Absorption and Metabolism of Olive Leaf Extract and Its Effect on Vascular Reactivity and Cytokine Concentrations


The purpose of this study is to determine how olive leaf is absorbed and metabolised and also whether it has any effect on the elasticity of blood vessels and the immune system.

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Crossover Assignment
    • Primary Purpose: Basic Science
    • Masking: Double (Participant, Investigator)
  • Study Primary Completion Date: October 2011

Detailed Description

The purpose of this study is to determine how olive leaf is absorbed and metabolised and also whether it has any effect on vascular function and cytokine concentrations.


  • Dietary Supplement: Olive leaf extract capsules
    • Four capsules taken at baseline each containing 4mg oleuropein

Arms, Groups and Cohorts

  • Placebo Comparator: Placebo capsule
    • Four placebo capsules containing safflower oil only
  • Active Comparator: Olive leaf extract capsule
    • Four olive leaf capsules. Each containing 4mg oleuropein plus safflower oil.

Clinical Trial Outcome Measures

Primary Measures

  • Absorption and metabolism
    • Time Frame: 0. 0.5, 1, 1.5, 2, 3, 4, 6, 8 hours post ingestion (blood) 0, 0-4, 4-8 and 8-24 hours post ingestion (urine)
    • Olive leaf polyphenol metabolites measured in blood and urine samples

Secondary Measures

  • Vascular function
    • Time Frame: 0, 2, 4, 6 hours post ingestion (LDI) 0, 0.5, 1, 1.5, 2, 3, 4, 6 and 8 hours post ingestion (DVP)
    • Vascular function was assessed via two methods: Laser Doppler Iontophoresis (LDI) and Digital Volume Pulse (DVP)
  • Cytokine concentration
    • Time Frame: 0, 1, 3 and 6 hours post ingestion
    • Concentrations of IL-8, IL-1beta, IL-6, IL-10 and TNF-alpha will be measured in whole blood stimulated with LPS.

Participating in This Clinical Trial

Inclusion Criteria

  • 19-40 years, non-smokers, able to swallow capsules, have a Body Mass Index (BMI) of 18.5-30, have a normal liver function and haematology and a max alcohol intake of <21 units/week

Exclusion Criteria

  • Those who suffer from any form of disease, including endocrine disease, liver disease, diabetes mellitus, myocardial infarction, blood clotting disorder, reproductive disorder, gastrointestinal disease or a chronic gastrointestinal disorder.
  • Individuals who are vegetarian, have dietary restrictions or on a weight reducing diet will not be recruited.
  • Subjects who have been taking antibiotics in previous 3 months before study will not be included in the study
  • Females who may be pregnant, or if of childbearing potential and are not using effective contraceptive precautions will be excluded.
  • Blood pressure > 150/90 mmHg
  • Haemoglobin < 125 g/l for male, < 110 g/l for female
  • Gamma GT (liver enzymes) > 80 IU/l
  • Cholesterol > 6.5 mmol/l
  • Had suffered a myocardial infarction or stroke in the previous 12 months
  • On any lipid-modifying medication
  • On any medication affecting blood clotting
  • Individuals taking vitamin and/or fish oil supplements

Gender Eligibility: All

Minimum Age: 19 Years

Maximum Age: 40 Years

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • University of Reading
  • Collaborator
    • Comvita UK
  • Provider of Information About this Clinical Study
    • Principal Investigator: Jeremy Paul Edward Spencer, Professor of Biochemistry – University of Reading
  • Overall Official(s)
    • Jeremy PE Spencer, PhD, Principal Investigator, University of Reading
    • Ian Rowland, PhD, Principal Investigator, University of Reading
    • Parveen Yaqoob, PhD, Principal Investigator, University of Reading

Clinical trials entries are delivered from the US National Institutes of Health and are not reviewed separately by this site. Please see the identifier information above for retrieving further details from the government database.

At TrialBulletin.com, we keep tabs on over 200,000 clinical trials in the US and abroad, using medical data supplied directly by the US National Institutes of Health. Please see the About and Contact page for details.