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Study Title and Description

Black tea consumption reduces total and LDL cholesterol in mildly hypercholesterolemic adults.



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 Black tea consumption reduces total and LDL cholesterol in mildly hypercholesterolemic adults.
Author MJ Davies,JT Judd,DJ Baer,BA Clevidence,DR Paul,AJ Edwards,SA Wiseman,RA Muesing,SC Chen,
Country
Year 2003
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 examine the effects of black tea ingestion on blood lipid profiles and markers of oxidative stress and antioxidant status in a controlled dietary setting with mildly hypercholesterolemic volunteers.
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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 Men and women were selected based on the following criteria: mildly elevated total cholesterol, 35 y-of-age or older, 90–140% of ideal body weight, no major health problems such as diabetes, heart disease, stroke, or cancer and not taking prescription medications that could interfere with lipid metabolism. Women had to be postmenopausal (last menses at least 1 y earlier) and not undergoing hormone replacement therapy. Volunteers had to be willing to consume all foods and beverages supplied by the study. Study design Volunteers were recruited to participate in a randomized double-blind crossover study of black tea (T) compared with a placebo having no added caffeine (P). To assess caffeine effects, a third period was added post hoc in which all subjects received the placebo with caffeine added (PC) at a concentration equivalent to that in T. Volunteers for the third study period were recruited from participants who completed periods 1 and 2 of the study. Beverages for T, P and PC treatments were prepared from dry powders similar to instant tea. Prior to the first treatment period volunteers were placed in a 2-wk run-in period. Additionally, treatments were separated by a 4-wk washout period. During these times, alcohol and tea consumption were not allowed. During all phases of the study (run-in, wash-out and treatment periods) volunteers ingested either one cup of caffeinated coffee or two caffeinated diet sodas daily thus establishing a consistent baseline level of caffeine intake and preventing possible caffeine withdrawal symptoms. Subjects eliminated other caffeine-containing foods and medications throughout the study. Controlled Diet During the three treatment periods, volunteers consumed the same background-controlled diet. All foods and beverages were prepared and supplied by the Human Studies Facility at the Beltsville Human Nutrition Research Center (Beltsville, MD). Food items were weighed, served in proportion to caloric requirements and color-coded according to the treatment beverage. Dietitians monitored food and treatment beverage selections at each meal. Blinding During the first two periods of the study, investigators, volunteers and kitchen staff were blinded to the T or P treatments. Because of the post hoc addition of a third treatment period, only the kitchen staff and volunteers were blinded to the PC treatment in the third study period. Volunteers consumed two servings of T or P (apple-flavored) with breakfast and the equivalent of three servings of T or P (lemon-flavored) with dinner for a total of five servings per day. All beverages were prepared with 180 mL of room temperature spring water per serving. Sample Collection Blood samples were drawn during the last week of the study on two different days and after an overnight fast (minimum 12 h). After the final blood collection, plasma, serum or LDL samples were analyzed with all samples for a subject included in the same analytical run. Plasma total cholesterol and HDL cholesterol were determined enzymatically using commercial kits (Sigma Chemical Company, St. Louis, MO) on an Abbott VP analyzer (Abbott Laboratories, Chicago, IL). LDL cholesterol was calculated by the Friedewald procedure. Statistics Statistical analyses were performed using SAS-PC version 8.2 (SAS Institute, Cary, NC). All variables from the start (baseline) and end of each treatment period were compared with a mixed model ANOVA that included fixed terms for treatment (i.e., T, P or PC) and period with a repeated term for volunteer. BMI and baseline value of the variable were included in the model as covariates to adjust for differences among the subjects for these parameters. Data are presented as least-square means +/- SEE [standard error of estimate] unless otherwise stated in the text. Values were considered statistical significant at P < 0.05.
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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) Serum cholesterol (TC, LDL, HDL)
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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 Plasma total cholesterol and HDL cholesterol were determined enzymatically using commercial kits (Sigma Chemical Company, St. Louis, MO) on an Abbott VP analyzer (Abbott Laboratories, Chicago, IL). LDL cholesterol was calculated by the Friedewald procedure.
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Caffeine (general) Caffeine (general)
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Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other? Tea
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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 received the same treatment as served as their own controls (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) None
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What conflicts of interest were reported? No information provided
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Refid 14519829
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What were the sources of funding? We thank Unilever Bestfoods NA for partial financial support and for preparation of the treatment beverages as well as for cooperation in the performance of the study.
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Results & Comparisons

No Results found.