The Effect of Chronic Coffee Drinking on Blood Pressure

Abstract

Abstract-We sought to assess the effect of coffee consumption on blood pressure in humans. Our data sources included a MEDLINE search of the literature published before December 1997, bibliography review, and expert consultation. We selected controlled trials in which coffee consumption was the only difference between the intervention and control groups, mean blood pressure change was reported for each group or period, and treatment lasted for Ͼ24 hours. Of 36 studies initially identified, 11 (522 participants) met these inclusion criteria. Information on sample size, study design, participant characteristics (gender, race, age, baseline blood pressure, and antihypertensive medications), and treatment results were abstracted by 3 reviewers using a standardized protocol. Treatment effect of coffee consumption on blood pressure was estimated with the use of a random-effects model. In the 11 trials, median duration was 56 days (range, 14 to 79 days), and median dose of coffee was 5 cups/d. Systolic and diastolic blood pressure increased by 2.4 (range, 1.0 to 3.7) mm Hg and 1.2 (range, 0.4 to 2.1) mm Hg, respectively, with coffee treatment compared with control. Multiple linear regression analysis identified an independent, positive relationship between cups of coffee consumed and subsequent change in systolic blood pressure, independent of age of study participants and study design characteristics. The effect of coffee drinking on systolic and diastolic blood pressure was greater in trials with younger participants. Our findings provide support for a relationship between coffee consumption and higher blood pressure. Trials of coffee cessation of longer duration and in persons with hypertension should be performed. (Hypertension. 1999;33:647-652.)Key Words: blood pressure Ⅲ coffee Ⅲ meta-analysis Ⅲ clinical trials I t has long been suspected that coffee consumption may have adverse effects on the cardiovascular system. Some 1-5 but not all 6 -10 cross-sectional studies have identified a positive association between coffee drinking and blood pressure. At least one prospective study 11 has shown that coffee drinking is associated with an increase in blood pressure. Inferences regarding causality, however, must be made with caution from observational studies because other characteristics associated with coffee drinking may underlie the observed relationships.Experimental studies provide the best opportunity to determine whether a relationship is causal and whether an intervention, such as coffee cessation, has therapeutic relevance. In 1934, Horst et al 12 reported on a clinical trial of coffee drinking in hypertensive patients. Since then, Ͼ36 experimental investigations of the effects of coffee consumption on blood pressure in humans have been published. However, most of these trials have been small and cannot provide definitive results. The effects of coffee drinking on heart rate and the question of whether the health effects of coffee drinking differ according to the method used for brewing have also been controve...

Tea or coffee? A case study on evidence for dietary advice

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Coffee, caffeine and blood pressure: a critical review

“…Studies which compared caffeine tablets with decaffeinated coffee were excluded. According to the meta-analysis, systolic and diastolic blood pressure increased by 0.8 mmHg (P`0.001) and 0.5 mmHg (P`0.01), respectively, for every cup of coffee during long-term coffee consumption (Jee et al, 1999).…”

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