title: Secoiridoids delivered as olive leaf extract induce acute improvements in human vascular function and reduction of an inflammatory cytokine: a randomised, double-blind, placebo-controlled, cross-over trial.
abstract: The leaves of the olive plant (Olea europaea) are rich in polyphenols, of which oleuropein and hydroxytyrosol (HT) are most characteristic. Such polyphenols have been demonstrated to favourably modify a variety of cardiovascular risk factors. The aim of the present intervention was to investigate the influence of olive leaf extract (OLE) on vascular function and inflammation in a postprandial setting and to link physiological outcomes with absorbed phenolics. A randomised, double-blind, placebo-controlled, cross-over, acute intervention trial was conducted with eighteen healthy volunteers (nine male, nine female), who consumed either OLE (51 mg oleuropein; 10 mg HT), or a matched control (separated by a 4-week wash out) on a single occasion. Vascular function was measured by digital volume pulse (DVP), while blood collected at baseline, 1, 3 and 6 h was cultured for 24 h in the presence of lipopolysaccharide in order to investigate effects on cytokine production. Urine was analysed for phenolic metabolites by HPLC. DVP-stiffness index and ex vivo IL-8 production were significantly reduced (P< 0.05) after consumption of OLE compared to the control. These effects were accompanied by the excretion of several phenolic metabolites, namely HT and oleuropein derivatives, which peaked in urine after 8-24 h. The present study provides the first evidence that OLE positively modulates vascular function and IL-8 production in vivo, adding to growing evidence that olive phenolics could be beneficial for health.
authors.affiliation: Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences, University of Reading,BerkshireRG6 6AP,UK.
authors.forename: Stacey
authors.initials: S
authors.lastname: Lockyer
authors.affiliation: Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences, University of Reading,BerkshireRG6 6AP,UK.
authors.forename: Giulia
authors.initials: G
authors.lastname: Corona
authors.affiliation: Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences, University of Reading,BerkshireRG6 6AP,UK.
authors.forename: Parveen
authors.initials: P
authors.lastname: Yaqoob
authors.affiliation: Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences, University of Reading,BerkshireRG6 6AP,UK.
authors.forename: Jeremy P E
authors.initials: JP
authors.lastname: Spencer
authors.affiliation: Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences, University of Reading,BerkshireRG6 6AP,UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Rowland
mesh_terms: D001682:Biological Availability; D001808:Blood Vessels / Q000187:drug effects / Q000502:physiology*; D018592:Cross-Over Studies; D016207:Cytokines / Q000097:blood*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000517:prevention & control*; D057888:Iridoid Glucosides; D039823:Iridoids / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008297:Male; D031658:Olea; D010636:Phenols / Q000493:pharmacokinetics / Q000652:urine; D010919:Placebos; D010936:Plant Extracts / Q000008:administration & dosage / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry*; D011674:Pulse; D059289:Vascular Stiffness
chemical_list: D016207:Cytokines; D057888:Iridoid Glucosides; D039823:Iridoids; D010636:Phenols; D010919:Placebos; D010936:Plant Extracts; C002769:oleuropein
keywords: CVD; Dietary polyphenols bioavailability; Inflammatory cytokines; Olive leaf extract; Vascular function