In Brief: Cocoa beats tea
Cocoa beats tea
Researchers in Germany conducted a meta-analysis comparing the effects cocoa products and tea had on blood pressure. It wasn't close: While cocoa significantly reduced blood pressure according to the five studies in the analysis, the five studies of tea showed no effect. Systolic blood pressure (the top number) fell, on average, by 4.7 mm Hg in the cocoa studies, and diastolic blood pressure (the bottom number) by 2.8 mm Hg.
That may not seem like very much of a decrease, but it's comparable to the effect you get from taking a beta blocker or an ACE inhibitor. And a drop that size translates into a 20% lower risk for stroke and 10% lower risk for heart attack.
Like cocoa, tea is loaded with polyphenols, the chemicals that are presumably responsible for relaxing blood vessels so blood pressure drops. The quantity of polyphenol intake is pretty similar in the tea and cocoa studies.