In 2005, researchers at Athens Medical School (Greece) found that dark chocolate may decrease key markers of cardiovascular performance implicated in heart disease, high blood pressure, and stroke.  In the study, consumption of dark chocolate decreased wave reflections, exerted a beneficial effect on the lining of blood vessels and the lymphatic system, and did not stiffen arteries. Citing the high flavonoid (a type of antioxidant) content in dark chocolate, along with its observed ability to dilate (relax) arteries after consumption, the researchers concluded that “Chocolate may exert a protective effect on the cardiovascular system.” Previous research by University of California-Davis (USA) scientists found that as little as a handful (25 grams) of semi-sweet chocolate chips caused an increase in blood levels of flavonoids.

"The superiority of chocolate, both for health and nourishment, will soon give it the same preference over tea and coffee in America which it has in Spain ..." ~ Thomas Jefferson