The Effects of Cocoa Flavanols on Insulin Resistance in an 'At-risk' Population

This study has been completed.
Sponsor:
Collaborator:
Mars, Inc.
Information provided by (Responsible Party):
University of Nottingham
ClinicalTrials.gov Identifier:
NCT01201590
First received: September 30, 2009
Last updated: July 14, 2014
Last verified: July 2014
  Purpose

The aim of the current study is to investigate the ability of antioxidants found in cocoa ('flavanols') to increase the body's sensitivity to the hormone insulin. 32 overweight or mildly obese women, who are otherwise healthy, will be recruited. Subjects will attend the laboratory on 3 occasions after fasting from midnight. The 1st visit is a medical screening, with laboratory visits 2 and 3 separated by 4 weeks, during which time subjects will consume a cocoa drink (containing either high or low amounts of flavanols) twice a day. Subjects will record their food intake for 3-days before visit 2 and in week 3 of consuming the cocoa. They will also eat a diet of standard macronutrient composition for 3 days before visits 2 and 3. During the 5 hour laboratory visits, subjects will have a scan to assess their body composition using a low-dose x-ray machine (Dual Energy X-ray Absorptiometry; DEXA), and have their insulin sensitivity measured using a 3 hour hyperinsulinemic, euglycaemic Clamp.


Condition Intervention
Insulin Resistance
Dietary Supplement: High Flavanol Cocoa
Dietary Supplement: Low Flavanol Cocoa

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Parallel Assignment
Masking: Double Blind (Subject, Investigator, Outcomes Assessor)
Primary Purpose: Basic Science
Official Title: The Effects of Cocoa Flavanols on Insulin Resistance in at 'At-risk' Population

Resource links provided by NLM:


Further study details as provided by University of Nottingham:

Primary Outcome Measures:
  • Change in Insulin sensitivity 'M' value (mg glucose disposal from the blood/kg body weight/min), [ Time Frame: after 28 days of supplementation ] [ Designated as safety issue: No ]
    Insulin sensitivity calculated from glucose disposal during a hyperinsulinemic, euglycemic glucose clamp


Secondary Outcome Measures:
  • Change in Glucose Oxidation rate [ Time Frame: after 28 days of supplementation ] [ Designated as safety issue: No ]
    Measured by ventilated hood indirect calorimetry during the glucose clamp.


Enrollment: 32
Study Start Date: March 2009
Study Completion Date: October 2010
Primary Completion Date: July 2010 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: High Flavanol Cocoa
609mg cocoa flavanols per 24g serving
Dietary Supplement: High Flavanol Cocoa
cocoa consumed as a 24g dairy based cocoa drink mix, twice a day (mid-morning & early evening on an empty stomach), for 4 weeks.
Placebo Comparator: Low flavanol cocoa
13mg cocoa flavanols per 24g serving
Dietary Supplement: Low Flavanol Cocoa
cocoa consumed as a 24g dairy based cocoa drink mix, twice a day (mid-morning & early evening on an empty stomach), for 4 weeks.

Detailed Description:

Background; Overweight and mild obesity are associated with insulin resistance and mild elevations in lipid risk factors which are not usually sufficiently abnormal to merit treatment. Such people are encouraged to lose weight to reduce their risk of progressing to type 2 diabetes and coronary heart disease, but there is clearly a potential role for dietary modifications to maximize any potential benefit of this weight loss. Cocoa flavanols (CF) are known to have vascular effects which might enhance substrate delivery to metabolically active tissues, and thus improve insulin sensitivity.

Aims; This randomized, double blind, placebo controlled, parallel design study aims to investigate the longer term effects of CF intake on insulin sensitivity. It is hypothesized that studying otherwise healthy overweight and mildly obese subjects, with evidence of fasting insulin resistance, would show whether there was potential benefit of CF in an 'at risk' population.

Experimental protocol and methods; 32 overweight or obese women (Body Mass Index 27-35), who are otherwise healthy, will be recruited onto the study. They will attend the 'David Greenfield Human Physiology' laboratories on 3 convenient mornings, following an overnight fast. The 1st visit is a medical screening and will involve signing a consent form, completing a medical screening and food frequency questionnaire, having height, weight, hip/waist circumference measurements taken and a 10ml sample of blood taken for routine analysis. Subjects will then be asked to complete a 3-day diet diary for macronutrient assessment and to consume a diet providing 50% of energy as carbohydrate for 3 days prior to the 2nd laboratory visit. This 2nd visit will involve having a DEXA body composition scan and a 3-hour hyperinsulinaemic, euglycaemic glucose clamp. Starting on the following morning, subjects will then consume a cocoa drink (containing either 450mg or 25mg of CF) twice a day for 28 days. A 3-day diet diary for macronutrient assessment will be recorded during week 3 of taking the cocoa and a standardized diet will be consumed for 3 days prior to the final laboratory visit, as before. This 3rd visit will be identical to visit 2 and occur immediately after 28days of taking the cocoa.

Measurable end points Insulin sensitivity 'M' value (mg glucose disposal from the blood/kg body weight.min), Respiratory exchange ratio, Resting metabolic rate, Homeostatic model assessment for insulin resistance (HOMA-IR) Body composition (DEXA) Macronutrient composition of the diet before and during the intervention period

  Eligibility

Ages Eligible for Study:   18 Years to 50 Years
Genders Eligible for Study:   Female
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • female,
  • aged > 18 years,
  • pre-menopausal,
  • Body Mass Index (BMI)27-35,
  • homeostatic model assessment-Insulin Resistance(HOMA-IR)value > 1.5,
  • daily consumption of caffeine containing foods/drinks

Exclusion Criteria:

  • pregnant or breast feeding,
  • any metabolic or endocrine abnormalities,
  • clinically significant abnormalities on screening,
  • fasting glucose > 6.0mmol/l,
  • taking medication other than the contraceptive pill,
  • herbal supplement use,
  • food allergies related to the investigational product (cocoa, peanuts, milk)
  • sensitivity to methylxanthines (e.g., caffeine, theobromine)
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01201590

Locations
United Kingdom
David Greenfield Physiology Laboratories, University of Nottingham
Nottingham, Notts, United Kingdom, NG72UH
Sponsors and Collaborators
University of Nottingham
Mars, Inc.
Investigators
Principal Investigator: Ian A Macdonald, PhD University of Nottingham
  More Information

No publications provided

Responsible Party: University of Nottingham
ClinicalTrials.gov Identifier: NCT01201590     History of Changes
Other Study ID Numbers: 1000165377
Study First Received: September 30, 2009
Last Updated: July 14, 2014
Health Authority: United Kingdom: Research Ethics Committee

Keywords provided by University of Nottingham:
Insulin resistance
obesity
cocoa
women

Additional relevant MeSH terms:
Insulin Resistance
Hyperinsulinism
Glucose Metabolism Disorders
Metabolic Diseases
Insulin
Hypoglycemic Agents
Physiological Effects of Drugs
Pharmacologic Actions

ClinicalTrials.gov processed this record on July 28, 2014