Efectos antioxidantes del aceite de oliva y de sus compuestos fenólicos
Since olive oil is acquiring an increasing importance in the health benefit of the Mediterranean diet, and with the objective of making nutritional recommendations to the population in the future, several studies about the antioxidant effects of olive oil were undertaken. These investigations included in vitro and human studies.
The protective action of the olive oil phenolic compounds against the LDL oxidation in vitro was studied. The results showed that all the olive oil tested (with similar contents in fatty acid and vitamin E, but with differences in the phenolic compound content) increased the LDL resistance to oxidation versus the LDL control. Furthermore, differences in the nature of the olive oil phenolic compound (with the same phenolics concentration) influenced the resistance of LDL to oxidation.
When specifically studied the effect of the olive oil phenolic extracts on the protection of the LDL particle to oxidation, we observed an increase of the resistance of LDL to oxidation directly related with the olive oil phenolics compounds concentration incubated with the lipoproteins. On the other hand, an increase was observed specifically on the LDL resistance to oxidation related directly with the olive oil phenolic compounds concentration incubated with plasma.
A methodology to detect and quantify phenolic compounds linked to LDL of non supplemented volunteers was designed, in order to investigate if phenolics taken with diet could link to the LDL particles in vivo. To study if olive oil phenolic compounds could link to the LDL, we incubated olive oil phenolic compounds with human plasma and the content of olive oil phenolics were determined. The results showed that tyrosol can bind to LDL lipoprotein.
Once antioxidant effects of olive oil phenolic compounds were tested in vitro and the incorporation of phenolics to LDL in vivo, several studies in humans were designed. Three studies with healthy volunteers were performed in order to investigate the postprandial effects after the olive oil consumption, and the short- and long-term effects of a regular and moderate olive oil ingestion. An oxidative postprandial stress after the ingestion of 50 mL of virgin olive oil was observed, reflected in a lipoperoxides increment in plasma and in a decrease of the antioxidant enzymes activity in plasma (glutation peroxidase and glutation reductase activity). Nevertheless no changes in the LDL resistance to oxidation were appreciated in the postprandial phase. The short-term study about the effects on the oxidative stress of an ingestion of virgin olive oil showed an increment in the LDL resistance to oxidation, in the glutation reductase activity and in the oleic acid concentration in plasma, after consuming virgin olive oil (25 mL/day) during one week.
Finally, a randomized clinical trial was performed with the aim of studying the long-term effects (3 weeks) of the ingestion of three olive oils with different phenolic compounds content. A decrease of the oxidized LDL levels in plasma and the LDL resistance to oxidation were observed directly related with the phenolic compounds present in the olive oil administered.
Advisor:Covas Planell, Maria Isabel
School:Universitat Autónoma de Barcelona
Source Type:Master's Thesis
Keywords:417 departament de medicina
Date of Publication:06/11/2003