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Cocoa, but Not Tea, Lowers Blood Pressure

  • Authors: News Author: Shelley Wood
    CME Author:
    Désirée Lie, MD, MSEd
  • CME Released: 4/11/2007; Reviewed and Renewed: 4/16/2008
  • Valid for credit through: 4/16/2009
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Target Audience and Goal Statement

This article is intended for primary care clinicians, cardiologists, and other specialists who care for patients at risk for hypertension.

The goal of this activity is to provide medical news to primary care clinicians and other healthcare professionals in order to enhance patient care.

Upon completion of this activity, participants will be able to:

  • Describe the effect of cocoa consumption on BP.
  • Describe the effect of tea consumption on BP.


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  • Shelley Wood

    Shelley Wood is a journalist for Medscape. She joined, part of the WebMD Professional Network, in 2000 and specializes in interventional cardiology. She studied literature at McGill University and the University of Cape Town and received her graduate degree in journalism from the University of British Columbia, specializing in health reporting. She can be reached at [email protected]


    Disclosure: Shelley Wood has disclosed no relevant financial relationships.

CME Author(s)

  • Désirée Lie, M.D., M.S.Ed.

    Clinical Professor, Family Medicine, University of California, Orange; Director, Division of Faculty Development, UCI Medical Center, Orange, California


    Désirée Lie, M.D., M.S.Ed. has disclosed no relevant financial relationships.

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Cocoa, but Not Tea, Lowers Blood Pressure

Authors: News Author: Shelley Wood CME Author: Désirée Lie, MD, MSEdFaculty and Disclosures

CME Released: 4/11/2007; Reviewed and Renewed: 4/16/2008

Valid for credit through: 4/16/2009


from Heartwire — a professional news service of WebMD

April 11, 2007 — More happy justification for chocolate lovers: blood pressure (BP) responds favorably to cocoa, but not tea, a new meta-analysis suggests. Authors of the study say that while both products are rich in polyphenols, the study findings suggest that phenols in cocoa may be more active than those in tea. The study appears in the April 9 issue of the Archives of Internal Medicine.

"Products rich in cocoa may be considered part of a blood pressure lowering diet, provided that the total energy intake does not increase," lead investigator for the study, Dirk Taubert, MD, PhD, from the University Hospital of Cologne in Cologne, Germany, told heartwire . "I believe that cocoa is healthier than other sugar confectionary or high-fat dairy products."

Cocoa Beats Tea for BP

For their study, Taubert and colleagues conducted a literature search for randomized parallel group or crossover studies evaluating the effects of cocoa products or black or green tea for at least 7 days. They identified 10 studies that met their inclusion criteria: 5 randomized trials evaluated cocoa consumption (median, 2 weeks of cocoa consumption) in a total of 173 subjects and 5 trials evaluated tea consumption in a total of 343 subjects (in whom tea consumption was measured for a median of 4 weeks). In both analyses, study participants were evenly split between active and control groups. In the cocoa studies, cocoa consumption was typically flavonol-rich chocolate in the range of 100 g per day; in the tea studies, consumption was in the range of 4 to 6 cups daily.

In the cocoa studies, systolic BP (SBP) and diastolic BP (DBP) dropped in the active group as compared with controls; however, in the tea studies, no differences were seen in BP between the 2 groups. The authors point out that while the 2 substances contain similar amounts of polyphenols, the components of these polyphenols differ between cocoa and tea: cocoa is particularly rich in procyanidins, whereas black and green tea are rich in flavan-3-ols and gallic acid. It may be that the polyphenol components in cocoa are more bioavailable, Taubert and colleagues propose.

Table. Change in Blood Pressure

Blood Pressure Pooled Change* (mm Hg) P
   Systolic -4.7 .002
  Diastolic -2.8 .006
  Systolic 0.4 .63
   Diastolic -0.6 .38


*Compared with control group.
Source: Arch Intern Med. 2007;167:626-634.

According to Taubert and colleagues, the effects of cocoa on SBP and DBP were comparable to those achieved with antihypertensive drugs. "The magnitude of the hypotensive effects of cocoa is clinically noteworthy; it is in the range that is usually achieved with monotherapy of β-blockers or angiotensin-converting enzyme inhibitors," they write. "At the population level, a reduction of 4 to 5 millimeters of mercury in SBP and 2 to 3 millimeters of mercury in DBP would be expected to substantially reduce the risk of stroke (by about 20%), coronary heart disease (by 10%), and all-cause mortality (by 8%)."

Dr. Taubert acknowledged to heartwire that studies of tea and cocoa have yielded contradictory results. "The inconsistencies may result from differences in research question and research focus," he said. For example, "the reported effects of polyphenols on blood pressure, endothelial function, or platelet aggregation may be caused by different mechanisms and different phenols. The transient effects observed after administration of single phenol doses may be differentiated from the sustained effects observed after multiple daily doses. Moreover, plant foods like cocoa or tea contain many different — 100 and more — phenol compounds, but so far, mechanistic studies have focused on the flavonol monomers catechin and epicatechin, for which significant bioavailability has been demonstrated. But these may not be the active ingredients as our meta-analysis indicates."

Dr. Taubert believes his study "will not put the debate to rest, but foster a new debate and, more important, new research in this field."

Arch Intern Med. 2007;167:626-634.

The complete contents of Heartwire , a professional news service of WebMD, can be found at, a Web site for cardiovascular healthcare professionals.

Clinical Context

According to the current authors, although there is some evidence that polyphenols contained in cocoa and tea may be beneficial for hypertension by causing arterial vasodilation and increasing endothelial production of nitric oxide, the human studies that have been done involve small numbers of patients with some studies reporting mixed results.

This is a meta-analysis of randomized controlled trials to quantitatively asses the effect of dietary cocoa or tea intake on BP by pooling the data contained in several trials.

Study Highlights


  • A search of MEDLINE, EMBASE, SCOPUS, the Cochrane Controlled Trials Register, and Science Citation Index was conducted for studies from 1966 to 2006 in any language.
  • Text words "cocoa," "chocolate," "tea," "blood pressure," "hypertension," "endothelium," and "cardiovascular" were used.
  • Inclusion criteria were full-text articles, randomized clinical trials with parallel group or crossover design, at least 10 patients, outcome measures of SBP or DBP or both, and confidence intervals in results.
  • Excluded were abstract-only articles and studies with use of vitamins or supplements in addition to cocoa or tea, duration of less than 7 days for studies, and incomplete control group information.
  • Data were extracted and assessed for methodologic quality by 2 independent assessors (κ = 0.89 - 0.94).
  • Trials were evaluated using the validated Jadad 11-item instrument with a maximum score of 13 points.
  • Studies with scores greater than 9 points were considered of high quality; 9 points or below, low quality.
  • Primary outcomes were changes in BP from baseline to after the intervention.
  • Potential publication bias was assessed by the funnel plots of each trial's effect size against the inverse standard error.
  • 3106 articles were identified and screened, and 10 met inclusion criteria.
  • Of 10 studies identified, 5 addressed cocoa, and 5 addressed tea intake and BP.
  • Most studies were excluded because of short duration of less than 7 days.
  • Mean quality scores were 9.2 for cocoa and 9.4 for tea studies.
  • Funnel plots suggested no significant asymmetry.
  • The cocoa studies had a combined total of 173 individuals allocated to cocoa (n = 87) or control (n = 86). 64% were men, and 34% had hypertension.
  • The dose of cocoa ranged from 240 to 480 kcal/day of energy with 500 mg of polyphenols or 213 to 294 mg of flavonols and procyanides daily.
  • Controls consumed white chocolate with no polyphenol-containing cocoa.
  • 4 of 5 cocoa studies reported a reduction of SBP and DBP after consumption.
  • The 1 study reporting no change in BP used the lowest dose of cocoa.
  • The pooled BP change was -4.7 mm Hg (P = .002) and -2.8 mm Hg, respectively, for SBP and DBP.
  • This level of BP reduction is usually achieved with β-blockers or angiotensin-converting enzyme inhibitors.
  • According to the authors, a decrease in SBP of 4 to 5 mm Hg and in DBP of 2 to 3 mm Hg would be expected to reduce the risk for stroke by 20%, risk for heart disease by 10%, and risk for all-cause mortality by 8%.
  • BP was most likely to be reduced in young individuals with mild essential hypertension, and reduction was less likely in elderly subjects with hypertension and younger subjects with normal BP.
  • There was considerable heterogeneity for the cocoa studies.
  • The tea studies had a total of 343 subjects allocated to tea (n = 171) or control (n = 172).
  • Black tea was used in 4 studies, and green tea was used in 1 study. The dose of polyphenols ranged from 500 to 1350 mg daily (5 - 6 cups of tea daily).
  • 71% were men, and 49% had hypertension in the tea studies.
  • None of the tea studies were associated with significant alterations in SBP or DBP.
  • There was no heterogeneity between the tea studies.
  • The negative results of the tea studies were independent of age, hypertension duration, and study duration.

Pearls for Practice

  • Cocoa consumption is associated with lowering of SBP and DBP in individuals with hypertension and individuals with normal BP.
  • Tea consumption is not associated with BP lowering in individuals with hypertension and individuals with normal BP.

CME Test

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