Effect of Black Tea on Vascular Function

Not Applicable

Completed

Conditions: Vascular Function

Interventions: Other: Black tea extract
Other: Positive control
Other: Placebo

Registration Number: NCT01945970

Lead Sponsor: Unilever R&D

Brief Summary: 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: 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.

Recruitment & Eligibility

Status: COMPLETED

Sex: Male

Target Recruitment: 30

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).

Exclusion Criteria

Not provided

Study & Design

Study Type: INTERVENTIONAL

Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Black tea extract	Black tea extract	Spray dried aqueous extract of a representative batch of black tea
Positive control	Positive control	Spray dried aqueous extract of a batch of tea extract that has shown to improve FMD previously
Placebo	Placebo	Food grade colouring, artificial tea flavour and an amount of caffeine matched to the caffeine in the Black tea extract

Primary Outcome Measures

Name	Time	Method
Flow Mediated Dilation, Acute-upon-chronic, Black Tea	From before consumption on day 1 to 2 hours post consumption on day 8.	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).

Secondary Outcome Measures

Name	Time	Method
Flow Mediated Dilation, Acute, Black Tea	From before consumption on day 1 to 2 hours post consumption on day 1	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).
Flow Mediated Dilation, Chronic, Black Tea	From before consumption day 1 to before consumption day 8.	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).
Flow Mediated Dilation, Acute-upon-chronic, Positive Control	From before consumption on day 1 to 2 hours post consumption on day 8	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).
Flow Mediated Dilation, Acute, Positive Control	From before consumption on day 1 to 2 hours post consumption on day 1	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).
Flow Mediated Dilation, Chronic, Positive Control	From before consumption on day 1 to before consumption day 8	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).