Effect of a Polyphenol Rich Diet on Vascular and Platelet Function

Study Overview
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Brief Summary
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Previous work has shown that increasing fruit and vegetable intake in patients with high blood pressure improves cardiovascular function. Research indicates that this may be partly owing to compounds called polyphenols, which are found in abundance in fruits and vegetables and other foods such as wine, tea and dark chocolate. The investigators now wish to test if consuming fruits and vegetables (including berries which are very rich in polyphenols), as well as dark chocolate, has further benefits for cardiovascular function. A total of 110 subjects with high blood pressure will be recruited and asked to follow a low polyphenol diet (2 portions of fruit and vegetables daily and no berries or dark chocolate) for four weeks (a washout period). They will then be randomised to continue this diet or to consume 6 portions of fruits and vegetables (to include 1 portion berries) and 1 portion of dark chocolate daily for 8 weeks. The fruit, vegetables and dark chocolate will be provided free of charge and delivered to the homes of the participants who are randomised to the high fruit and vegetable arm of the study. Assessment of microvascular and platelet function will be undertaken before and after consuming this diet. Improvements in these tests of cardiovascular function have previously been linked to reduced risks of heart disease in people with high blood pressure. This study will provide evidence as to whether or not a polyphenol rich diet can reduce the risk of developing heart disease.

Official Title
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Effect of a Polyphenol Rich Diet on Vascular and Platelet Function- a Randomised Control Trial

Conditions
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Hypertension

Intervention / Treatment
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* Other: Two portions of fruit and vegetables per day (excluding berries and dark chocolate)
* Other: Six portions of fruit and vegetables per day (one of which must be berries) and 50g dark chocolate.


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 40-65 years old Systolic blood pressure 140-179 mmHg or diastolic blood pressure 90-109 mmHg Exclusion Criteria: diabetes mellitus an acute coronary syndrome or transient ischaemic attack within the past 3 months special dietary requirements, food sensitivities or vegetarian/vegan diet by choice oral anticoagulation therapy body mass index greater than 35kg/m2 excessive alcohol consumption (defined as > 28 units/week in men and 21 units/week in women) fasting triglyceride concentration > 4 mmol/l pregnancy/lactation taking antioxidant supplements medical conditions or dietary restrictions that would substantially limit ability to complete the study requirements

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Low- polyphenol diet<br> | Other: Two portions of fruit and vegetables per day (excluding berries and dark chocolate)<br>* Two portions of fruit and vegetables per day (excluding berries and dark chocolate)<br>|
| Active Comparator: High-polyphenol diet<br> | Other: Six portions of fruit and vegetables per day (one of which must be berries) and 50g dark chocolate.<br>* Six portions of fruit and vegetables per day (one of which must be berries) and 50g dark chocolate.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Vascular function | Pharmacological provocation of endothelium-dependent vasomotion. | Measured at weeks 4 and 12 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Platelet function, biomarkers of cardiovascular risk and heart rate variability |  | Measured at weeks 0, 4 and 12 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Hypertension, Microvascular function