Context: Coffee is one of the most widely consumed beverages worldwide and is known to acutely raise blood pressure (BP), but the effects of chronic consumption on BP is unclear.
Objectives: To conduct a systematic review and meta-analysis of available randomized controlled trials (RCTs) and cohort studies to assess the effect of chronic coffee consumption on BP and the development of hypertension.
Data sources: Ovid, MEDLINE (from 1948), EMBASE (from 1988), and all of Web of Science and Scopus.
Study selection: RCTs and cohort studies of at least 1-week duration that assessed BP and/or the incidence of hypertension in coffee consumers compared with a control group that consumed less or no coffee.
Data extraction: Two authors independently reviewed abstracts and full-text articles for inclusion. Data were abstracted using standardized forms. Risk of bias in the RCTs was examined using the method described in the Cochrane Handbook for Systematic Reviews of Interventions. Quality of the cohort studies were assessed using the Newcastle–Ottawa quality assessment scale for cohort studies.
Data synthesis: Six hundred and ten articles were retrieved and a total of 15 (10 RCTs and five cohort studies) met inclusion criteria. Meta-analysis of RCTs demonstrated a pooled weighted difference in mean change in SBP of −0.55 mmHg [95% confidence interval (CI) −2.46 to 1.36) and DBP −0.45 mmHg (95% CI −1.52 to 0.61). Meta-analysis of the cohort studies demonstrated a pooled risk ratio for developing hypertension of 1.03 (95% CI 0.98–1.08).
Conclusion: Low-quality evidence did not show any statistically significant effect of coffee consumption on BP or the risk of hypertension. Given the quality of the currently available evidence, no recommendation can be made for or against coffee consumption as it relates to BP and hypertension.
aDivision of Preventive, Occupational, and Aerospace Medicine
bMayo Clinic Libraries, College of Medicine, Mayo Clinic, Rochester, Minnesota, USA
Correspondence to Mark Steffen, MD, Division of Preventive, Occupational, and Aerospace Medicine, Mayo Clinic, 200 First Street SW, Baldwin 5A, Rochester, MN 55905, USA. Tel: +1 507 284 3211; fax: +1 507 284 4251; e-mail: Steffen.email@example.com
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Received 2 March, 2012
Revised 13 July, 2012
Accepted 25 July, 2012