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Completed

NCT Number: NCT02777853

The Effect of Tea on Vascular Function and Insulin Sensitivity

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.

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Key information

Conditions

Insulin Resistance Behavior Glucose Metabolism Disorders Hyperinsulinism Metabolic Diseases Nutritional and Metabolic Diseases Sedentary Behavior

Age range

18 year–55 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Research Institute for Sport and Exercise Sciences (RISES), Liverpool John Moores University

Liverpool, L3 3AF, United Kingdom

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Green Tea

Dietary Supplement

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 tea

Dietary Supplement

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.

Primary outcomes

  1. 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.

Secondary outcomes

  1. 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.

Sponsors and collaborators

Lead sponsor

Liverpool John Moores University

Other

Collaborators

  • Unilever R&D

Registry information

Official study title

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

Important dates

Study start
2016
Primary completion
2017
Study completion
2017
First posted
May 19, 2016
Registry last updated
Aug 24, 2017

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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