The effect of polyphenols in olive oil on heart disease risk factors: a randomized trial.
BACKGROUND
Virgin olive oils are richer in phenolic content than refined olive oil. Small, randomized, crossover, controlled trials on the antioxidant effect of phenolic compounds from real-life daily doses of olive oil in humans have yielded conflicting results. Little information is available on the effect of the phenolic compounds of olive oil on plasma lipid levels. No international study with a large sample size has been done.


OBJECTIVE
To evaluate whether the phenolic content of olive oil further benefits plasma lipid levels and lipid oxidative damage compared with monounsaturated acid content.


METHODS
Randomized, crossover, controlled trial.


METHODS
6 research centers from 5 European countries.


METHODS
200 healthy male volunteers.


METHODS
Glucose levels, plasma lipid levels, oxidative damage to lipid levels, and endogenous and exogenous antioxidants at baseline and before and after each intervention.


METHODS
In a crossover study, participants were randomly assigned to 3 sequences of daily administration of 25 mL of 3 olive oils. Olive oils had low (2.7 mg/kg of olive oil), medium (164 mg/kg), or high (366 mg/kg) phenolic content but were otherwise similar. Intervention periods were 3 weeks preceded by 2-week washout periods.


RESULTS
A linear increase in high-density lipoprotein (HDL) cholesterol levels was observed for low-, medium-, and high-polyphenol olive oil: mean change, 0.025 mmol/L (95% CI, 0.003 to 0.05 mmol/L), 0.032 mmol/L (CI, 0.005 to 0.05 mmol/L), and 0.045 mmol/L (CI, 0.02 to 0.06 mmol/L), respectively. Total cholesterol-HDL cholesterol ratio decreased linearly with the phenolic content of the olive oil. Triglyceride levels decreased by an average of 0.05 mmol/L for all olive oils. Oxidative stress markers decreased linearly with increasing phenolic content. Mean changes for oxidized low-density lipoprotein levels were 1.21 U/L (CI, -0.8 to 3.6 U/L), -1.48 U/L (-3.6 to 0.6 U/L), and -3.21 U/L (-5.1 to -0.8 U/L) for the low-, medium-, and high-polyphenol olive oil, respectively.


CONCLUSIONS
The olive oil may have interacted with other dietary components, participants' dietary intake was self-reported, and the intervention periods were short.


CONCLUSIONS
Olive oil is more than a monounsaturated fat. Its phenolic content can also provide benefits for plasma lipid levels and oxidative damage. International Standard Randomised Controlled Trial number: ISRCTN09220811.
Covas
María-Isabel
MI
Municipal Institute for Medical Research, Barcelona, Spain. mcovas@imim.es
Nyyssönen
Kristiina
K
Poulsen
Henrik E
HE
Kaikkonen
Jari
J
Zunft
Hans-Joachim F
HJ
Kiesewetter
Holger
H
Gaddi
Antonio
A
de la Torre
Rafael
R
Mursu
Jaakko
J
Bäumler
Hans
H
Nascetti
Simona
S
Salonen
Jukka T
JT
Fitó
Montserrat
M
Virtanen
Jyrki
J
Marrugat
Jaume
J
D000328:Adult; D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology*; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood / Q000187:drug effects*; D018592:Cross-Over Studies; D004042:Dietary Fats, Unsaturated / Q000032:analysis*; D005419:Flavonoids / Q000494:pharmacology*; D006331:Heart Diseases / Q000097:blood* / Q000517:prevention & control; D006801:Humans; D008297:Male; D008875:Middle Aged; D000069463:Olive Oil; D010349:Patient Compliance; D010352:Patient Dropouts; D010636:Phenols / Q000494:pharmacology*; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives / Q000652:urine; D010938:Plant Oils / Q000737:chemistry*; D059808:Polyphenols; D012307:Risk Factors; D014280:Triglycerides / Q000097:blood
D000975:Antioxidants; D008076:Cholesterol, HDL; D004042:Dietary Fats, Unsaturated; D005419:Flavonoids; D000069463:Olive Oil; D010636:Phenols; D010938:Plant Oils; D059808:Polyphenols; D014280:Triglycerides; C005975:3,4-dihydroxyphenylethanol; C011867:4-hydroxyphenylethanol; D002784:Cholesterol; D010626:Phenylethyl Alcohol