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

University of East Anglia

Status: Completed

Conditions: Insulin Resistance; Metabolic Syndrome X

Treatments: Other: Control; Other: Full dose blueberry; Other: Half dose blueberry

Study type: Interventional

Funder types: Other

Identifiers

NCT02035592

R21478-C

Details and patient eligibility

About

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).

Enrollment: 144 estimated patients

Sex: All

Ages: 50 to 74 years old

Volunteers: No Healthy Volunteers

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)

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Quadruple Blind

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144 participants in 3 patient groups, including a placebo group

Full dose blueberry

Active Comparator group

Description:

26g of freeze dried blueberry powder; equivalent to 2 portions of fresh blueberries per day. Frequency: 26g per day. Total duration: 6-month.

Treatment:

Other: Full dose blueberry

Half dose blueberry

Active Comparator group

Description:

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.

Treatment:

Other: Half dose blueberry

Control

Placebo Comparator group

Description:

Matched control powder; matched for appearance, taste and sugar content. Frequency: 26g per day. Total duration: 6-month.

Treatment:

Other: Control