Clinical trial NCT01292954: Effect of Blueberries on Vascular Function in Healthy Men
Official title: Effects of Blueberries on Vascular Function and Blood Pressure in Healthy Men
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Healthy
Keywords: blueberries
vascular function
FMD
Blood pressure
Laser Doppler
pharmacokinetics
absorption
metabolism
polyphenols
flavonoids
Lead sponsor: University of Reading
Sponsor class: OTHER
Collaborators: name: Alpro Foundation
name: Wild Blueberry Association of North America
First posted: 2011-02-10
Enrollment: 10
Sex: MALE
Minimum age (years): 19
Maximum age (years): 40
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: BASIC_SCIENCE

Brief summary: Scientific question to be addressed: To determine the effects of acute blueberry ingestion on vascular function and blood pressure in humans

Hypothesis: Acute consumption of blueberry induces an improvement in blood pressure and vascular function through the impact of blueberry flavonoids on the vascular system.

Study objectives: To determine the dose-dependency of a blueberry drink on blood pressure and vascular function in healthy subjects and to determine pharmacokinetics of blueberry polyphenols

Detailed description: Coronary heart disease (CHD) remains one of the major causes of premature death in the world. There is now substantial evidence to indicate that the cells lining the inner surface of arteries play a major role in protection against the development and progression of CHD. This layer of cells is termed the endothelium and regulates vascular tone by promoting the expansion and contraction of the blood vessel. There are a variety of non-invasive techniques for measuring endothelial function.

Research provides evidence that consumption of a diet high in plant foods and rich in polyphenols is associated with a reduction in incidence of coronary heart disease (CHD). Polyphenols, of which the flavonoids are the largest group, are thought to play a role in the reduction of incidence of chronic diseases such as cardiovascular disease and stroke. Recent studies in humans show that flavonoid-rich foods improve peripheral blood flow and surrogate markers of cardiovascular function. These effects were associated with acute elevations in the levels of circulating nitric oxide species, an enhanced flow mediated dilatation (FMD) response of conduit arteries, and an augmented microcirculation. Increases in circulating nitric oxide species in response to flavonoid ingestion suggest that circulating flavonoids (and/or their metabolic forms) may exert positive effects on vascular tone.

The purpose of this study is to assess the impact of acute flavonoid intake on postprandial vascular reactivity of healthy volunteers. Specifically, the investigators plan to perform a randomised, double blind, cross-over human intervention trial using a blueberry drink to investigate the dose-dependent effects of blueberries using a range of techniques to measure endothelial function. The study will not only measure the acute effects of flavonoid ingestion on vascular reactivity but will also assess flavonoid and metabolite levels in blood and urine and other endothelial markers.

Eligibility criteria: Inclusion Criteria:

* Male
* A signed consent form
* Age 19-40 years old
* Body mass index - 18.5-30 kg/m2

Exclusion Criteria:

* Blood pressure \> 150/90 mmHg
* Haemoglobin (anaemia marker) \< 125 g/l
* Gamma GT (liver enzymes) \> 80 IU/l
* Cholesterol \> 6.5 mmol/l
* Had suffered a myocardial infarction or stroke in the previous 12 months
* Suffers from any reproductive disorder
* Suffers from any blood-clotting disorder
* Suffers from any metabolic disorders (e.g. diabetes or any other endocrine or liver diseases)
* Any dietary restrictions or on a weight reducing diet
* Drinking more than 21 units per week
* On any medication affecting blood clotting
* On any vitamin supplements/fish oil capsules
* Smoking
* Vegetarians or vegans

Primary outcomes:
measure: Flow-mediated dilation
timeFrame: 0-6 hours after consumption
Secondary outcomes:
measure: Blueberry polyphenols pharmacokinetics
timeFrame: 0- 24 h after consumption
measure: Blood Pressure
timeFrame: 0-6 hours after consumption
measure: Laser Doppler Iontophoresis
timeFrame: 0-6 hours after consumption
Other outcomes:
Locations:
city: Reading
country: United Kingdom
facility: University of Reading
state: Berkshire
Study officials:
affiliation: University of Reading
name: Jeremy Spencer, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Rodriguez-Mateos A, Rendeiro C, Bergillos-Meca T, Tabatabaee S, George TW, Heiss C, Spencer JP. Intake and time dependence of blueberry flavonoid-induced improvements in vascular function: a randomized, controlled, double-blind, crossover intervention study with mechanistic insights into biological activity. Am J Clin Nutr. 2013 Nov;98(5):1179-91. doi: 10.3945/ajcn.113.066639. Epub 2013 Sep 4.