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Study Title and Description

The effect of caffeine, green tea and tyrosine on thermogenesis and energy intake.



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 caffeine, green tea and tyrosine on thermogenesis and energy intake.
Author A Belza,S Toubro,A Astrup,
Country
Year 2009
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 objective of this study was to investigate the effect of 50 mg caffeine (as well as tyrosine and green tea extract) compared to placebo control on thermogenesis, subjective appetite sensations, and ad libitum energy intake in a group of 12 normal weight men in a four-way cross-over, randomized, double-blinded study. As part of this study, hemodynamics (and other non-cardiovascular endpoints) were measured.
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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: Twelve healthy, normal weight men age 23.7 ± 2.6 years. They were non-smokers, non-athletic, were non-users of dietary supplements, and were low-to-moderate coffee consumers. They followed a normal Danish diet with the rare use of hot spices, avoiding the extreme intake of caffeine containing beverages. Experimental design: According to the authors, the study was a four-way crossover, randomized, placebo-controlled, double-blind study. Treatments were separated by a >3-day washout period. Subjects received tablets containing either 500 mg green tea extracts (containing 125 catechins), 400 mg tyrosine, 50 mg anhydrous caffeine, or placebo. Measurements: On each treatment day, subjects arrived at 0800 hours. Various body-related measurements were taken. At 0900 hours, subjects ingested one of the treatment compounds along with 175 mL tap water. Blood pressure and heart rate were taken at 0830, 0930, 1030, 1130, 1230, and 1300 hours. Statistical Analysis: All results are given in mean and standard error (s.e.). The level of significance was set at < 0.05. Differences between supplements were tested by analysis of mixed linear models procedure as repeated measurement adjusted for baseline level, and with or without adjusting for other confounders.
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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 No information provided.
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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.) Subjects served as their own control group. The placebo tablets contained microcrystalline cellulose.
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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) Differences between supplements were tested by analysis of mixed linear models procedure as repeated measurement adjusted for baseline level, and with or without adjusting for other confounders.
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What conflicts of interest were reported? No conflicts were reported.
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Refid 17882140
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What were the sources of funding? The study was supported by a grant from Science, Toxicology and Technology, San Francisco, CA, USA.
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Results & Comparisons

No Results found.