The Effect of Tea on Vascular Function and Insulin Sensitivity

August 23, 2017 updated by: Kirsty Woodward, Liverpool John Moores University

Can Tea Prevent Impairments in Vascular Function and Insulin Sensitivity Induced by 7-days Physical Inactivity and Overfeeding in Healthy Men

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.

Study Overview

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 Type

Interventional

Enrollment (Actual)

12

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

      • Liverpool, United Kingdom, L3 3AF
        • Research Institute for Sport and Exercise Sciences (RISES), Liverpool John Moores University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 55 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Male

Description

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 Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Active (green) tea
Tea to be ingested 3 times per day for 7 days.
The intervention product is regular green tea brewed with hot water in a large quantity. The tea obtained is dried and the powder, with added sugar, is distributed over sealed aluminium sachets (1 gram of powder per sachet). The product has been cleared for consumption by Unilever's Microbiology Department and the independent Safety and Environmental Assurance Centre of Unilever.
Other Names:
  • Camillia sinesis
Placebo Comparator: Placebo tea
Tea to be ingested 3 times per day for 7 days.
A product of similar colour and taste, but not the presumed actives of tea (polyphenols), is used as placebo. The product has been cleared for consumption by Unilever's Microbiology Department and the independent Safety and Environmental Assurance Centre of Unilever.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Insulin sensitivity
Time Frame: 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.
Post 7 day intervention

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Vascular function
Time Frame: 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.
Post 7 day intervention

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Collaborators

Investigators

  • Principal Investigator: Kirsty A Woodward, BSc, Liverpool John Moores University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

May 1, 2016

Primary Completion (Actual)

June 1, 2017

Study Completion (Actual)

July 1, 2017

Study Registration Dates

First Submitted

May 17, 2016

First Submitted That Met QC Criteria

May 18, 2016

First Posted (Estimate)

May 19, 2016

Study Record Updates

Last Update Posted (Actual)

August 24, 2017

Last Update Submitted That Met QC Criteria

August 23, 2017

Last Verified

August 1, 2017

More Information

Terms related to this study

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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