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

Insulin Resistance Clinical Trial

— CIRCLES  

Official title:

The Effects of Blueberry Anthocyanins on Insulin Resistance and Vascular, Lung and Cognitive Function in a Population With Metabolic Syndrome.

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT02035592
• Other study ID #: R21478-C
• Status: Completed
• Phase: N/A
• First received: January 10, 2014
• Last updated: September 28, 2017
• Start date: January 2014
• Est. completion date: November 7, 2016

Study information

• Verified date: January 2017
• Source: University of East Anglia
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial 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).

Recruitment information / eligibility

• Status: Completed
• Enrollment: 144
• Est. completion date: November 7, 2016
• Est. primary completion date: November 7, 2016
• Accepts healthy volunteers: No
• Gender: All
• Age group: 50 Years to 74 Years

Eligibility

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)

Related Conditions & MeSH terms

• Insulin Resistance
• Metabolic Syndrome X
• Syndrome

Intervention

Other:
• Full dose blueberry
Full dose: 26g of freeze dried blueberry powder to be incorporated into the habitual diet. Dietary restrictions will be observed (i.e. avoidance of blueberry, and restricted intake of anthocyanin rich foods) for 21 days prior to the first assessment visit and throughout the study.
• Half dose blueberry
Half dose: 26g of freeze dried powder (containing 13g of freeze dried blueberry powder and 13g of placebo comparator material) to be incorporated into the habitual diet. Dietary restrictions will be observed (i.e. avoidance of blueberry, and restricted intake of anthocyanin rich foods) for 21 days prior to the first assessment visit and throughout the study.
• Control
Control: 26g of placebo comparator material to be incorporated into the habitual diet. Dietary restrictions will be observed (i.e. avoidance of blueberry, and restricted intake of anthocyanin rich foods) for 21 days prior to the first assessment visit and throughout the study.

Locations

Country	Name	City	State
United Kingdom	Addenbrooke's hospital	Cambridge	Cambridgeshire
United Kingdom	Norfolk and Norwich University Hospital	Norwich	Norfolk
United Kingdom	Norwich Medical School University of East Anglia	Norwich	Norfolk
United States	Harvard School of Public Health	Boston	Massachusetts

Sponsors (2)

Lead Sponsor	Collaborator
University of East Anglia	Harvard School of Public Health

Countries where clinical trial is conducted

United States,  United Kingdom, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Insulin resistance	Assessed, in the fasted state, via HOMA-IR calculation in all participants; indirect assessment.	Chronic (0 to 6 month)
Secondary	Insulin resistance	Assessed in a sub-group via hyperinsulinemic euglycaemic clamp.	Chronic (0 to 6 month)
Secondary	Blood pressure and blood vessel regulation	Measurements taken of arterial stiffness, endothelial function and blood pressure.	Chronic (0 to 6 month)
Secondary	Lung function	Assessed via standard spirometry techniques and biological assessment of exhaled samples.	Chronic (0 to 6 month)
Secondary	Cognitive function	Assessed via a validated cognitive test battery.	Chronic (0 to 6 month)
Secondary	Liver fat and blood flow assessment	Assessment via 3T MRI in a sub-group of participants.	Chronic (0 to 6 month)
Secondary	Bio-availability	Flavonoid and metabolite levels will be assessed in blood and 24 hour urine samples.	Chronic (0 to 6 month)
Secondary	Metabolite phenotype effects	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.	Chronic (0 to 6 month)
Secondary	Acute +24 hour effect of single (26g) intervention intake, given with high fat challenge	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.	Chronic (0 to 6 month)