Effect of Cocoa and Tea Intake on Blood Pressure

Effect of Cocoa and Tea Intake on Blood Pressure
A Meta-analysis

Dirk Taubert, MD, PhD; Renate Roesen, PhD; Edgar Schömig, MD
Arch Intern Med. 2007;167:626-634.

Background Epidemiological evidence suggests blood pressure–lowering effects of cocoa and tea. We undertook a meta-analysis of randomized controlled trials to determine changes in systolic and diastolic blood pressure due to the intake of cocoa products or black and green tea.

Methods MEDLINE, EMBASE, SCOPUS, Science Citation Index, and the Cochrane Controlled Trials Register were searched from 1966 until October 2006 for studies in parallel group or crossover design involving 10 or more adults in whom blood pressure was assessed before and after receiving cocoa products or black or green tea for at least 7 days.

Results Five randomized controlled studies of cocoa administration involving a total of 173 subjects with a median duration of 2 weeks were included. After the cocoa diets, the pooled mean systolic and diastolic blood pressure were –4.7 mm Hg (95% confidence interval [CI], –7.6 to –1.8 mm Hg; P = .002) and –2.8 mm Hg (95% CI, –4.8 to –0.8 mm Hg; P = .006) lower, respectively, compared with the cocoa-free controls. Five studies of tea consumption involving a total of 343 subjects with a median duration of 4 weeks were selected. The tea intake had no significant effects on blood pressure. The estimated pooled changes were 0.4 mm Hg (95% CI, –1.3 to 2.2 mm Hg; P = .63) in systolic and –0.6 mm Hg (95% CI, –1.5 to 0.4 mm Hg; P = .38) in diastolic blood pressure compared with controls.

Conclusion Current randomized dietary studies indicate that consumption of foods rich in cocoa may reduce blood pressure, while tea intake appears to have no effect.

Author Affiliations: Department of Pharmacology, University Hospital of Cologne, Cologne, Germany.

Considerations:

This meta-analysis involved only a few studies with small sample sizes and short duration, limiting the statistical power and generalizability to long-term outcomes.

The researchers also cautioned that potential weight gain with the high-caloric cocoa diets "may reverse any blood pressure reductions during long-term habitual intake of cocoa products."

"We believe that any dietary advice must account for the high sugar, fat, and calorie intake with most cocoa products," they cautioned, but added, "it appears reasonable to allow phenol-rich cocoa products such as dark chocolate for calorie-balanced substitution of high-fat dairy products, sugar confectionary, or cookies of the usual diet."
The researchers reported no financial conflicts of interest

Link:

Taubert D, et al "Effect of Cocoa and Tea Intake on Blood Pressure: A Meta-analysis" Arch Intern Med. 2007;167:626-634.