Cologne, Germany - More happy justification for chocolate lovers: blood pressure responds favorably to cocoa, but not tea, a new meta-analysis suggests [1]. 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.

"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, Dr Dirk Taubert (University Hospital of Cologne, Germany), told heartwire. "I believe that cocoa is healthier than other sugar confectionaries or high-fat dairy products."

For their study, Taubert et al 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 seven days. The randomized trials identified in their search involved a total of 173 subjects evaluated in five cocoa-consumption studies (median two weeks of cocoa consumption) and five studies of tea consumption in a total of 343 subjects (in whom tea was consumption was measured over a median of four weeks). In both analyses, study participants were evenly split between active and control groups. In the cocoa studies, cocoa consumption was typically flavanol-rich chocolate in the range of 100 g per day; in the tea studies, consumption was in the range of four to six cups daily.

In the cocoa studies, systolic and diastolic blood pressure dropped in the active group, as compared with controls; however, in the tea studies, no differences were seen in blood pressure between the two groups. The authors point out that while the two substances contain similar amounts of polyphenols, the components of these polyphenols differ between cocoa and tea: cocoa is particularly rich in procyanidins, while 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 et al propose.

According to Taubert and colleagues, the effects of cocoa on systolic and diastolic blood pressure 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 beta blockers or angiotensin-converting enzyme inhibitors," they write. "At the population level, a reduction of 4 to 5 [mm Hg] in systolic blood pressure and 2 to 3 [mm Hg] in diastolic blood pressure would be expected to substantially reduce the risk of stroke (by about 20%), coronary heart disease (by 10%), and all-cause mortality (by 8%)."

To heartwire, Taubert acknowledged 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 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 or more—phenol compounds, but so far, mechanistic studies have focused on the flavanol monomers catechin and epicatechin, for which significant bioavailability has been demonstrated. But these may not be the active ingredients, as our meta-analysis indicates."

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