The Health Effects of Blueberry Anthocyanins in Metabolic Syndrome (the CIRCLES-study)

Not Applicable

Completed

• Conditions: Metabolic Syndrome X; Insulin Resistance
• Interventions: Other: Half dose blueberry; Other: Full dose blueberry; Other: Control

• Registration Number: NCT02035592
• Lead Sponsor: University of East Anglia

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).

Detailed Description

Not available

Study Timeline

• Study Start: 2014-01
• Study First Submitted: 2014-01-10
• Study First Submitted QC: 2014-01-10
• Study First Posted: 2014-01-14
• Primary Completion: 2016-11-07
• Study Completion: 2016-11-07
• Status Verified: 2017-01
• Last Update Submitted: 2017-09-28
• Last Update Posted: 2017-09-29

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 144

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

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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)

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Half dose blueberry	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.
Full dose blueberry	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.
Control	Control	Matched control powder; matched for appearance, taste and sugar content. Frequency: 26g per day. Total duration: 6-month.

Primary Outcome Measures

Name	Time	Method
Insulin resistance	Chronic (0 to 6 month)	Assessed, in the fasted state, via HOMA-IR calculation in all participants; indirect assessment.

Secondary Outcome Measures

Name	Time	Method
Insulin resistance	Chronic (0 to 6 month)	Assessed in a sub-group via hyperinsulinemic euglycaemic clamp.
Lung function	Chronic (0 to 6 month)	Assessed via standard spirometry techniques and biological assessment of exhaled samples.
Cognitive function	Chronic (0 to 6 month)	Assessed via a validated cognitive test battery.
Liver fat and blood flow assessment	Chronic (0 to 6 month)	Assessment via 3T MRI in a sub-group of participants.
Blood pressure and blood vessel regulation	Chronic (0 to 6 month)	Measurements taken of arterial stiffness, endothelial function and blood pressure.
Acute +24 hour effect of single (26g) intervention intake, given with high fat challenge	Chronic (0 to 6 month)	Insulin resistance, lipaemia, vascular, cognitive and lung function measured pre- and post-intervention in combination with a high fat challenge in a sub-group of participants. Urine samples and blood samples (over a 24 hour period) will be taken for biomarker analysis.
Bio-availability	Chronic (0 to 6 month)	Flavonoid and metabolite levels will be assessed in blood and 24 hour urine samples.
Metabolite phenotype effects	Chronic (0 to 6 month)	The gut microbiome will be assessed from faecal sample collection and the impact on metabolism and of genotype, will be assessed via a targeted approach.

Trial Locations

Locations (4)

Norfolk and Norwich University Hospital; 🇬🇧 Norwich, Norfolk, United Kingdom

Addenbrooke's hospital; 🇬🇧 Cambridge, Cambridgeshire, United Kingdom

Harvard School of Public Health; 🇺🇸 Boston, Massachusetts, United States

Norwich Medical School University of East Anglia; 🇬🇧 Norwich, Norfolk, United Kingdom