Effect of Polyphenol-rich Dark Chocolate on Obesity

Effect of Polyphenols on Glucoregulatory Biomarkers, Blood Pressure and Lipid Profile in Overweight and Obese Subjects

This study aims to investigate the effect of polyphenol-rich dark chocolate (DC) on insulin resistance, adiponectin , blood pressure (BP), lipid profile in obese subjects and determine possible associations between all assessed parameters.

It hypothesizes that consumption of polyphenol-rich Dc could lower fasting glucose levels, insulin resistance and improve BP, total cholesterol, low-density lipoprotein (LDL) and triglycerides while increasing adiponectin and high-density lipoprotein (HDL) in overweight or obese individuals.

Study Overview

• Status: Unknown
• Conditions: Obesity
• Intervention / Treatment: Dietary supplement: placebo; Dietary supplement: Acticoa polyphenol-rich dark chocolate

Detailed Description

It is well acknowledged that the main mechanism by which cocoa and DC polyphenols improve fasting glucose levels, insulin sensitivity, BP and lipid profile in healthy individuals and those with hypertension and/or impaired glucose-tolerance, involves increased nitric oxide (NO) bioavailability. NO is essential for the regulation of blood pressure, glucose and lipid balance. This is evident in that e-NOsynthase knockout mice exhibit insulin resistance, hypertension and hyperlipidemia, a cluster of diseases that is also observed in the metabolic syndrome. Recently, it was shown that adiponectin regulates eNOsynthase activity through the phosphatidylinositol 3-kinase-dependent pathway wherein eNOsynthase is phosphorylated by 5'-AMP-activated protein kinase at Ser1179 and that plasma adiponectin levels are inversely correlated with BMI, waist-to-hip ratio, fasting plasma glucose, insulin, triglyceride, hyperinsulinemia, and glucose intolerance and positively with HDL-cholesterol, but not BP. This suggests a strong link between impaired NO bioavailability, adiponectin levels and obesity. Indeed, apart from exhibiting impaired NO bioavailability, obese individuals also have decreased plasma adiponectin levels. Since cocoa and DC are known to modulate NO activity, investigating the impact of cocoa or DC polyphenols on adiponectin levels and observing a correlation between its levels and improved fasting glucose levels, insulin resistance, BP and lipid profile is essential in improving our understanding of the relationship between diet and health, particularly that polyphenols in apples, oolong and green tea polyphenols have been previously shown to influence adiponectin levels.

This study uses a randomised single-blind, placebo-controlled design. Following a 1-week run-in phase, each group will be randomised to one of the two groups: placebo-polyphenol-rich DC, polyphenol-rich DC-placebo. Subjects will follow each diet for 4weeks, after which they will cross-over to the next diet separated by a 2-week washout period and until each subject completes both interventions.

• Study Type: Interventional
• Enrollment (Anticipated): 50
• Phase: Phase 2

Contacts and Locations

Study Locations

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

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 50 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: Female

Description

Inclusion Criteria:

• Healthy female volunteers
• Aged 18-50 years
• Group 1 will consist of volunteers with BMI of 18-25 kg/m2
• Group 2 will consist of women with BMI of 25-35 kg/m2

Exclusion Criteria:

• Cardiovascular disease
• Hypertension
• Diabetes
• Smokers
• People taking dietary supplements
• Hypertension or cholesterol-lowering drugs
• Those with high cocoa or DC intake, soy or nut allergies

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: placebo dark chocolate; polyphenol-poor dark chocolate	Dietary supplement: placebo; polyphenol-free dark chocolate 20g to be distributed throughout the day for 4 weeks; Other Names: barry callebaut
Experimental: polyphenol-rich dark chocolate	Dietary supplement: Acticoa polyphenol-rich dark chocolate; 20g to be distributed throughout the day for 4 weeks; Other Names: barry callebaut, acticoa

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
adiponectin	week 0, 4, 6, 10

Secondary Outcome Measures

Outcome Measure	Time Frame
insulin sensitivity	week 0, 4, 6, 10
blood pressure	week 0, 4, 6, 10
lipid profile	week 0, 4, 6, 10

Collaborators and Investigators

• Sponsor: Queen Margaret University
• Investigators: Principal Investigator: suzana h almoosawi, BScHons HN, QMU

Study record dates

Study Major Dates

• Study Start: November 1, 2008
• Primary Completion (Anticipated): October 1, 2009
• Study Completion (Anticipated): December 1, 2009

Study Registration Dates

• First Submitted: December 29, 2008
• First Submitted That Met QC Criteria: December 29, 2008
• First Posted (Estimate): December 30, 2008

Study Record Updates

• Last Update Posted (Estimate): September 18, 2009
• Last Update Submitted That Met QC Criteria: September 17, 2009
• Last Verified: September 1, 2009

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Overnutrition; Nutrition Disorders; Overweight; Body Weight; Obesity
• Other Study ID Numbers: 1-salmoosawi