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Study Title and Description

A Cup of Black Tea Does Not Modify Heart Rate Variability



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 A Cup of Black Tea Does Not Modify Heart Rate Variability
Author D. V. Syce
Country
Year 2015
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)? The purpose of the present study was to determine the effects of a cup of black tea on the HRV indices and on the other parameters of cardiac autonomic function in young South Indian subjects.
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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) Study Design and Participants This interventional study was conducted between August 2009 and March 2010 in the Department of Physiology, Pondicherry Institute of Medical Sciences (PIMS), Pondicherry, India. Fifty healthy young adult males from the technical staff of the institute volunteered. The subjects were between 18 and 25 years of age and drank fewer than four cups of coffee or tea or fewer than two 300mL bottles of caffeinated soft drinks per day. Individuals with systemic illnesses, sleep disturbances, neuromuscular disorders, psychiatric illness, peptic ulcer, or rhythm abnormalities of the heart were excluded. Smokers and those who consumed more than two units of alcohol per week were also excluded. Procedure The subjects were instructed to have a light breakfast (<250 calories), without coffee or tea, at 7 a.m. on the morning of the recordings. The recordings commenced at 9 a.m., and were performed in a quiet, dimly lit room, with an ambient temperature that varied between 37oC and 38oC over the duration of the study. After the subject had rested comfortably for 15 min on a couch, his right radial pulse rate was taken and blood pressure was recorded on the right arm using a sphygmomanometer (Diamond Company, India). After a further 10 min of supine rest, a lead II ECG was recorded for 5 min under standardized conditions using a computerized ambulatory electrocardiograph system (NIVIQURE, Bangalore, India). Subjects were instructed to close their eyes and to keep still during the recording. The obtained ECG signal, free of ectopics, was amplified, digitized, and stored in the computer for offline analysis. A sampling rate of 1,024Hz was used, and 256 beats were considered for analysis. These data were then analyzed by the fast Fourier Transformation (FFT) algorithm, and an R-R interval power spectrum was obtained. Preparation of Tea A Taj Mahal classic tea bag (Hindustan Unilever Ltd., Mumbai, India) was added to 200mL of boiling water in a cup with 10 g of sugar. The bag was kept in the cup for 3 min. The bag was then prodded six times and squeezed well along the sides of the cup while being removed. This was done in an attempt to obtain the maximum amount of caffeine per cup.7 Milk was avoided in order to prevent precipitation of compounds. The tea was then cooled to 55oC and the subject was instructed to consume it within 2min. Post-consumption testing Fifteen minutes after consumption, the same set of tests were repeated in the same order. Statistical Analysis The results obtained were analyzed using Student’s paired t -test for all variables, and are expressed below as mean +/- standard error of the mean (SEM) for HRV indices and as mean +/- standard deviation (SD ) for all other parameters.
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How many outcome-specific endpoints are evaluated? 3
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Blood pressure (SBP and DBP)
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List additional health endpoints (separately). 2 Heart rate
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List additional health endpoints (separately).3 Heart rate variability
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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? NCT
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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
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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.) Each study participant served as his 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) None
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What conflicts of interest were reported? No competing financial interests exist
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Refid 10466
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What were the sources of funding? No information provided
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Results & Comparisons

No Results found.