Clinical trial NCT01796561: The Effect of Olive Leaf Extract on Blood Pressure in Overweight Prehypertensives
Official title: Effect of Chronic Polyphenol-rich Olive Leaf Extract Intake on Cardiovascular Risk Markers
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Hypertension
Lead sponsor: University of Reading
Sponsor class: OTHER
Collaborators: name: Massey University
First posted: 2013-02-21
Enrollment: 60
Sex: MALE
Minimum age (years): 18
Maximum age (years): 65
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: PREVENTION

Brief summary: 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


Eligibility criteria: 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

Primary outcomes:
measure: Blood pressure measured via 24 hour ambulatory blood pressure monitors
timeFrame: 6 weeks
Secondary outcomes:
measure: Vascular function assessed by pulse wave velocity (PWV)
timeFrame: 6 weeks
measure: Lipid profile measured via serum assay
timeFrame: 6 weeks
measure: Inflammatory cytokines measured via plasma assay
timeFrame: 6 weeks
measure: Fructosamine measured via plasma assay
timeFrame: 6 weeks
measure: Glucose measured via plasma assay
timeFrame: 6 weeks
measure: Nitric oxide measured via plasma assay
timeFrame: 6 weeks
measure: Insulin measured via plasma assay
timeFrame: 6 weeks
measure: Haemostatic factors (D-dimer, PAI-1 ag, von Willebrand factor, prothrombin F1+2, factor VIII) measured via plasma assay
timeFrame: 6 weeks
measure: Oxidised LDL measured via plasma assay
timeFrame: 6 weeks
measure: Obesity markers (adiponectin, CCL-2, complement factor D, CRP, IL-6, IL-10, leptin, resistin, serpin E1 and TNF-a) measured via plasma assay
timeFrame: 6 weeks
Other outcomes:
Locations:
city: Albany, North Shore
country: New Zealand
facility: Institute of Food, Nutrition and Human Health, Massey University
state: Auckland
Study officials:
affiliation: Massey University
name: Welma Stonehouse, PhD
role: PRINCIPAL_INVESTIGATOR
References: