Here is some good news for chocolate lovers: dark chocolate may boost the function of vital endothelial cells that line the inside of blood vessels.Cocoa is rich in antioxidant compounds called flavonoids, which are also found in fruits,vegetables, wine and green tea. Research suggests that consumption of foods rich in flavonoids may decrease the risk of cardiovascular disease.The study was conducted by researchers at the Yale Prevention Research Center in Connecticut.  45 healthy people ranging from moderately overweight to obese took part in the study. The participants were divided into three groups that ate either eight ounces of cocoa without sugar; cocoa with sugar; or a placebo.

For six weeks, the participants underwent endothelial function testing.This test shows the ability of blood vessels to relax and expand in order to accommodate increased blood flow. The results showed that endothelial function improved  by 2.4 percent in the group that consumed cocoa with no sugar, compared with 1.5 percent in the group that ate cocoa with sugar. There was a 0.8 percent decrease in function in the group that ate the placebo. This does not suggest that people should start eating more chocolate but it does mean that flavonoid rich foods are good for heart health.