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Study Title and Description

Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together.



Key Questions Addressed
1 For [population], is caffeine intake above [exposure dose], compared to intakes [exposure dose] or less, associated with adverse effects on cardiovascular outcomes?
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Primary Publication Information
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TitleData
Title Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together.
Author PJ Rogers,JE Smith,SV Heatherley,CW Pleydell-Pearce,
Country
Year 2008
Numbers

Secondary Publication Information
There are currently no secondary publications defined for this study.


Extraction Form: Cardiovascular Design
Design Details
Question... Follow Up Answer Follow-up Answer
What outcome is being evaluated in this paper? Cardiovascular
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What is the objective of the study (as reported by the authors)? Per the authors, the objective of the study was to evaluate the subjective, behavioral and blood pressure effects of theanine and caffeine administered alone and together, in doses relevant to the daily tea consumption of regular tea drinkers.
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Provide a general description of the methods as reported by the authors. Information should be extracted based on relevance to the SR (i.e., caffeine related methods) Subjects: According to the authors’ description, forty-eight healthy, young adults (age 18-28 years) took part in the study. They were students recruited via print and email advertisements. The study was described as an investigation into the effects of tea on mood. They read an information sheet which outlined the study and stated that they would be asked to consume constituents of tea (caffeine and theanine were not mentioned explicitly). STUDY DESIGN: The study employed a between-subjects design; participants received either caffeine with a theanine placebo, theanine with a caffeine placebo, caffeine together with theanine or caffeine placebo with theanine placebo. Twelve of each of these four treatments were prepared and allocated to participants randomly (without replacement). Treatments were administered double blind. Each participant received a capsule and a 200-ml drink. The capsule contained 250 mg of caffeine or cornflour (caffeine placebo). The drinks contained 200 mg of theanine or no theanine (theanine placebo) and were kept at room temperature and served in a clear glass. They had a peach flavor, but contained no tea constituents, other than theanine as necessary. The placebo- and theanine-containing drinks were not perceptibly different in appearance or taste. Measure of mood, alertness and physical symptoms questionnaire (MAPS): This questionnaire consisted of seven unipolar and four bipolar ten-point scales (0–9) adapted from a similar questionnaire used in previous research on caffeine (e.g. Rogers et al. 2005). ‘Headache’, ‘heart pounding’, ‘jittery/shaky’, ‘light-headed/feeling faint/dizzy’, ‘hands trembling’, ‘scared’, and ‘feeling hot/sweating (not due to heat)’ were rated on unipolar scales labelled ‘I don’t have this feeling at all’ (left-hand end=0) and ‘I have this feeling very strongly’ (right-hand end=9). The bipolar scales were relaxed (labelled ‘anxious/tense/nervous/on edge’=0 and ‘relaxed/calm’=9), clearheaded (labelled ‘muzzy/dazed’=0 and ‘clearheaded’=9), happy (labelled ‘sad/gloomy/miserable’=0 and ‘happy/cheerful/light-hearted’=9) and alert (labelled ‘drowsy, sluggish, tired, fatigued’=0 and ‘alert/energetic/lively’=9). Instructions asked participants to rate ‘how you feel RIGHT NOW’. Mood, alertness and physical symptoms questionnaire (MAPS) This paper questionnaire consisted of seven unipolar and four bipolar ten-point scales (0–9) adapted from a similar questionnaire used in previous research on caffeine (e.g. Rogers et al. 2005). ‘Headache’, ‘heart pounding’, ‘jittery/shaky’, ‘light-headed/feeling faint/dizzy’, ‘hands trembling’, ‘scared’, and ‘feeling hot/sweating (not due to heat)’ were rated on unipolar scales labelled ‘I don’t have this feeling at all’ (left-hand end=0) and ‘I have this feeling very strongly’ (right-hand end=9). The bipolar scales were relaxed (labelled ‘anxious/tense/nervous/on edge’=0 and ‘relaxed/calm’=9), clearheaded (labelled ‘muzzy/dazed’=0 and ‘clearheaded’=9), happy (labelled ‘sad/gloomy/miserable’=0 and ‘happy/cheerful/light-hearted’=9) and alert (labelled ‘drowsy, sluggish, tired, fatigued’=0 and ‘alert/energetic/lively’=9). Participants were asked to rate ‘how you feel RIGHT NOW’. Mood, alertness and physical symptoms questionnaire (MAPS) This paper questionnaire consisted of seven unipolar and four bipolar ten-point scales (0–9) adapted from a similar questionnaire used in previous research on caffeine (e.g. Rogers et al. 2005). ‘Headache’, ‘heart pounding’, ‘jittery/shaky’, ‘light-headed/feeling faint/dizzy’, ‘hands trembling’, ‘scared’, and ‘feeling hot/sweating (not due to heat)’ were rated on unipolar scales labelled ‘I don’t have this feeling at all’ (left-hand end=0) and ‘I have this feeling very strongly’ (right-hand end=9). The bipolar scales were relaxed (labelled ‘anxious/tense/nervous/on edge’=0 and ‘relaxed/calm’=9), clearheaded (labelled ‘muzzy/dazed’=0 and ‘clearheaded’=9), happy (labelled ‘sad/gloomy/miserable’=0 and ‘happy/cheerful/light-hearted’=9) and alert (labelled ‘drowsy, sluggish, tired, fatigued’=0 and ‘alert/energetic/lively’=9). Instructions asked participants to rate ‘how you feel RIGHT NOW’. Blood pressure and heart rate: Systolic and diastolic blood pressure and heart rate were measured using the Omron 711 Intellisense automatic inflation monitor. The participants rested their left arm on a table, and the cuff was applied level with the chest. Participants had been seated for at least 5 min before the measurements were taken. After completing the tests, participants were asked about the purpose of the study. Afterwards, they were told the full purpose of the study and were asked to guess which treatments they had received. Statistical Analysis: Post-treatment data for MAPS and blood pressure were analyzed using analysis of covariance with caffeine (caffeine/placebo) and theanine (theanine/placebo) and computer-task order (visual probe task first/facial expression recognition task first) as between-subjects factors and pre-treatment (baseline) data for the measure as the covariate.
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How many outcome-specific endpoints are evaluated? 2
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Heart rate
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List additional health endpoints (separately). 2 Blood pressure (systolic and diastolic)
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List additional health endpoints (separately).3
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List additional health endpoints (separately).4
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List additional health endpoints (separately).5
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List additional health endpoints (separately).6
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Clinical, physiological, other Physiological
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What is the study design? Controlled Trial
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Randomized or Non-Randomized? RCT
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What were the diagnostics or methods used to measure the outcome? Objective
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Optional: Name of Method or short description Systolic and diastolic blood pressure and heart rate were measured using the Omron 711 Intellisense automatic inflation monitor.
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Caffeine (general) Caffeine (general)
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Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other?
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Measured or self reported? Measured
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Children, adolescents, adults, or pregnant included? Adults
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What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.) Placebo containing cornflour. Each person served as their own control.
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What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models.  Copy from methods) Post-treatment data for MAPS and blood pressure were analyzed using analysis of covariance with caffeine (caffeine/placebo) and theanine (theanine/placebo) and computer-task order (visual probe task first/facial expression recognition task first) as between-subjects factors and pre-treatment (baseline) data for the measure as the covariate.
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What conflicts of interest were reported? No conflicts were reported.
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Refid 17891480
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What were the sources of funding? The authors thank Unilever plc for donation of the theanine-containing drinks used in this study and Mars UK for permission to cite the unpublished results on effects of theanine on blood pressure from a previous study. The unpublished research on perceived effects of coffee and tea (Bristol Dietary Caffeine and Health Study) was supported by BBSRC.
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