The Effect of Olive Leaf Extract on Blood Pressure in Overweight Prehypertensives

Effect of Chronic Polyphenol-rich Olive Leaf Extract Intake on Cardiovascular Risk Markers

Cardiovascular disease (CVD) is the leading cause of death in New Zealand (40% of all deaths). 37% of New Zealanders suffer from high blood pressure (World Health Organisation 2008 figures), a well established modifiable risk factor for CVD. Above 115/75 mmHg, CVD risk doubles for each increment of 20/10 mmHg that blood pressure is raised. An increase in BMI and waist circumference has been associated with an increase in blood pressure. The leaves of the olive plant are rich in plant compounds known as polyphenols. This particular group of polyphenols are known secoiridoids, which are also present in olive oil and olives though at lower concentrations, are only found in this family of plants. Diets high in polyphenols have been found to reduce the risk of chronic diseases. Studies have shown that consumption of phenolic-rich olive leaf extract (OLE) can significantly reduce blood pressure in individuals suffering from high blood pressure (hypertension), with the magnitude of effect being comparable to a commonly used antihypertensive drug. In such trials OLE also resulted in an improved blood lipid (a reduction in total and LDL cholesterol and triacylglycerides) which also reduces CVD risk. One study testing the effect of OLE on individuals with mild or prehypertension (i.e. those with systolic blood pressure in the range 121-139 mmHg and diastolic blood pressure in the range 81-89 mmHg but not taking antihypertensive medication) also found these same improvements. OLE has been indicated to have the potential to improve other cardiovascular risk markers such as vascular function, inflammation, platelet aggregation, oxidation of LDL and glucose tolerance however much of this evidence is derived from animal, in vitro and ex vivo studies and so well designed and controlled human studies are required to verify that these findings are applicable to humans. Therefore OLE supplementation may be a useful dietary strategy for reducing CVD risk in a cohort of overweight prehypertensive individuals.

The aim of the study is to determine the effect of OLE intake on blood pressure and other CVD risk markers in overweight subjects with mild hypertension and to link any study outcomes with the presence of OLE phenolics in urine

Study Overview

• Status: Completed
• Conditions: Hypertension
• Intervention / Treatment: Dietary supplement: Olive leaf extract liquid

• Study Type: Interventional
• Enrollment (Actual): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• New Zealand
  • Auckland
    • Albany, North Shore, Auckland, New Zealand, 0745
      • Institute of Food, Nutrition and Human Health, Massey University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 16 years to 63 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Male

Description

Inclusion Criteria:

Men 18-65 years; Non-smokers; Prepared to consume olive leaf extract liquid Systolic blood pressure 121-139 mmHg and diastolic blood pressure 81-89 mmHg Body mass index (BMI) between 25-30 kg/m2 or waist >102 cm

Exclusion Criteria:

Smokers Using blood pressure, lipid lowering, thyroid disorder, blood clotting medication Using supplements or functional foods that will affect lipid concentrations (e.g. sterol enriched spreads) Chronic disease e.g. CHD, diabetes, cancer, digestive disorders Individuals who are unwilling to refrain from consuming olive containing products for the duration of the study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Olive leaf extract liquid; 20ml of polyphenol-rich olive leaf extract liquid to be consumed daily for 6 weeks	Dietary supplement: Olive leaf extract liquid; Commercially available polyphenol-rich olive leaf extract liquid
Placebo Comparator: Placebo liquid; 20ml of polyphenol-free placebo liquid (containing water, glycerin, flavours, colours and aromas) to be consumed daily for 6 weeks

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Blood pressure measured via 24 hour ambulatory blood pressure monitors	6 weeks

Secondary Outcome Measures

Outcome Measure	Time Frame
Vascular function assessed by pulse wave velocity (PWV)	6 weeks
Lipid profile measured via serum assay	6 weeks
Inflammatory cytokines measured via plasma assay	6 weeks
Fructosamine measured via plasma assay	6 weeks
Glucose measured via plasma assay	6 weeks
Nitric oxide measured via plasma assay	6 weeks
Insulin measured via plasma assay	6 weeks
Haemostatic factors (D-dimer, PAI-1 ag, von Willebrand factor, prothrombin F1+2, factor VIII) measured via plasma assay	6 weeks
Oxidised LDL measured via plasma assay	6 weeks
Obesity markers (adiponectin, CCL-2, complement factor D, CRP, IL-6, IL-10, leptin, resistin, serpin E1 and TNF-a) measured via plasma assay	6 weeks

Collaborators and Investigators

• Sponsor: University of Reading
• Collaborators: Massey University
• Investigators: Principal Investigator: Welma Stonehouse, PhD, Massey University

Study record dates

Study Major Dates

• Study Start: February 1, 2013
• Primary Completion (Actual): October 1, 2013
• Study Completion (Actual): October 1, 2013

Study Registration Dates

• First Submitted: February 20, 2013
• First Submitted That Met QC Criteria: February 20, 2013
• First Posted (Estimate): February 21, 2013

Study Record Updates

• Last Update Posted (Estimate): October 11, 2013
• Last Update Submitted That Met QC Criteria: October 10, 2013
• Last Verified: October 1, 2013

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases; Hypertension
• Other Study ID Numbers: OLE chronic study