title: The effect of polyphenols in olive oil on heart disease risk factors: a randomized trial.
abstract: 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.
authors.affiliation: Municipal Institute for Medical Research, Barcelona, Spain. mcovas@imim.es
authors.forename: María-Isabel
authors.initials: MI
authors.lastname: Covas
authors.forename: Kristiina
authors.initials: K
authors.lastname: Nyyssönen
authors.forename: Henrik E
authors.initials: HE
authors.lastname: Poulsen
authors.forename: Jari
authors.initials: J
authors.lastname: Kaikkonen
authors.forename: Hans-Joachim F
authors.initials: HJ
authors.lastname: Zunft
authors.forename: Holger
authors.initials: H
authors.lastname: Kiesewetter
authors.forename: Antonio
authors.initials: A
authors.lastname: Gaddi
authors.forename: Rafael
authors.initials: R
authors.lastname: de la Torre
authors.forename: Jaakko
authors.initials: J
authors.lastname: Mursu
authors.forename: Hans
authors.initials: H
authors.lastname: Bäumler
authors.forename: Simona
authors.initials: S
authors.lastname: Nascetti
authors.forename: Jukka T
authors.initials: JT
authors.lastname: Salonen
authors.forename: Montserrat
authors.initials: M
authors.lastname: Fitó
authors.forename: Jyrki
authors.initials: J
authors.lastname: Virtanen
authors.forename: Jaume
authors.initials: J
authors.lastname: Marrugat
mesh_terms: 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
chemical_list: 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