There may be good news for people looking for an excuse to munch on a couple of squares of chocolate after a review showed the treat could reduce blood pressure. 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. 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.