Green Tea Supplementation, Fat Oxidation and Body Composition in Overweight Individuals (GreenTea)

The Effect of Green Tea Supplementation Strategies on Fat Oxidation and Body Composition in Overweight Individuals

The purpose of this study is to investigate the effects of green tea extract (GTE) on fat oxidation, body composition and exercise performance in overweight individuals. The study will be conducted under laboratory conditions following an 8 week supplemental period. Participants will be required to attend the laboratory for a pre-screening/familiarisation trial followed by assessments at week 0 (baseline), week 2, 4 and 8. Across the intervention, participants will maintain habitual dietary intake and follow a prescribed exercise programme. Additionally participants will be randomised to either a placebo, green tea extract or GTE with antioxidant supplementation.

It is hypothesised that the addition of antioxidants with GTE will enhance fat oxidation in overweight individuals more than GTE or placebo. It is further hypothesised that such improvements in fat oxidation due to GTE will lead to improvements in both body composition variables and submaximal exercise performance (metabolic efficiency) in overweight, but otherwise healthy persons.

Study Overview

• Status: Completed
• Conditions: Overweight and Obesity; Fat Burn
• Intervention / Treatment: Dietary supplement: Placebo control; Dietary supplement: GTE 1; Dietary supplement: GTE 2

Detailed Description

The health benefits of polyphenols found in green tea (GT), the unfermented leaves of the tea plant, Camellia sinensis, are of current scientific interest. These health benefits, in part, relate to the bioactive catechin polyphenol content of GT, of which (-)-epigallocatechin-3-gallate (EGCG) can account for between 50-80% of the total catechin content. GT catechins have been proposed to influence metabolic and thermogenic activities in the short term, leading to enhanced fat oxidation capacity, although this has been disputed.

Research investigating GT extracts (GTE) and exercise have produced conflicting results. Modest EGCG dosage in the short term (270 mg·d-1 EGCG for 6 days, and 68 mg·d-1 EGCG for 3 weeks) did not alter metabolic or performance variables in healthy or endurance trained volunteers. However, the inclusion of 100.5 mg·d-1 EGCG over a 10 week training period enhanced whole-body metabolic efficiency elsewhere. One confounding factor though is the use of caffeinated GTE in these studies. When decaffeinated GTE (dGTE) has been employed, 366 mg EGCG was found to acutely increase fat oxidation by 17%. Indeed a recent publication from our research group investigating the short term use of dGTE demonstrated positive changes in fat oxidation in healthy volunteers. However, less is known as to whether dGTE (or indeed combinations of dGTE with antioxidant nutrients which may improve GTE bioavailability) could provide similar results in overweight or sedentary individuals embarking on an exercise programme.

The aim of this research proposal is therefore to assess the impact of two GTE strategies on fat oxidation, cardiometabolic health, visceral fat reduction, and exercise performance in a healthy, but overweight cohort undertaking a standardised exercise training programme.

Research Questions:

Q1: Does regular consumption of dGTE favourably enhance fat oxidation and/or improve variables associated with cardiometabolic health and body composition in comparison to a placebo supplement in healthy, but overweight individuals? Q2: Does a dGTE complex (including key antioxidant nutrients) enhance fat oxidation and/or improve variables associated with cardiometabolic health and body composition more so than dGTE or placebo supplementation in healthy, but overweight individuals?

This study will involve participants attending sessions at Compass House, ARU, undertaking the following:

• Baseline trial: all participants will attend a subject briefing, provide written, informed consent prior to participation. Following this, all participants will undertake a baseline test for maximal fat oxidation rates (FATmax) and oxygen uptake using a standardised incremental cycling exercise protocol and expired air analysis
• Intervention period: participants will be randomly assigned to either dGTE (400mg EGCG daily), dGTE with antioxidants (150mg quercetin, 150mg alpha-lipoic acid) or placebo for 8 weeks. During this period, participants will undertake regular aerobic exercise (3x/ week; 45mins; at ~ FATmax intensity)
• Experimental evaluation of progress will be assessed at weeks 0,2,4, and 8. During laboratory visits, participants will be required to have a single venepuncture blood sample, assessment of blood pressure/ body composition (skinfold, bioelectrical impedance, waist circumference), assessment of FATmax, and assessment of fat oxidation during steady state exercise at FATmax.

• Study Type: Interventional
• Enrollment (Actual): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Cambridge, United Kingdom, CB1 1PT
    • Anglia Ruskin University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 55 years (ADULT)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

1. Men and women, UK based, above 18 years of age
2. Below 45 years of age (for men) and below 55 years of age (for women)
3. Baseline maximal oxygen uptake >25ml/kg/min and <45ml/kg/min representative of normal (but not high) fitness levels; and a body mass index (BMI) >25kg/m2 and <33kg/m2
4. All participants: No known history (including family history) of heart abnormalities, hypertension, coronary heart disease or diabetes (determined from pre-study health screen questionnaire)
5. All participants: No known history of liver related disorders (e.g. hepatitis, Wilsons disease, cirrhosis).
6. All participants: Not currently suffering from any musculo-skeletal injury, or any other reason that may prevent participation in cardiovascular exercise
7. All participants: Have not suffered from recent viral infections ie: influenza (defined within the prior 2 months)
8. All participants: Not suffering from any known blood related disorders, including blood coagulation abnormalities, or have any adverse reactions to blood taking
9. All participants: Not taking any prescribed or over-the-counter medication which may influence exercise training (with the exception of inhalers for exercise induced asthma or contraceptive pill)
10. All participants: Not consuming or prepared to refrain from consumption, any commercial supplementation which conflicts with the study parameters ie: creatine, other green tea or weight loss products.

Exclusion Criteria:

1. Anyone below the age of 18 years, or above 45 years (for men) and 55 years (for women) - based on exercise testing guidelines by the American College of Sports Medicine (ACSM).
2. Those who do not meet the criteria for baseline maximal oxygen uptake or BMI assessment
3. All participants: anyone with a known history (including family history) of heart abnormalities, hypertension, coronary heart disease or diabetes (determined from pre-study health screen questionnaire)
4. All participants: anyone with a known previous history of liver related disorders.
5. All participants: Anyone suffering from a current musculo-skeletal injury, or any other reason that may prevent participation in cardiovascular exercise
6. All participants: those suffering from recent viral infections ie: influenza (defined within the prior 2 months)
7. All participants: Those with known blood related disorders, including blood coagulation abnormalities, or have any adverse reactions to blood taking. This includes any participant who has or potentially has an infectious disease, inc. HIV, and all types of hepatitis.
8. All participants: Anyone taking any prescribed or over-the-counter medication which may influence exercise training (with the exception of inhalers for exercise induced asthma or contraceptive pill)
9. All participants: Anyone consuming or not prepared to refrain from consumption, any commercial supplementation which conflicts with the study parameters ie: creatine, other green tea or weight loss products.
10. FEMALE ONLY: Any participant who is, suspects they may be or becomes pregnant during the study.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: BASIC_SCIENCE
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: DOUBLE

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
PLACEBO_COMPARATOR: Placebo group; Placebo - capsulated, colour matched potato starch (~450mg per capsule) - provided by Biocare Ltd., UK using standard 00 vegetable capsules (hydroxypropyl methylcellulose). Dosage: 2 divided doses (1 capsule mid morning, 1 capsule mid afternoon) - daily for 8 weeks.	Dietary supplement: Placebo control; 8 week supplementation period, with participants consuming 2 capsules per day containing potato starch; Other Names: Placebo
EXPERIMENTAL: Green tea 1; Capsulated decaffeinated green tea extract (dGTE) (standardised to 70% EGCG concentration, 571mg total per day, containing 400mg EGCG - provided by Biocare Ltd., UK using standard 00 vegetable capsules (hydroxypropyl methylcellulose). Dosage: 2 divided doses (1 capsule mid morning, 1 capsule mid afternoon) - daily for 8 weeks.	Dietary supplement: GTE 1; 8 week supplementation period, with participants consuming 2 capsules per day containing green tea extract (571mg/d); Other Names: Decaffeinated green tea extract
EXPERIMENTAL: Green tea 2; Capsulated decaffeinated green tea extract (dGTE) (standardised to 70% EGCG concentration, 571mg total per day, containing 400mg EGCG + 150mg quercitin and 150mg alpha lipoic acid - provided by Biocare Ltd., UK using standard 00 vegetable capsules (hydroxypropyl methylcellulose). Dosage: 2 divided doses (1 capsule mid morning, 1 capsule mid afternoon) - daily for 8 weeks.	Dietary supplement: GTE 2; 8 week supplementation period, with participants consuming 2 capsules per day containing green tea extract with additional antioxidants (150mg of quercitin and 150mg of alpha lipoic acid); Other Names: Decaffeinated green tea extract and antioxidants

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fat oxidation (max)	Assessment of maximal fat oxidation rate (via expired air) during incremental exercise	Change from Baseline maximal fat oxidation at 1 month
Fat oxidation (max)	Assessment of maximal fat oxidation rate (via expired air) during incremental exercise	Change from Baseline maximal fat oxidation at 2 months
Fat oxidation (min)	Assessment of exercise intensity at which point fat oxidation is negligable	Change from Baseline minimum fat oxidation at 1 month
Fat oxidation (min)	Assessment of exercise intensity at which point fat oxidation is negligable	Change from Baseline minimum fat oxidation at 2 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Height	Assessment of height (in metres)	Change from baseline height at 1 month
Height	Assessment of height (in metres)	Change from baseline height at 2 months
Weight	Assessment of weight (in kilograms)	Change from baseline weight at 1 month
Weight	Assessment of weight (in kilograms)	Change from baseline weight at 2 months
Bodyfat percentage	Assessment of bodyfat (%)	Change from baseline bodyfat percentage at 1 month
Bodyfat percentage	Assessment of bodyfat (%)	Change from baseline bodyfat percentage at 2 months
Waist to hip ratio	Assessment of waist to hip ratio (cm)	Change from baseline waist to hip ratio at 1 month
Waist to hip ratio	Assessment of waist to hip ratio (cm)	Change from baseline waist to hip ratio at 2 months
Body mass index	Assessment of body mass index or BMI (measured in kilograms per metre squared)	Change from baseline BMI at 1 month
Body mass index	Assessment of body mass index or BMI (measured in kilograms per metre squared)	Change from baseline BMI at 2 months
Central abdomen depth	Assessment of central abdomen depth (in cm)	Change from baseline central abdominal depth at 1 month
Central abdomen depth	Assessment of central abdomen depth (in cm)	Change from baseline central abdominal depth at 2 months
Blood cholesterol	Assessment of total cholesterol, triglycerides, HDL-c and LDL-c (all in mmol/L)	Change from Baseline at 1 month
Blood cholesterol	Assessment of total cholesterol, triglycerides, HDL-c and LDL-c (all in mmol/L)	Change from Baseline at 2 months
Blood glucose	Assessment of blood glucose (in mmol/L)	Change from Baseline blood glucose at 1 month
Blood glucose	Assessment of blood glucose (in mmol/L)	Change from Baseline blood glucose at 2 months
Blood insulin	Assessment of blood glucose (in pmol/L)	Change from Baseline blood insulin at 1 month
Blood insulin	Assessment of blood glucose (in pmol/L)	Change from Baseline blood insulin at 2 months
Blood leptin	Assessment of blood leptin (in ng/ml)	Change from Baseline blood leptin at 1 month
Blood leptin	Assessment of blood leptin (in ng/ml)	Change from Baseline blood leptin at 2 months
Blood adiponectin	Assessment of blood adiponectin (in ug/ml)	Change from Baseline blood adiponectin at 1 month
Blood adiponectin	Assessment of blood adiponectin (in ug/ml)	Change from Baseline blood adiponectin at 2 months
Blood fatty acids and glycerol	Assessment of blood free fatty acids and glycerol (both in umol/L)	Change from Baseline at 1 month
Blood fatty acids and glycerol	Assessment of blood free fatty acids and glycerol (both in umol/L)	Change from Baseline at 2 months
Blood liver enzymes	Assessment of blood liver enzymes including alanine aminotransferase(ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) (all measured in U/L)	Change from baseline at 1 month
Blood liver enzymes	Assessment of blood liver enzymes including alanine aminotransferase(ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) (all measured in U/L)	Change from baseline at 2 months
Blood bilirubin	Assessment of blood concentration of bilirubin (in umol/L)	Change from baseline bilirubin at 1 month
Blood bilirubin	Assessment of blood concentration of bilirubin (in umol/L)	Change from baseline bilirubin at 2 months
Respiratory measures (oxygen, carbon dioxide) during steady state exercise	Assessment of expired oxygen and carbon dioxide (in litres per minute)	Change from baseline at 1 month
Respiratory measures (oxygen, carbon dioxide) during steady state exercise	Assessment of mean expired oxygen and carbon dioxide (in litres per minute)	Change from baseline at 2 months

Collaborators and Investigators

• Sponsor: Anglia Ruskin University

Publications and helpful links

General Publications

• Dulloo AG, Duret C, Rohrer D, Girardier L, Mensi N, Fathi M, Chantre P, Vandermander J. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr. 1999 Dec;70(6):1040-5. doi: 10.1093/ajcn/70.6.1040.
• Roberts JD, Roberts MG, Tarpey MD, Weekes JC, Thomas CH. The effect of a decaffeinated green tea extract formula on fat oxidation, body composition and exercise performance. J Int Soc Sports Nutr. 2015 Jan 21;12(1):1. doi: 10.1186/s12970-014-0062-7. eCollection 2015.
• Hursel R, Viechtbauer W, Westerterp-Plantenga MS. The effects of green tea on weight loss and weight maintenance: a meta-analysis. Int J Obes (Lond). 2009 Sep;33(9):956-61. doi: 10.1038/ijo.2009.135. Epub 2009 Jul 14.
• Hursel R, Westerterp-Plantenga MS. Thermogenic ingredients and body weight regulation. Int J Obes (Lond). 2010 Apr;34(4):659-69. doi: 10.1038/ijo.2009.299. Epub 2010 Feb 9.
• Ichinose T, Nomura S, Someya Y, Akimoto S, Tachiyashiki K, Imaizumi K. Effect of endurance training supplemented with green tea extract on substrate metabolism during exercise in humans. Scand J Med Sci Sports. 2011 Aug;21(4):598-605. doi: 10.1111/j.1600-0838.2009.01077.x. Epub 2010 Mar 10.
• Venables MC, Hulston CJ, Cox HR, Jeukendrup AE. Green tea extract ingestion, fat oxidation, and glucose tolerance in healthy humans. Am J Clin Nutr. 2008 Mar;87(3):778-84. doi: 10.1093/ajcn/87.3.778.
• Ryu OH, Lee J, Lee KW, Kim HY, Seo JA, Kim SG, Kim NH, Baik SH, Choi DS, Choi KM. Effects of green tea consumption on inflammation, insulin resistance and pulse wave velocity in type 2 diabetes patients. Diabetes Res Clin Pract. 2006 Mar;71(3):356-8. doi: 10.1016/j.diabres.2005.08.001. Epub 2005 Sep 19.
• Maki KC, Reeves MS, Farmer M, Yasunaga K, Matsuo N, Katsuragi Y, Komikado M, Tokimitsu I, Wilder D, Jones F, Blumberg JB, Cartwright Y. Green tea catechin consumption enhances exercise-induced abdominal fat loss in overweight and obese adults. J Nutr. 2009 Feb;139(2):264-70. doi: 10.3945/jn.108.098293. Epub 2008 Dec 11.
• Feng WY. Metabolism of green tea catechins: an overview. Curr Drug Metab. 2006 Oct;7(7):755-809. doi: 10.2174/138920006778520552.
• Hodgson AB, Randell RK, Jeukendrup AE. The effect of green tea extract on fat oxidation at rest and during exercise: evidence of efficacy and proposed mechanisms. Adv Nutr. 2013 Mar 1;4(2):129-40. doi: 10.3945/an.112.003269.
• Dean S, Braakhuis A, Paton C. The effects of EGCG on fat oxidation and endurance performance in male cyclists. Int J Sport Nutr Exerc Metab. 2009 Dec;19(6):624-44. doi: 10.1123/ijsnem.19.6.624.
• Eichenberger P, Colombani PC, Mettler S. Effects of 3-week consumption of green tea extracts on whole-body metabolism during cycling exercise in endurance-trained men. Int J Vitam Nutr Res. 2009 Jan;79(1):24-33. doi: 10.1024/0300-9831.79.1.24.
• Achten J, Jeukendrup AE. Maximal fat oxidation during exercise in trained men. Int J Sports Med. 2003 Nov;24(8):603-8. doi: 10.1055/s-2003-43265.

Study record dates

Study Major Dates

• Study Start (ACTUAL): December 1, 2018
• Primary Completion (ACTUAL): December 1, 2019
• Study Completion (ACTUAL): March 1, 2020

Study Registration Dates

• First Submitted: November 5, 2020
• First Submitted That Met QC Criteria: November 9, 2020
• First Posted (ACTUAL): November 13, 2020

Study Record Updates

• Last Update Posted (ACTUAL): November 13, 2020
• Last Update Submitted That Met QC Criteria: November 9, 2020
• Last Verified: November 1, 2020

More Information

Terms related to this study

• Keywords: Green Tea; Exercise Metabolism
• Additional Relevant MeSH Terms: Body Weight; Overweight; Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Protective Agents; Antioxidants
• Other Study ID Numbers: FST/FREP/17/703

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No