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

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

Detailed Description
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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.

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

Conditions
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Insulin Resistance

Intervention / Treatment
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* Other: Polyphenol-rich Dark chocolate
* Other: Placebo Dark chocolate


Participation Criteria
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Eligibility Criteria
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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)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

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


Arms and Interventions

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

What is the study measuring?
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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 | Measure Description | 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 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Diabetes type II, Insulin sensitivity