Effects of differing phenolic content in dietary olive oils on lipids and LDL oxidation--a randomized controlled trial.
BACKGROUND
Evidence from in vitro studies suggests that antioxidant olive oil phenolic compounds can prevent LDL oxidation. However, in vivo evidence in support of this hypothesis is sparse.


OBJECTIVE
to establish the antioxidant effect of olive oils with differences in their phenolic compounds content in humans


METHODS
A controlled, double blind, cross-over, randomized, clinical trial using three similar olive oils with increasing phenolic concentration (from 0 to 150 mg/Kg) was conducted in 30 healthy volunteers. Olive oils were administered over three periods of 3 weeks preceded by two-week washout periods.


RESULTS
Urinary tyrosol and hydroxytyrosol increased (p < 0.020), in vivo plasma oxidized LDL decreased (p = 0.006), and ex vivo resistance of LDL to oxidation increased (p = 0.012) with the phenolic content of the olive oil administered. After virgin olive oil administration, an increase (p = 0.029) was observed in HDL cholesterol levels.


CONCLUSIONS
Sustained consumption of virgin olive oil with the high phenolic content was more effective in protecting LDL from oxidation and in rising HDL cholesterol levels than that of other type of olive oils. Dose-dependent changes in oxidative stress markers, and phenolic compounds in urine, were observed with the phenolic content of the olive oil administered. Our results support the hypothesis that virgin olive oil consumption could provide benefits in the prevention of oxidative processes.
Marrugat
Jaume
J
Lipids and Cardiovascular Epidemiology, Research Unit, Institut Municipal d'Investigació Mèdica, Carrer Dr Aiguader 80, 08003 Barcelona, Spain.
Covas
María-Isabel
MI
Fitó
Montserrat
M
Schröder
Helmut
H
Miró-Casas
Elisabet
E
Gimeno
Eva
E
López-Sabater
M Carmen
MC
de la Torre
Rafael
R
Farré
Magí
M
D000975:Antioxidants / Q000378:metabolism*; D008076:Cholesterol, HDL / Q000097:blood; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D006801:Humans; D008077:Lipoproteins, LDL / Q000737:chemistry* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D000069463:Olive Oil; D010084:Oxidation-Reduction; D010636:Phenols / Q000494:pharmacology*; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives* / Q000652:urine; D010938:Plant Oils / Q000737:chemistry*
D000975:Antioxidants; D008076:Cholesterol, HDL; D008077:Lipoproteins, LDL; D000069463:Olive Oil; D010636:Phenols; D010938:Plant Oils; C005975:3,4-dihydroxyphenylethanol; C011867:4-hydroxyphenylethanol; D010626:Phenylethyl Alcohol