Effect of Black Tea on Vascular Function

Study Overview
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Brief Summary
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Epidemiological studies indicate that regular consumption of three cups of black tea per day reduces the risk of stroke or myocardial infarction. In a number of previous nutrition intervention studies tea has been shown to improve vascular function as assessed by Flow Mediated Dilation (FMD).

Detailed Description
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The current study tests a specific Black tea extract against a placebo in population that has previously show to be sensitive to the effect of black tea on Flow Mediated dilation. A tea extract that has previously been shown to improve FMD is included as the positive control.

Official Title
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Randomized Double Blind Placebo Controlled Crossover Study to Assess the Effect of Black Tea on Flow-Mediated Dilation in Healthy, Non-tea Drinking Males

Conditions
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Vascular Function

Intervention / Treatment
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* Other: Black tea extract
* Other: Positive control
* Other: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Apparently healthy male volunteers with no history of cardiovascular disease Having body mass index (BMI) of between 18.0 and 30.0 kg/m2 (inclusive) Non-smokers (> 2 years) Non-tea drinkers (less or equal 1 cup/week) Limited alcohol intake (less or equal 21 units/week) Systolic blood pressure less or equal 160 mmHg and/or diastolic blood pressure less or equal 100 mmHg at screening Brachial artery can be imaged using ultrasound and at screening FMD value is within the expected range as judged by the PI Judged to be in good health on the basis of medical history, physical examination and routine laboratory tests (total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, glucose, highly sensitive C-reactive protein).

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Black tea extract<br>Spray dried aqueous extract of a representative batch of black tea | Other: Black tea extract<br>* Black tea extract<br>|
| Active Comparator: Positive control<br>Spray dried aqueous extract of a batch of tea extract that has shown to improve FMD previously | Other: Positive control<br>* Positive control<br>|
| Placebo Comparator: Placebo<br>Food grade colouring, artificial tea flavour and an amount of caffeine matched to the caffeine in the Black tea extract | Other: Placebo<br>* Placebo<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Flow Mediated Dilation, Acute-upon-chronic, Black Tea | Flow mediated dilation (FMD) measurement included the following steps: 1 minute base scan to measure the baseline diameter of artery (Resting stage) 5 minutes of forearm occlusion at 300±30 mmHg (cuff occlusion stage), just below the elbow 2-5 cm from antecubital crease) 4 minutes FMD scan, which started immediately after release of occlusion (reactive hyperaemia stage) When the artery had returned to baseline a second 1 minute scan was taken 25 µg sublingual glyceryl trinitrate (GTN) was given to the subject 5 minutes GTN scan to assess the endothelium-independent dilation FMD and response to GTN was calculated as maximal percent increase in diameter above baseline (mean value of measures obtained during 1 minute before cuff inflation). | From before consumption on day 1 to 2 hours post consumption on day 8. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Flow Mediated Dilation, Acute, Black Tea | Flow mediated dilation (FMD) measurement included the following steps: 1 minute base scan to measure the baseline diameter of artery (Resting stage) 5 minutes of forearm occlusion at 300±30 mmHg (cuff occlusion stage), just below the elbow 2-5 cm from antecubital crease) 4 minutes FMD scan, which started immediately after release of occlusion (reactive hyperaemia stage) When the artery had returned to baseline a second 1 minute scan was taken 25 µg sublingual glyceryl trinitrate (GTN) was given to the subject 5 minutes GTN scan to assess the endothelium-independent dilation FMD and response to GTN was calculated as maximal percent increase in diameter above baseline (mean value of measures obtained during 1 minute before cuff inflation). | From before consumption on day 1 to 2 hours post consumption on day 1 | 
| Flow Mediated Dilation, Chronic, Black Tea | Flow mediated dilation (FMD) measurement included the following steps: 1 minute base scan to measure the baseline diameter of artery (Resting stage) 5 minutes of forearm occlusion at 300±30 mmHg (cuff occlusion stage), just below the elbow 2-5 cm from antecubital crease) 4 minutes FMD scan, which started immediately after release of occlusion (reactive hyperaemia stage) When the artery had returned to baseline a second 1 minute scan was taken 25 µg sublingual glyceryl trinitrate (GTN) was given to the subject 5 minutes GTN scan to assess the endothelium-independent dilation FMD and response to GTN was calculated as maximal percent increase in diameter above baseline (mean value of measures obtained during 1 minute before cuff inflation). | From before consumption day 1 to before consumption day 8. | 
| Flow Mediated Dilation, Acute-upon-chronic, Positive Control | Flow mediated dilation (FMD) measurement included the following steps: 1 minute base scan to measure the baseline diameter of artery (Resting stage) 5 minutes of forearm occlusion at 300±30 mmHg (cuff occlusion stage), just below the elbow 2-5 cm from antecubital crease) 4 minutes FMD scan, which started immediately after release of occlusion (reactive hyperaemia stage) When the artery had returned to baseline a second 1 minute scan was taken 25 µg sublingual glyceryl trinitrate (GTN) was given to the subject 5 minutes GTN scan to assess the endothelium-independent dilation FMD and response to GTN was calculated as maximal percent increase in diameter above baseline (mean value of measures obtained during 1 minute before cuff inflation). | From before consumption on day 1 to 2 hours post consumption on day 8 | 
| Flow Mediated Dilation, Acute, Positive Control | Flow mediated dilation (FMD) measurement included the following steps: 1 minute base scan to measure the baseline diameter of artery (Resting stage) 5 minutes of forearm occlusion at 300±30 mmHg (cuff occlusion stage), just below the elbow 2-5 cm from antecubital crease) 4 minutes FMD scan, which started immediately after release of occlusion (reactive hyperaemia stage) When the artery had returned to baseline a second 1 minute scan was taken 25 µg sublingual glyceryl trinitrate (GTN) was given to the subject 5 minutes GTN scan to assess the endothelium-independent dilation FMD and response to GTN was calculated as maximal percent increase in diameter above baseline (mean value of measures obtained during 1 minute before cuff inflation). | From before consumption on day 1 to 2 hours post consumption on day 1 | 
| Flow Mediated Dilation, Chronic, Positive Control | Flow mediated dilation (FMD) measurement included the following steps: 1 minute base scan to measure the baseline diameter of artery (Resting stage) 5 minutes of forearm occlusion at 300±30 mmHg (cuff occlusion stage), just below the elbow 2-5 cm from antecubital crease) 4 minutes FMD scan, which started immediately after release of occlusion (reactive hyperaemia stage) When the artery had returned to baseline a second 1 minute scan was taken 25 µg sublingual glyceryl trinitrate (GTN) was given to the subject 5 minutes GTN scan to assess the endothelium-independent dilation FMD and response to GTN was calculated as maximal percent increase in diameter above baseline (mean value of measures obtained during 1 minute before cuff inflation). | From before consumption on day 1 to before consumption day 8 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Vascular function, Flow mediated dilation, Tea