For people with hypertension, eating dark chocolate can significantly reduce blood pressure. Researchers writing in the open access journal BMC Medicine combined the results of 15 studies into the effects of flavanols, the compounds in chocolate which cause dilation of blood vessels, on blood pressure.
Dr Karin Ried worked with a team of researchers from the University of Adelaide, Australia, to conduct the analysis. She said, "Flavanols have been shown to increase the formation of endothelial nitric oxide, which promotes vasodilation and consequently may lower blood pressure.
There have, however, been conflicting results as to the real-life effects of eating chocolate. We've found that consumption can significantly, albeit modestly, reduce blood pressure for people with high blood pressure but not for people with normal blood pressure".
The pressure reduction seen in the combined results for people with hypertension, 5mm Hg systolic, may be clinically relevant - it is comparable to the known effects of 30 daily minutes of physical activity (4-9mm Hg) and could theoretically reduce the risk of a cardiovascular event by about 20% over five years. The researchers are cautious, however, "The practicability of chocolate or cocoa drinks as long-term treatment is questionable", said Dr Ried.
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More information: Does chocolate reduce blood pressure? A meta-analysis, Karin Ried, Thomas Sullivan, Peter Fakler, Oliver R Frank and Nigel P Stocks, BMC Medicine 2010, 8:39 doi:10.1186/1741-7015-8-39