Effect of Blueberries on Vascular Function in Healthy Men
Condition: Healthy
Study type: Interventional

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.
    

Intervention name(s): Blueberries
Intervention type(s): Dietary Supplement
Intervention description(s): low dose: 31.4 g of freeze dried blueberry reconstituted in water medium dose: 57 g of freeze dried blueberry reconstituted in water high dose: 80 g of freeze dried blueberry reconstituted in water Placebo: sugars and vitamin c match control in water Frequency:1 single time Total Duration: 3 days study over 3 weeks period
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Basic Science
Keywords: blueberries; vascular function; FMD; Blood pressure; Laser Doppler; pharmacokinetics; absorption; metabolism; polyphenols; flavonoids