The Effects of Blueberry Anthocyanins on Insulin Resistance and Vascular, Lung and Cognitive Function in a Population With Metabolic Syndrome.
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Sponsor
- University of East Anglia
- Enrollment
- 144
- Locations
- 4
- Primary Endpoint
- Insulin resistance
Study Overview
Brief Summary
The purpose of this study is to determine the dose-dependent impact of 6 month freeze-dried blueberry powder intake on insulin sensitivity and resistance, cardiovascular disease risk factors, and lung and cognitive function in overweight and obese participants with metabolic syndrome. We will also examine acute post-prandial effects of blueberry intake (at baseline and at 6-months).
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Basic Science
- Masking
- Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Eligibility Criteria
- Ages
- 50 Years to 74 Years (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •Men and postmenopausal women (≥ 1 year since last menstruation)
- •50 to 75 years old
- •BMI of ≥ 25 kg/m2
- •3 characteristics of metabolic syndrome i.e: Waist circumference ≥ 102 cm for men, ≥ 88 cm for women; Triglycerides ≥ 1.7 mmol/L (or drug treatment for elevated triglycerides); HDL-cholesterol < 1.0 mmol/L for men, < 1.3 mmol/L for women (or drug treatment for low HDL-cholesterol); Blood pressure ≥ 130 mm Hg systolic and/or ≥ 85 mm Hg diastolic blood pressure; Fasting blood glucose ≥ 5.56 mmol/L
- •Successful biochemical, haematological and urinalysis assessment at screening
Exclusion Criteria
- •Current smokers, or ex-smokers ceasing < 6 months ago
- •Existing or significant past medical history of vascular disease or medical conditions likely to affect the study measures
- •Fructose intolerance or known allergies to the intervention treatments
- •On therapeutic diets or having experienced substantial weight loss within 3 months of screening
- •Taking flavonoid containing supplements (and unwilling to cease intake during, and 1 month preceding the trial)
- •Planning on altering consumption of vitamin supplements / fish oil capsules during the course of the study.
- •Prescribed hypoglycaemic, vasodilators or HRT medication.
- •Unsatisfactory biochemical, haematological or urinary assessment at screening, or measures considered to be counter indicative for the study
- •< 3 characteristics of the metabolic syndrome.
- •NB: REC approved NoSA granted to include those on anti-hypertensives (29JUL2014)
Arms & Interventions
Full dose blueberry
26g of freeze dried blueberry powder; equivalent to 2 portions of fresh blueberries per day.
Frequency: 26g per day.
Total duration: 6-month.
Intervention: Full dose blueberry (Other)
Half dose blueberry
26g of freeze dried powder; containing 13g of freeze dried blueberry powder and 13g of placebo comparator material; equivalent to 1 portion of fresh blueberries per day.
Frequency: 26g per day.
Total duration: 6-month.
Intervention: Half dose blueberry (Other)
Control
Matched control powder; matched for appearance, taste and sugar content.
Frequency: 26g per day.
Total duration: 6-month.
Intervention: Control (Other)
Outcomes
Primary Outcomes
Insulin resistance
Time Frame: Chronic (0 to 6 month)
Assessed, in the fasted state, via HOMA-IR calculation in all participants; indirect assessment.
Secondary Outcomes
- Insulin resistance(Chronic (0 to 6 month))
- Lung function(Chronic (0 to 6 month))
- Cognitive function(Chronic (0 to 6 month))
- Liver fat and blood flow assessment(Chronic (0 to 6 month))
- Blood pressure and blood vessel regulation(Chronic (0 to 6 month))
- Acute +24 hour effect of single (26g) intervention intake, given with high fat challenge(Chronic (0 to 6 month))
- Bio-availability(Chronic (0 to 6 month))
- Metabolite phenotype effects(Chronic (0 to 6 month))