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Study Title and Description

The effect of black tea and caffeine on regional cerebral blood flow measured with arterial spin labeling.



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 The effect of black tea and caffeine on regional cerebral blood flow measured with arterial spin labeling.
Author R Vidyasagar,A Greyling,R Draijer,DR Corfield,LM Parkes,
Country
Year 2013
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)? Black tea consumption has been shown to improve peripheral vascular function. Its effect on brain vasculature is unknown, though tea contains small amounts of caffeine, a psychoactive substance known to influence cerebral blood flow (CBF). We investigated the effects on CBF due to the intake of tea components in 20 healthy men in a double-blinded, randomized, placebo-controlled study.
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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) The study was a double-blinded, placebo-controlled randomized full crossover design with four treatments: (1) caffeine intervention (184mg of caffeine) (2) tea intervention (2,820mg of black tea solids, 32% polyphenols, containing 184mg of caffeine) (3) decaffeinated black tea (2,820mg of black tea solids, 28% polyphenols) and (4) placebo (microcrystalline cellulose). The four visits were separated by a minimum period of 1 week to allow for effective washout of the test products from the subjects’ system. Order of administration of interventions was randomized for each subjects’ visit using a Williams design. The MRI measurements were performed using a 3-tesla Trio whole-body scanner (Siemens, Erlangen, Germany). An 8-channel RF coil was used for signal collection and the body coil for signal transmission. Subjects arrived at the test site in the morning in a fasted state and were given a standard cereal bar (consisting of sugar, oats, honey and nuts without any dairy or polyphenols) before the first scan session. After the scan session, subjects were given the six capsules containing a treatment. They were then scanned again 1.5 hours after the capsules were consumed (when tea catechins reach peak plasma level17 and when caffeine plasma level is also high18), with the same scan protocol. In total, each subject had eight scan sessions, two sessions per treatment.
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How many outcome-specific endpoints are evaluated? 1
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Cerebral blood flow and cerebrovascular reactivity.
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List additional health endpoints (separately). 2
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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
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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.) 184 mg caffeine or placebo.
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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) The study was a double-blinded, placebo-controlled randomized full crossover design with four treatments: (1) caffeine intervention (184mg of caffeine) (2) tea intervention (2,820mg of black tea solids, 32% polyphenols, containing 184mg of caffeine) (3) decaffeinated black tea (2,820mg of black tea solids, 28% polyphenols) and (4) placebo (microcrystalline cellulose). The four visits were separated by a minimum period of 1 week to allow for effective washout of the test products from the subjects’ system. Order of administration of interventions was randomized for each subjects’ visit using a Williams design. The MRI measurements were performed using a 3-tesla Trio whole-body scanner (Siemens, Erlangen, Germany). An 8-channel RF coil was used for signal collection and the body coil for signal transmission. Subjects arrived at the test site in the morning in a fasted state and were given a standard cereal bar (consisting of sugar, oats, honey and nuts without any dairy or polyphenols) before the first scan session. After the scan session, subjects were given the six capsules containing a treatment. They were then scanned again 1.5 hours after the capsules were consumed (when tea catechins reach peak plasma level17 and when caffeine plasma level is also high18), with the same scan protocol. In total, each subject had eight scan sessions, two sessions per treatment.
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What conflicts of interest were reported? Not discussed.
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Refid 23486295
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What were the sources of funding? AG & RD are employed by Unilever R&D Vlaardingen. Unilever produces foods of which some are marketed to fit in a healthy diet and lifestyle.
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