People who eat a bar of dark chocolate in the morning and drink a glass of red wine at night are lowering their blood pressure and so prolonging their lives.

Even better would be to also cut down on salt and step up exercise, Adelaide University’s Karin Ried said.

“Eating chocolate reduces blood pressure by about 2-3 millimetres of mercury (while) exercise and other dietary measures can reduce blood pressure by 3-7 millimetres.”

Reid and her team of fellow Australians picked apart 20 studies involving 856 participants that looked at the effect on blood pressure of a daily dose of cocoa for two weeks.

Cocoa is rich in flavanols, which are known to dilate blood vessels and so allow blood to flow more freely. “Smaller dosages may be as effective as larger dosages,” she said. But a 100-gram bar of dark chocolate would be a handy dosage.

Flavanols are also present in green tea, dark berries and red wine. Salt is known to elevate blood pressure. Exercise helps reduce blood pressure.

“Dark chocolate has 50-85 per cent cocoa and milk chocolate up to 30 per cent,” Ried said. “As the flavanol content is responsible for blood pressure reduction, cocoa-rich foods are preferable.”

Unsurprisingly, only one in 20 of those who agreed to help the march of science by eating a daily bar of chocolate reported any unpleasant side effects. The study was reported in the Cochrane Library.