Flavonoids, Blood Pressure and Blood Vessel Function

University of East Anglia64 enrolled

Overview

The primary aim of this placebo-controlled study is to determine whether flavonoids beneficially affect markers of cardiovascular disease risk in healthy subjects at elevated cardiovascular risk. The underlying mechanisms of action of flavonoids will be assessed on blood biomarkers and we will assess the effects of the food matrix, and aspects of isoflavone metabolism.

The study population will be healthy males (aged 50-75 years) at elevated risk of cardiovascular (CV) disease. A target of 60 participants will be required to complete the study and a total of 70 subjects will be targeted (n=70 subjects \* \~85% anticipated completion rate = 60 subjects to complete the study). This placebo-controlled study will test the relative efficacy of 4 different flavonoid sub-classes ((i) flavan-3-ol, (ii) anthocyanin, (iii) flavanone and (iv) isoflavone). Accordingly, subjects will be randomised to one of the four flavonoid study groups ((i) to (iv) outlined above), and then will consume each of the following treatments in random order: 1. dietary flavonoid + placebo supplement 2. placebo food + commercially available/produced flavonoid supplement 3. placebo food + placebo supplement Additionally, an isoflavone metabolite will be fed to establish potential vascular effects. Each sub-class will be assessed separately and a 1 week wash-out period between treatments will be observed. At each assessment visit, vascular function will be assessed pre- and post-intervention, with subsequent assessments made to coincide with anticipated peak plasma concentrations. Dietary intake will be monitored during the study and participants will be required to adhere to a range of dietary and lifestyle restrictions within 3 days of each assessment to reduce potential confounding of the data assessment of interest. A standard battery of vascular function tests will be performed on all intervention groups, with each assessment visit performed in an identical manner.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

TRIPLE

Enrollment

Conditions

Cardiovascular Disease Risk Reduction

Interventions

Flavanone - supplementDIETARY_SUPPLEMENT

acute single optimal dose

Flavanone - foodOTHER

acute single dose

Flavanone - placeboOTHER

acute single dose (flavanone free)

Eligibility

Sex: MALEMin age: 50 YearsMax age: 75 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Males * 50 to 75 years old * At elevated risk of CV disease * Screening blood pressure of \< 160/90mmHg (at rest) * Successful biochemical, haematological and urinalysis assessment at screening (as judged by clinical advisor) Exclusion Criteria: * Current smokers, or ex-smokers ceasing \< 3 months ago * Subjects with existing or significant past medical history of vascular disease or medical conditions likely to affect the study measures (as judged by clinical advisor) * Those with known allergies to the intervention treatments * Those unprepared to adhere to dietary restrictions during the trial * Parallel participation in another research project which involves concurrent dietary intervention and/or sampling of biological fluids/material * Having vaccinations (excluding the flu vaccination) or antibiotics within 3 months of start of trial, and those with vaccinations scheduled for during the trial * Taking flavonoid containing food / dietary supplements likely to affect the study results * Prescribed lipid lowering, hypertension, vasodilators (e.g. Viagra) or antibiotic medication * Unsatisfactory biochemical, haematological or urinary assessment at screening, indicating abnormal; renal or liver function, full blood profile, impaired glucose handling, deranged lipids or measurements considered to be counter indicative of the study by the clinical advisor

Locations (1)

Department of Nutrition, Norwich Medical School

Norwich, Norfolk, United Kingdom

Outcomes

Primary Outcomes

Change from baseline in blood vessel control (pressure and endothelial function) at time points coinciding with postprandial [anticipated] peak plasma flavonoid concentration.

Assessment of vascular function

Time frame: acute postprandial; up to 24 hours, dependent on flavonoid sub-classification studied

Secondary Outcomes

Differences in effects of flavonoids introduced by food matrix

Time frame: acute postprandial; up to 24 hours dependent on flavonoid sub-classification studied

Data from ClinicalTrials.gov

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