Effect of Polyphenol-rich Dark Chocolate on Insulin Sensitivity in Normal Weight and Overweight Adults

The purpose of the study is to determine the effect of polyphenol-rich dark chocolate on insulin sensitivity in normal weight and overweight adults.

Study Overview

• Status: Completed
• Conditions: Insulin Resistance
• Intervention / Treatment: Other: Polyphenol-rich Dark chocolate; Other: Placebo Dark chocolate

Detailed Description

Polyphenols may have several favourable effects on health. Dark chocolate (DC) is one of the highest sources of polyphenols in foods. The aim of the study is to determine the effect of polyphenol-rich dark chocolate on insulin sensitivity in normal weight and overweight adults. Seventy four volunteers with no history of hypertension, cardiovascular diseases or diabetes will be recruited. Participants will randomly receive 20g daily of one of the two different types of DC: Placebo DC (low in polyphenols) or DC rich in polyphenols (500mg) for a period of four weeks. Participants will be asked to make two appointments to the university clinical lab. Anthropometric measurements (height, weight, waist circumference), blood and saliva samples will be taken during each of the 2 visits. Compliance will be tested by the measure of total polyphenols in a 24-hour urine sample in some random samples before and at the end of the intervention. To monitor any fluctuations in the participants' diet or physical activity during the study period, a three-day diet diary and a physical activity questionnaire will be collected before the start of the study and after four weeks. Data will be analysed with an ANCOVA with time (pre- and post-) and treatment (DC and placebo) as between-subject factor.

• Study Type: Interventional
• Enrollment (Actual): 61
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • East Lothian
    • Musselburgh, East Lothian, United Kingdom, EH21 6UU
      • Queen Margaret University Lab

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Adults with no history of hypertension, diabetes and cardiovascular diseases
• BMI from 18-24.9 and BMI >25
• Males and Females
• Age: 18-65 years

Exclusion Criteria:

• Participants with cardiovascular diseases, hypertension or diabetes
• Smokers and heavy alcohol drinkers
• Participants taking any medications that affect insulin, cholesterol, triglycerides or blood pressure
• Participants taking dietary supplements containing high doses of antioxidants
• Postmenopausal women taking HRT (Hormone Replacement Therapy)
• Participants who recently participated or are currently on a weight management program
• Participants with regular consumption of cocoa or DC (> 1 serving/week)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Polyphenol-rich Dark chocolate; Dark chocolate with 500 mg of polyphenols	Other: Polyphenol-rich Dark chocolate; Participants will be asked to consume 20g of dark chocolate containing 500mg of polyphenols daily for a period of 4 weeks
Placebo Comparator: Placebo Dark chocolate; This chocolate contains little or no polyphenols	Other: Placebo Dark chocolate; Participants will be asked to consume 20g of dark chocolate containing little or no polyphenols for a period of 4 weeks

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Determine if the consumption of DC rich in polyphenols can induce a change in insulin sensitivity	Insulin sensitivity will be determined by determined by HOMA-IR (Homeostasis Model of Assessment - Insulin Resistance)	Baseline and week 4

Secondary Outcome Measures

Outcome Measure	Time Frame
Determine if the consumption of DC rich in polyphenols can induce a change in glucose levels	Baseline and week 4
Determine if the consumption of DC rich in polyphenols can induce a change in Lipid profile (TC, HDL, LDL & TG)	Baseline and week 4
Determine if the consumption of DC rich in polyphenols can induce a change in oxidized LDL levels	Baseline and week 4
Determine if the consumption of DC rich in polyphenols can induce a change in BMI and Waist circumference	Baseline and week 4
Determine if the consumption of DC rich in polyphenols can induce a change in blood pressure	Baseline and week 4
Determine if the consumption of DC rich in polyphenols can induce a change in salivary cortisol-to-cortisone ratio	Baseline and week 4
Determine if the consumption of DC rich in polyphenols can induce a change in high sensitivity CRP	Baseline and Week 4

Collaborators and Investigators

• Sponsor: Queen Margaret University
• Collaborators: Barry Callebaut
• Investigators: Study Director: Emad Al-Dujaili, PhD, Queen Margaret University

Study record dates

Study Major Dates

• Study Start: March 1, 2012
• Primary Completion (Actual): July 1, 2013
• Study Completion (Actual): July 1, 2013

Study Registration Dates

• First Submitted: December 10, 2012
• First Submitted That Met QC Criteria: December 12, 2012
• First Posted (Estimate): December 13, 2012

Study Record Updates

• Last Update Posted (Estimate): November 20, 2013
• Last Update Submitted That Met QC Criteria: November 19, 2013
• Last Verified: November 1, 2013

More Information

Terms related to this study

• Keywords: Diabetes type II, Insulin sensitivity
• Additional Relevant MeSH Terms: Glucose Metabolism Disorders; Metabolic Diseases; Immune System Diseases; Body Weight; Hyperinsulinism; Hypersensitivity; Insulin Resistance; Overweight
• Other Study ID Numbers: DC-Ins01