivo, and an increase in glutathione related enzymes, in a dose-dependent manner with the phenolic content of the olive oil administered (J Nutr, 2003).
In studies of sustained effects of olive oil consumption (3 weeks) in randomized, crossover, controlled studies with healthy volunteers (Eur J Nutr, 2004) and stable CHD patients (Atherosclerosis, 2005; Eur J Clin Nutr, 2007), with an established high degree of oxidative stress (Atherosclerosis, 2003), we described a dose-dependent decrease of the in vivo LDL oxidation, systolic blood pressure, and inflammatory markers, related to the phenolic content of the olive oil administered.
Results of the EUROLIVE Study published in Ann Int Med, 2006; Free Rad Biol Med, 2006; FASEB J, 2007; J Nutr, 2007 and J Am Coll Nutr, 2007, showed the capacity of olive oil to:
- Counteract DNA oxidation withouth changes in DNA adducts formation.
- Increase the reduced glutathione content in a similar way in all types of olive oil.
- Increase HDL cholesterol and decrease lipid oxidative damage, dose-dependent on the phenolic content of the olive oil administered.
- Increase oleic acid content in the non-Mediterranean participants in an inverse relationship with the degree of lipid oxidative damage and systolic blood pressure levels.
(See reviews in: Nutr Rev, 2006; Pharmacol Res, 2007; Mol Nutr Food Res, 2007; Ann Ist Super Sanita, 2007; Inflammopharmacology, 2008)