According to German researchers, foods rich in cocoa content appear to reduce blood pressure and tea may not have any effects at all.

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But that doesn’t mean the Journal of the American Medical Association condones or recommends large consumption of chocolate to decrease blood pressure, but research says it seems reasonable to substitute phenol-rich cocoa products like dark chocolate for those other fattening, unhealthy, and high calorie desserts.

"We believe that any dietary advice must account for the high sugar, fat and calorie intake with most cocoa products," the authors conclude.

"Rationally applied, cocoa products might be considered part of dietary approaches to lower hypertension risk."

Any individuals with hypertension should eat more vegetables and fruits.

Compounds known as polyphenols or flavonoids in fruits and vegetables are thought to contribute to their beneficial effects on blood pressure and cardiovascular risk.

"Tea and cocoa products account for the major proportion of total polyphenol intake in Western countries," the authors write. "However, cocoa and tea are currently not implemented in cardioprotective or anti-hypertensive dietary advice, although both have been associated with lower incidences of cardiovascular events."

Dr. Dirk Taubert and colleagues at the University Hospital of Cologne, Germany, conducted a meta-analysis of 10 trials, five of cocoa's effects on blood pressure and five involving tea.
The studies were either randomized trials, in which some participants were randomly assigned to cocoa or tea groups and some to control groups, or used a crossover design, in which participants' blood pressure was assessed before and after consuming cocoa products or tea.

The five cocoa studies involved 173 participants, including 87 assigned to consume cocoa and 86 controls, 34 per cent of whom had hypertension.

Four of the five trials reported a reduction in both systolic (the top number, when the heart contracts) and diastolic (the bottom number, when the heart relaxes) blood pressure.

Compared with those who were not consuming cocoa, systolic blood pressure was an average of 4.7 millimetres of mercury lower and diastolic blood pressure was an average of 2.8 millimetres of mercury lower.

The effects are comparable to those achieved with blood pressure lowering medications, the authors note.