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Study Title and Description

Abstention from filtered coffee reduces the concentrations of plasma homocysteine and serum cholesterol--a randomized controlled trial.



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 Abstention from filtered coffee reduces the concentrations of plasma homocysteine and serum cholesterol--a randomized controlled trial.
Author B Christensen,A Mosdol,L Retterstol,S Landaas,DS Thelle,
Country
Year 2001
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)? A prospective intervention study was performed to assess the effects of coffee consumption on the concentrations of tHcy and total cholesterol by using doses and brewing methods common in southeastern Norway.
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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) Trial Design and Sample Size Calculation The study was organized as a prospective, unblinded controlled trial with the participants randomly assigned to 3 different treatment groups that were to consume for 6 consecutive weeks no coffee, 1–3 cups (approx. 175–525 mL) of coffee/d, or ≥4 cups (approx. 700 mL) of coffee/d. On the basis of the differences observed in the cross-sectional study, we estimated the expected difference in tHcy between the 2 extreme groups to be on the order of 1.5 umol/L. Given a statistical power of 0.9 (90% probability for detecting this difference if it is there) at a significance level of 0.05, each group would need 60 persons. Subjects and procedure The participants were recruited by an advertisement we placed in the largest newspaper in Oslo. Inclusion criteria were age 24–69 y, a history of daily consumption of coffee for ≥5 y, and no daily tobacco smoking for the past 6 mo. All participants were provided with oral and written information; on entering the trial, they completed a questionnaire relating to exclusion criteria. Exclusion criteria included clinically recognized chronic diseases, such as cardiovascular diseases, cancer, renal disorders, liver disease, diabetes mellitus; the use of antiepileptic or cholesterol-lowering drugs; recognized vitamin deficiency in the past; and serum folate concentrations below the lower value of the reference range (6–24 nmol/L). All participants were asked to follow their usual diet during the trial: the coffee-consuming groups were permitted to drink the type of coffee to which they were accustomed. Body weight and blood pressure were monitored throughout the 6-wk period in the 3 intervention groups. Each participant was seen at 3 visits that were spaced 3 wk apart. Dietary habits were recorded at the start and end of the trial. Nonfasting blood samples were drawn at the time of random assignment and 3 and 6 wk after the start of the trial. Effect Variables Plasma tHcy was measured by using the Abbott IMX homocysteine assay (Abbott Laboratories, Abbott Park, IL; CV: 4%). Total cholesterol was measured by an enzymatic assay analyzed on a Cobas Integra instrument (Roche, Basel, Switzerland; CV: 3%). The effects on the biochemical variables were assessed as the differences between the first and the last measurement within each group, as well as the differences between the changes within the Groups [NOTE: the former comparisons are not informative because there is no way to estimate change in caffeine intake from baseline.] The dietary habits were assessed at the beginning and end of the trial with a validated Norwegian food-frequency questionnaire. After the intervention period, the participants were asked about their self-perceived changes in the intake of important foods and drinks. Height, weight, and blood pressure were recorded at the beginning of the trial and after 6 wk. Statistical Methods Statistical analyses were carried out by using the computer program SPSS version 9.0 for WINDOWS (SPSS Inc, Chicago). The paired t test was used for the comparison of the differences of the biochemical variables taken between the start of the trial and after 6 wk. To adjust for possible confounding effects on the differences of tHcy and total cholesterol, analysis of covariance as well as multiple linear regression analyses with sex, age, change in body mass index (BMI), alteration in folate concentrations, and self-reported intake of tea and fruit juice were carried out. Statistical significance was P < 0.05.
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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
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List additional health endpoints (separately). 2 Plasma total homocysteine (tHcy)
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List additional health endpoints (separately).3 Plasma total cholesterol (TC)
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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 tHcy was measured by using the Abbott IMX homocysteine assay (Abbott Laboratories, Abbott Park, IL; CV: 4%). Total cholesterol was measured by an enzymatic assay analyzed on a Cobas Integra instrument (Roche, Basel, Switzerland; CV: 3%); method of BP measurement not reported.
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Caffeine (general)
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Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other? Coffee
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Measured or self reported? Self-report
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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.) After 6 weeks, the >/= 4 cups/day and 1-3 cups/day groups compared to the abstainer group
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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) Sex, age, change in body mass index (BMI), alteration in folate concentrations, and self-reported intake of tea and fruit juice
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What conflicts of interest were reported? No information provided
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Refid 11522552
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What were the sources of funding? Supported by grants from the Institute for Scientific Information on Coffee and the Physiological Effects of Coffee.
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Results & Comparisons

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