Insulin Resistance
Conditions
Keywords
tea, cardiovascular, vascular, metabolism, microcirculation, physical inactivity, polyphenols, conduit artery, endothelial function, cerebrovascular, insulin sensitivity
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.
Interventions
DIETARY_SUPPLEMENTGreen tea
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.
DIETARY_SUPPLEMENTPlacebo tea
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.
Sponsors
Unilever R&D
Liverpool John Moores University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
PREVENTION
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
MALE
Age
18 Years to 55 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| 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
| Measure | Time frame | Description |
|---|---|---|
| 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. |
Countries
United Kingdom
Outcome results
None listed