title: Extra virgin olive oil phenols and markers of oxidation in Greek smokers: a randomized cross-over study.
abstract: OBJECTIVE
  To examine the effect of a low phenol olive oil and high phenol olive oil on markers of oxidation and plasma susceptibility to oxidation in normolipaemic smokers.
  
  
  METHODS
  Randomized single-blind cross-over trial with two intervention periods.
  
  
  METHODS
  The Medical School and University Hospital of the University of Crete, Heraklion, Crete, Greece.
  
  
  METHODS
  Twenty-five healthy males and females completed the study.
  
  
  METHODS
  Each intervention was of three weeks duration and intervention periods were separated by a two week washout. Seventy grams of extra virgin olive oil was supplied to each subject per day in the intervention periods. The olive oils supplied differed in their phenol content by 18.6 mg/day. Two fasting venous blood samples were taken at the end of each intervention period.
  
  
  RESULTS
  The markers of antioxidant capacity measured in fasting plasma samples (total plasma resistance to oxidation, concentrations of protein carbonyl as a marker of protein oxidation, malondialdehyde and lipid hydroperoxides as markers of lipid oxidation and the ferric reducing ability of plasma) did not differ significantly between the low and high phenol olive oil diets.
  
  
  CONCLUSIONS
  No effect of olive oil phenols on markers of oxidation in smokers was detected. It may be that the natural concentrations of phenols in olive oil are too low to produce an effect in the post-absorptive phase. Possible reasons for period effects and interactions between diet and administration period need attention to aid further cross-over trials of this kind.
  
  
  BACKGROUND
  Unilever Research Vlaardingen, The Netherlands.
authors.affiliation: Preventive Medicine and Nutrition Clinic, Department of Social Medicine, School of Medicine, University of Crete, Heraklion, Crete, Greece.
authors.forename: J
authors.initials: J
authors.lastname: Moschandreas
authors.forename: M N
authors.initials: MN
authors.lastname: Vissers
authors.forename: S
authors.initials: S
authors.lastname: Wiseman
authors.forename: K P
authors.initials: KP
authors.lastname: van Putte
authors.forename: A
authors.initials: A
authors.lastname: Kafatos
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005215:Fasting; D005260:Female; D006115:Greece; D006801:Humans; D015227:Lipid Peroxidation; D008297:Male; D008315:Malondialdehyde / Q000097:blood; D000069463:Olive Oil; D010084:Oxidation-Reduction; D010636:Phenols / Q000494:pharmacology*; D010938:Plant Oils / Q000737:chemistry* / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D016037:Single-Blind Method; D012907:Smoking
chemical_list: D015415:Biomarkers; D000069463:Olive Oil; D010636:Phenols; D010938:Plant Oils; D011506:Proteins; D008315:Malondialdehyde