The Effect of Tea on Vascular Function and Insulin Sensitivity

Not Applicable

Completed

• Conditions: Insulin Resistance
• Interventions: Dietary Supplement: Green tea; Dietary Supplement: Placebo tea

• Registration Number: NCT02777853
• Lead Sponsor: Liverpool John Moores University

Brief Summary

The aim of this research is to explore changes in peripheral/cerebrovascular function and insulin sensitivity after a 7-day combination of physical activity reduction (-50% steps per day) and overfeeding (+50% kcal per day, comprising 65% fat) in healthy male volunteers, and examine whether daily intake of tea can prevent such changes.

Detailed Description

The aim of this study is to explore the impact of a 7-day 'unhealthy' lifestyle that combines physical activity reduction (-50% steps per day) and overfeeding (+50% kcal per day, comprising 65% fat) on peripheral (conduit artery and skin microvessels) and cerebrovascular function and insulin sensitivity in healthy male participants. Moreover, the investigators will explore whether the detrimental impact of this lifestyle can be mitigated by daily tea consumption (equivalent to 6 cups/day). To explore this hypothesis, the investigators will perform measurements of these parameters before and after 7-days of reduced physical activity and overfeeding, with and without the combination of daily tea ingestion.

Study Timeline

• Study Start: 2016-05
• Study First Submitted: 2016-05-17
• Study First Submitted QC: 2016-05-18
• Study First Posted: 2016-05-19
• Primary Completion: 2017-06
• Study Completion: 2017-07
• Status Verified: 2017-08
• Last Update Submitted: 2017-08-23
• Last Update Posted: 2017-08-24

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Male
• Target Recruitment: 12

Inclusion Criteria

• Aged 18-55 years
• Male
• Habitually active (>8,000 steps/day)
• Healthy

Exclusion Criteria

• Smokers
• Medical history of cardiovascular/metabolic disease
• Family history of cardiovascular disease (first degree relatives)
• On medication known to influence the cardiovascular system
• BMI of <18 or >30 kg/m2
• Known food allergies or special dietary requirements
• Vaccination (<1 week) due to induced systemic inflammatory reaction

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Active (green) tea	Green tea	Tea to be ingested 3 times per day for 7 days.
Placebo tea	Placebo tea	Tea to be ingested 3 times per day for 7 days.

Primary Outcome Measures

Name	Time	Method
Insulin sensitivity	Post 7 day intervention	This will be measured following a carbohydrate-rich meal tolerance test (MTT) after an overnight fast, combined with regular venous blood sampling of insulin and glucose.

Secondary Outcome Measures

Name	Time	Method
Vascular function	Post 7 day intervention	Peripheral vascular function will be measured via endothelial-dependent flow-mediated dilation (FMD) of the brachial and femoral arteries, with microcirculatory function being assessed using local thermal hyperaemia and laser Doppler flowmetry (LDF), in addition to full-field laser perfusion imaging (FLPI). Cerebrovascular function will be examined via transcranial Doppler.

Trial Locations

Locations (1)

Research Institute for Sport and Exercise Sciences (RISES), Liverpool John Moores University; 🇬🇧 Liverpool, United Kingdom