Flow Mediated Dilation in Response to Black Tea (T)

Flow Mediated Dilation in Response to Consumption of Black Tea Versus Artificial Tea, in Non-tea Drinking Hypertensive Subjects.

Research indicate that people who regularly drink tea have a reduced risk of stroke or heart disease. In a number of studies in which people that normally do not drink showed that their blood vessels function improved when the drunk tea. The current study tests whether a specific black tea improves vessel function in non-tea drinking hypertensive subjects.

Study Overview

• Status: Completed
• Conditions: Vascular Function
• Intervention / Treatment: Other: Tea; Other: Placebo

Detailed Description

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 in various populations. The current confirmatory study tests a specific black tea against a placebo in a population of in non-tea drinking hypertensive subjects.

• Study Type: Interventional
• Enrollment (Actual): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • London, United Kingdom, SE1 7EH
    • Dept Clinical Pharmacology/CRF, St Thomas Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Males and post menopausal (> 1 year) females, not on hormone replacement therapy
• Aged >18 and < 65 years
• Body mass index (BMI) of >=18.0 and =<35.0 kg/m2

• Hypertension as previously diagnosed by primary care or hospital physician.

  • If untreated, office BP between 140/90 mmHg and 160/100 mmHg on screening
  • If treated, a controlled blood pressure (<160/100) on stable medication for at least 4 weeks

Exclusion Criteria:

• Tea drinkers: having typically consumed > 1 cup of black tea per week.
• Current smoker or has stopped smoking less than 6 months before start of study
• Self reported alcohol intake of >21 units/week
• Established cardiovascular disease other than hypertension
• Clinically significant arrhythmia
• Diabetes mellitus
• Chronic Kidney Disease > stage 2
• 10-year cardiovascular risk equivalent to 20% or greater using the QRisk2 calculator
• Abnormality of laboratory blood tests considered clinically significant
• Any other significant intercurrent condition/disease

Study Plan

How is the study designed?

Design Details

• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Placebo	Other: Placebo; Placebo: tea flavour, colouring and sugar
Experimental: Tea; Black tea	Other: Tea; Single dose of black tea infusion containing approximately 400 mg flavonoids (expressed as gallic acid equivalents) with added sugar.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Flow Mediated Dilation	Flow mediated dilation (FMD) of the brachial artery was measured using vascular ultra sound and automated edge detection software: 1 minute baseline scan to measure the baseline diameter of artery; 5 minutes of forearm occlusion at 250±30 mmHg, below the elbow (2-5 cm from antecubital crease); 4 minutes FMD scan, which started immediately after release of occlusion Percentage FMD was calculated as the maximum increase in diameter after cuff release relative to the baseline diameter	Before and 2 hours after test product intake

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Endothelium-independent Vasodilation	Endothelium-independent dilation after glyceryl trinitrate defined as maximal percent increase in diameter	2.5 hours after test product intake
Systolic Blood Pressure Supine	Systolic blood pressure measured while lying down	Before and 110 minutes after test product intake
Diastolic Blood Pressure Supine	Diastolic blood pressure measured while lying down	Before and 110 minutes after test product intake
Systolic Blood Pressure Sitting	Systolic blood pressure measured while sitting	Before and 90 minutes after test product intake
Diastolic Blood Pressure Sitting	Diastolic blood pressure measured while sitting	Before and 90 minutes after test product intake

Collaborators and Investigators

• Sponsor: Unilever R&D
• Collaborators: King's College London
• Investigators: Principal Investigator: Phillip Chowienczyk, Professor, Dept Clinical Pharmacology/CRF, St Thomas Hospital, London UK

Study record dates

Study Major Dates

• Study Start: October 1, 2014
• Primary Completion (Actual): October 1, 2015
• Study Completion (Actual): October 1, 2015

Study Registration Dates

• First Submitted: October 21, 2014
• First Submitted That Met QC Criteria: October 21, 2014
• First Posted (Estimate): October 23, 2014

Study Record Updates

• Last Update Posted (Actual): February 15, 2017
• Last Update Submitted That Met QC Criteria: December 21, 2016
• Last Verified: December 1, 2016

More Information

Terms related to this study

• Keywords: blood pressure; tea; Flow mediated dilation
• Additional Relevant MeSH Terms: Pathological Conditions, Anatomical; Dilatation, Pathologic
• Other Study ID Numbers: REF-BEV-1376

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No