This study aims to find out if consuming a single dose of blueberries, rich in anthocyanins, within an energy dense meal, improves blood vessel function and biomarkers of heart health. The study specifically aims to confirm if differences in how individuals process the bioactive compounds in blueberries, called anthocyanins, has an influence on heart health. The investigators will assess the effects of eating one portion of blueberries on vascular health over a 48hour period, and will track the breakdown compounds within blood and urine, to see if health effects are related to metabolism.
The primary aim of this cross-over designed, placebo controlled, acute dietary intervention study, is to prospectively recruit participants on the basis of anthocyanin metabolism profiles (based on profiles confirmed in our previous studies) following a 'blueberry challenge'. Acute cardio and metabolic function responses will be assessed (by metaboliser profile), following an energy dense test meal with/without the addition of blueberries. Participants will be healthy, but overweight and obese (BMI inclusion: ≥ 25kg/m2) men and women (aged 50 y to 80 y), who will initially undertake a 'blueberry challenge' by consuming a single dose of freeze dried blueberries. Anthocyanin metaboliser type will be profiled from the analysis of metabolites within urine, collected for 48h following the 'challenge'. A total of 70 participants will complete the intervention (n=35 FAST and n=35 SLOW metabolisers) which consists of two, test meal periods (separated by at least 7d and allocated in random order); 1) energy dense test meal plus freeze dried blueberries, 2) energy dense test meal plus an isocaloric matched placebo material. Urine samples and ambulatory blood pressure measures will be collected for 24h prior to, and then over the 48h period which follows the test meal intake. Further assessment of vascular and metabolic function will be made at pre-defined times over the 48h postprandial period. Dietary restrictions to abstain from blueberries and reduce the anthocyanin intake level, will be applied for 5d before each test meal intake. In addition, all food and drink will be provided for a 4d period (2d before and during the 48h following the energy dense test meal) to further control the intake of flavonoids and to standardise the influence of background diet on metabolism profile.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
TRIPLE
Enrollment
49
36 g of freeze-dried blueberry powder to be mixed with milk and served together with an energy-dense meal.
36 g of isocaloric placebo, matched for sugars to be mixed with milk and served together with an energy-dense meal.
Quadram Institute Clinical Research Facility; a partnership facility of the NHS, UEA and QIB
Norwich, Norfolk, United Kingdom
Brachial artery endothelial function
percentage maximum dilatation assessed via flow mediated dilation (%FMD): (diametermax-diameterbaseline) / diameterbaseline×100.
Time frame: assessed at 0, 1.5, 3, 6, 24, 48 hours after intervention intake
Office blood pressure
Measurements of blood pressure
Time frame: Assessed at 0, 3, 6, 24, 48 hours after intervention intake.
Bioavailability - serum
Assessment of flavonoid and metabolite levels in blood samples
Time frame: Measured prior to, and then at +20, +40, +60, +90, +120, +180, +270 and +360 minutes, +24 hours and +48 hours following the energy dense meal intake.
Postprandial Insulin response
Assessment of postprandial insulin control
Time frame: Measured prior to, and then at +20, +40, +60, +90, +120, +180, +270 and +360 minutes, +24 hours and +48 hours following the energy dense meal intake.
Total cholesterol
Assessment of blood cholesterol
Time frame: Measured prior to, and then at +20, +40, +60, +90, +120, +180, +270 and +360 minutes, +24 hours and +48 hours following the energy dense meal intake.
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