An analysis of 20 studies showed that eating dark chocolate daily resulted in a slight reduction in blood pressure.

The Cochrane Group’s report said chemicals in cocoa, chocolate’s key ingredient, relaxed blood vessels.

However, there are healthier ways of lowering blood pressure.

The theory is that cocoa contains flavanols which produce a chemical in the body called nitric oxide. This “relaxes” blood vessels making it easier for blood to pass through them, lowering the blood pressure.

An analysis of 20 studies showed that eating dark chocolate daily resulted in a slight reduction in blood pressure

However, studies have thrown up mixed results. The Cochrane analysis combined previous studies to see if there was really an effect.

There was a huge range in the amount of cocoa consumed, from 3 g to 105 g a day, by each participant. However, the overall picture was a small reduction in blood pressure.

A systolic blood pressure under 120 mmHg (millimetres of mercury) is considered normal. Cocoa resulted in a 2-3 mmHg reduction in blood pressure. However, the length of the trials was only two weeks so the longer term effects are unknown.

Lead researcher Karin Ried, from the National Institute of Integrative Medicine in Melbourne, Australia, said: “Although we don’t yet have evidence for any sustained decrease in blood pressure, the small reduction we saw over the short term might complement other treatment options and might contribute to reducing the risk of cardiovascular disease.”

High blood pressure is both common and deadly. It has been linked to 54% of strokes worldwide and 47% of cases of coronary heart disease.

However, chocolate packs plenty of fat and sugar as well as cocoa so is not the ideal way of lowering blood pressure.

There has also been a warning in the Lancet medical journal that dark chocolate may contain fewer flavanols than you might think. Dark chocolate contains a higher cocoa count than milk chocolate so should contain more flavanols, however, they can also be removed as they have a bitter taste.