A square of dark chocolate a day can lower blood pressure without piling on the pounds, researchers claim today.
A team of German scientists concludes that a little dark chocolate could offer a much more attractive way for people with slightly high blood pressure to achieve small cuts, compared with traditional low fat diets that can be hard to stick to over the long term.
Previous research has indicated that consumption of high amounts of cocoa-containing foods can lower blood pressure, believed to be due to the action of the cocoa polyphenols, a group of chemical substances in plants that include heart beneficial kinds, called flavanols.
But one concern is that the benefits of a reduction in blood pressure contributed by the flavanols could be offset by the high sugar, fat and calories of chocolate.
To investigate, Dr Dirk Taubert of University Hospital of Cologne, Germany, and colleagues assessed did a trial on 44 adults with borderline high blood pressure, giving them either 6.3 g (30 calories) per day of dark chocolate containing 30 milligrams of polyphenols, or matching polyphenol-free white chocolate. "It was one little square of a 100-gram bar containing 16 squares," he told The Daily Telegraph.
The researchers report in the Journal of the American Medical Association that dark chocolate intake reduced average blood pressure without changes in body weight, blood plasma levels of fats or sugars. Hypertension prevalence declined from 86 percent to 68 percent. Blood pressure was unchanged in the white chocolate group.
Overall, they cut blood pressure by up to two millimetres of mercury with a square of chocolate each day. "Although the magnitude of the blood pressure reduction was small, the effects are clinically noteworthy," the team concluded.
Over a population, it has been estimated that a three millimetre mercury reduction in systolic blood pressure "would reduce the relative risk of stroke mortality by 8 percent, of coronary artery disease mortality by five percent, and of all-cause mortality by four percent," the authors write.
Many earlier studies have been sponsored by chocolate manufacturers. However, Dr Taubert said yesterday: "We had no contact with any chocolate manufacturer (chocolate is not too expensive)."
By Roger Highfield, Science Editor