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Study Title and Description

Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses.



Key Questions Addressed
1 For [population], is caffeine intake above [exposure dose], compared to intakes [exposure dose] or less, associated with adverse effects on behavior*?
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Primary Publication Information
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TitleData
Title Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses.
Author A Yoto,M Motoki,S Murao,H Yokogoshi,
Country
Year 2012
Numbers

Secondary Publication Information
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Extraction Form: Behavior - Design Details - INCLUDED Studies
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Design Details
Question... Follow Up Answer Follow-up Answer
Refid 23107346
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What outcome is being evaluated in this paper? Behavior
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What is the objective of the study (as reported by the authors)? In this study, we investigated the effects of L-theanine or caffeine on mental task performance and the change in blood pressure caused by mental tasks as psychological stress and by the cold pressor test as physical stress.
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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) Participants Sixteen healthy volunteers (students, eight men, eight women; ages, 22.8±2.1 years) participated in the experiment individually at similar times of the day at an interval of 7 days. The data from two women were excluded from the analyses because they were absent on at least 2 experiment days owing to temporary illness. All participants were requested to avoid eating or drinking, except for water, from 3 h before the start of each trial. Treatment A cross-over, randomized, placebo-controlled design was used in this study. In total, three separate trials were performed, in which the participants orally took either Ltheanine (200 mg, Taiyo Kagaku Co., Tokyo, Japan) + placebo, caffeine (100 mg, Shiratori Pharmaceutical Co., Chiba, Japan) + placebo, or placebo only on each day. Dextrin (Nisshin Pharma Inc., Tokyo, Japan) was used as the placebo. All sample capsules were taken with 250 mL warm water at about 25°C. Treatments were allocated using a Latin square design such that the order of treatments was counterbalanced across participants. To allow a peak of both L-theanine and caffeine appears during the stress load period, sample treatment was decided to be taken at 36 min before the end of the mental tasks session (DT and AT as defined below), followed by subjective assessment which was performed from 38 min to 43 min, physiological measurement from 44 min to 45 min, and physical stress task session (CPT) from 45 min to 49 min after the sample treatment. Stress load task After each sample was taken, an auditory oddball target detection task (DT) lasting for 5 min each and an arithmetic mental task (AT) lasting for 10 min each were both imposed twice as the psychological stress load. A cold pressor test (CPT) was taken to establish physical acute stress [20]. Subjective assessment The Profile of Mood States (POMS) and the visual analogue scales (VAS) for subjective ratings on mood state were also completed before the intake as a basic control and after all of the mental tasks were finished. The short version of POMS was used to assess distinct affective mood states. POMS is a popular tool that is widely used among psychologists and scientists in many fields. Six identifiable mood or affective states can be measured and were used for analysis in this study: Tension-Anxiety (T-A), Depression-Dejection (D), Anger-Hostility (A-H), Vigor-Activity (V), Fatigue Anger-Hostility (A-H), Vigor-Activity (V), Fatigue- Inertia (F), and Confusion-Bewilderment (C). VAS comprised five scales including feelings of fatigue, relaxation, arousal, pressure, and tension. At the end of each trial, the subjects used the scales to rate their painful feelings about accomplishing the CPT and their feelings of annoyance about DT and AT. Procedure Figure 1 shows the experimental procedure. Each participant was required to attend a total of 3 study days, which were conducted 7 days apart, to ensure a sufficient washout between conditions. Prior to the start of the experiment, all participants were given the opportunity to familiarize themselves with all of the stress load tasks. The experiments took place in a quiet room. The room temperature was 26.4±1.1°C, and the humidity was 51.5±6.8%. On each experiment day, each participant entered the room and rested for 15 min. During the resting time, a skin-surface temperature probe was attached, and POMS and VAS were completed. After the rest, a 1-min physiological measurement session to obtain baseline data took place, followed by sample treatment. After the oral administration, mental tasks were performed: DT (5 min), rest (2 min), AT (10 min), and rest (2 min); the cycle was then repeated. Then, POMS and VAS and another 1-min measurement were completed again to obtain data after the mental tasks. CPT for 1 min was then started. At the same time, measurement was recorded for 4 min (1 min for CPT, 3 min for RP after CPT). At last, VAS about feelings of DT, AT, and CPT was completed. Statistical analysis Data were analyzed using IBM SPSS Statistics version 19. Prior to the primary statistical analysis, separate, one-way, repeated measures ANOVAs of the baseline data were conducted to ascertain any chance baseline differences across study days prior to the treatments. Differences in POMS and VAS scores were analyzed using the nonparametric Friedman test to detect differences in treatments. The Wilcoxon signed rank test was further carried out to evaluate the changes among treatments.
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How many outcome-specific endpoints are evaluated? 5
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) anxiety-tension
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List additional health endpoints (separately). confusion-bewilderment
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List additional health endpoints (separately)
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Notes also measured Vigor-activity, arousal, and pressure
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Clinical
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Physiological
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Other
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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? Subjective
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Optional: Name of Method or short description Profile of Mood States and visual analogue scales
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Caffeine (general) Caffeine (general)
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Coffee
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Chocolate
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Energy drinks
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Gum
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Medicine/Supplement
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Soda
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Tea
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Measured Measured
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Self-report
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Children
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Adolescents
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Adults Adults
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Pregnant Women
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What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.) placebo (0 mg caffeine) vs 100 mg caffeine
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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) N/A
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Provide a general description of results (as reported by the authors). Figure 4 presents the significant results of POMS scores. T-A scores and A-H scores showed treatment effects over the two groups together (χ2=6.000, 6.048, P=0.050, 0.049), and L-theanine intake decreased T-A score below that in the placebo condition (P=0.004). No difference was obtained among treatments in each group or two groups together for VAS assessments.
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Did the authors perform a dose-response analysis (or trend/related analysis)? No
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What were the authors's observations re: trend analysis?
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What were the author's conclusions? [no specific conclusions from the author on the effects of caffeine on mood. conclusions focus on theanine's effects on blood pressure.
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What were the sources of funding? This work was supported in part by grants from the Collaboration of Regional Entities for the Advancement of Technological Excellence (CREATE), research funds provided by the Japan Society and Technology Agency (JST), and by a Grant-in-Aid for Scientific Research (B) provided by the Japan Society for the Promotion of Sciences (JSPS) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.
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What conflicts of interest were reported? The authors declare that they have no competing interests.
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Does the exposure (dose) need to be standardized to the SR? No
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Provide calculations/conversions for the exposure based on the decision tree in the guide (for all endpoints/exposure levels of interest).
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List all the endpoint(s) followed by the dose (mg) which will be used in comparison to Nawrot.  Characterize value as LOAEL/NOAEL, etc. if possible.  Tension-Anxiety - NOAEL = 100 mg caffeine Depression-Dejection - NOAEL = 100 mg caffeine Anger-Hostility - NOAEL = 100 mg caffeine Fatigue-Inertia (F) - NOAEL = 100 mg caffeine Confusion-Bewilderment (C) - NOAEL = 100 mg caffeine
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Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot. single dose no effect seen at levels below Nawrot.
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What is the importance of the study with respect to the adverseness of the outcome? Important
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