Chocolate shown to reduce blood pressure
I have heard that drinking tea and eating chocolate could have a beneficial effect on blood pressure and this trial caught my eye as a result. The aim of this meta-analysis was to ascertain if randomised trial data could support this notion.
Ten randomised controlled trials, five assessing the effect of cocoa on blood pressure and five assessing the effect of tea (black or green) on blood pressure, were identified. A total of 173 participants were included in the cocoa trials and 343 in the tea trials. Participants in the cocoa trials received cocoa products (typically around 100g of flavanol-rich chocolate per day) for a median duration of two weeks. Those in the tea trials received around four to six cups of tea per day for a median duration of four weeks. All trials had before and after blood pressure readings.
The results showed that the cocoa groups achieved a mean reduction in systolic pressure of 4.7mmHg (95% CI, -7.6 to -1.8 mmHg; P = 0.002) and a mean reduction in diastolic pressure of 2.8 mmHg (95% CI, -4.8 to -0.8 mmHg; P = 0.006) compared with controls.
In contrast, tea intake had no significant effect on blood pressure. Those in the tea group had a mean increase in systolic pressure of 0.4mmHg (95% CI, -1.3 to 2.2 mm Hg; P =0 .63) and a mean reduction in diastolic pressure of 0.6mmHg (95% CI, -1.5 to 0.4 mm Hg; P = 0 .38) compared with the control group.
The magnitude of blood pressure reduction in the cocoa groups is impressive and comparable with that seen in trials of antihypertensive drug monotherapy. Such a reduction would yield substantial reductions in the risk of stroke, coronary disease and death.
Although the total number of participants in the studies was small, it would appear that eating chocolate can reduce your blood pressure but tea will not.
Oh well, you can't have everything.
Taubert D, Roesen R, Schomig E. Effect of cocoa and tea intake on blood pressure. Arch Intern Med 2007;167:626-34Reviewer
Dr Peter Savill
GPSI Cardiology, Southampton