Tea Components, Mental Stress and Blood Pressure

A Study to Determine the Acute Effects of a Tea Component on Blood Pressure and Mental Stress Challenge

Assess the effects of adding theanine to a caffeinated beverage on changes in blood pressure during acute mental stress.

Study Overview

• Status: Completed
• Conditions: Healthy
• Intervention / Treatment: Other: Combination of caffeine and theanine; Other: Caffeine

Detailed Description

Caffeine and (mental) stress can increase blood pressure. In a typical everyday and/or work environment they commonly coincide. Tea has the reputation of being a relaxing drink. L-theanine is an amino acid found almost exclusively in tea. In a previous study it was shown that caffeine increased blood pressure, while theanine antagonised these effects. In the current study the effect of theanine to a placebo on blood pressure are directly compared.

• Study Type: Interventional
• Enrollment (Actual): 56
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • London, United Kingdom
    • University College London

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 45 years (ADULT)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Apparently healthy males and females
• Women taking the contraceptive pill
• 18-45 years of age
• BMI 20-30 kg/m2
• Normal or corrected vision
• Low caffeine consumers (<100mg/day)
• Non smokers and having been a non-smoker for > 6 months
• Fluent English
• Normotensive (>90/60 <140/90 mmHg)

Exclusion Criteria:

• Significant current or medical history of cardiovascular disease
• Low or high STAI trait score in the opinion of the PI
• Known sensitivity to caffeine or theanine
• Colour blindness
• Alcohol consumption above 14/21 units female/male resp. per week
• Weight loss diet > 10% of bodyweight in the previous year
• Anyone with a dependency on PI or staff of Department of Epidemiology and Public Health or being an employee of Unilever
• Reported participation in another biomedical study < 3 months before screening

Study Plan

How is the study designed?

Design Details

• Primary Purpose: TREATMENT
• Allocation: RANDOMIZED
• Interventional Model: CROSSOVER
• Masking: QUADRUPLE

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
EXPERIMENTAL: Combination of caffeine and theanine; 250 mg caffeine + 200 mg theanine	Other: Combination of caffeine and theanine; Beverage containing caffeine and theanine
PLACEBO_COMPARATOR: Caffeine; 250 mg caffeine	Other: Caffeine; Beverage containing caffeine

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Systolic blood pressure during stress	Systolic blood pressure during acute mental stress	Between 30-45 minutes after test product intake

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Diastolic blood pressure during stress	Diastolic blood pressure during acute mental stress	Between 30-45 minutes after test product intake
Systolic blood pressure after stress	Systolic blood pressure immediately after acute mental stress	Between 45-60 minutes after test product intake
Diastolic blood pressure after stress	Diastolic blood pressure immediately after acute mental stress	Between 45-60 minutes after test product intake
STAI before and immediately after stress	Self-reported mental state: State-Trait Anxiety Inventory	-15 and 45 relative to test product intake
UWIST before and immediately after stress	Self-reported mental state: University Of Wales Institute of Science and Technology mood adjective questionnaire	-10, 45 minutes relative to test product intake

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cortisol in saliva before and immediately after stress	Concentration of cortisol in saliva	-5, 45 min relative to test product intake
Heart rate during stress	Heart rate during acute mental stress	Between 30-45 minutes after test product intake
Heart rate after stress	Heart rate immediately after acute mental stress	Between 45-60 minutes after test product intake
Heart rate variability during stress	Heart rate variability during acute mental stress	Between 30-45 minutes after test product intake
Heart rate variability after stress	Heart rate variability immediately after acute mental stress	Between 45-60 minutes after test product intake
Performance STROOP	Task performance on STROOP task	Between 30-45 minutes after test product intake
Performance mirror tracing	Task performance on mirror tracing task	Between 30-45 minutes after test product intake
Systolic blood pressure, free living phase	Ambulatory systolic blood pressure during free living phase	Between 80-270 minutes after test product intake
Diastolic blood pressure, free living phase	Ambulatory diastolic blood pressure during free living phase	Between 80-270 minutes after test product intake
Cortisol, free living phase	Concentration of cortisol in saliva during free living phase	140, 200 and 260 minutes after test product intake
STAI, free living phase	Self-reported mental state: State-Trait Anxiety Inventory during free living phase	140, 200 and 260 minutes after test product intake
UWIST, free living phase	Self-reported mental state: University Of Wales Institute of Science and Technology) mood adjective questionnaire during free living phase	140, 200 and 260 minutes after test product intake
Pulse pressure during stress	Mean pulse pressure during mental stress	Between 30-45 minutes after test product intake
Pulse pressure after stress	Mean pulse pressure after acute mental stress	Between 45-60 minutes after test product intake
Mental wellbeing	Mental well being as assessed by on line survey an each evening during the 7 day period the accelerometer is worn.	7 consecutive days prior to the lab sessions
Physical activity	Habitual patterns in physical activity as measured by accelerometer	7 consecutive days prior to the lab sessions
STAI screening	State-Trait Anxiety Inventory (STAI) - Trait version, covariate	Screening
CES-D	Center for Epidemiologic Studies Depression scale, covariate	Screening
CISS	CISS coping scale, covariate	Screening
loneliness	UCLA loneliness scale, covariate	Screening
Perceived stress	Perceived Stress Scale, covariate	Screening

Collaborators and Investigators

• Sponsor: Unilever R&D
• Collaborators: University College, London
• Investigators: Principal Investigator: Mark Hamer, Dr, UCL, Epidemiology & Public Health, London

Study record dates

Study Major Dates

• Study Start: March 1, 2015
• Primary Completion (ACTUAL): October 1, 2015
• Study Completion (ACTUAL): November 1, 2015

Study Registration Dates

• First Submitted: November 12, 2014
• First Submitted That Met QC Criteria: November 19, 2014
• First Posted (ESTIMATE): November 24, 2014

Study Record Updates

• Last Update Posted (ESTIMATE): December 4, 2015
• Last Update Submitted That Met QC Criteria: December 3, 2015
• Last Verified: December 1, 2015

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Behavioral Symptoms; Stress, Psychological; Physiological Effects of Drugs; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Enzyme Inhibitors; Purinergic Antagonists; Purinergic Agents; Phosphodiesterase Inhibitors; Purinergic P1 Receptor Antagonists; Central Nervous System Stimulants; Caffeine
• Other Study ID Numbers: REF-BEV-1803