In 2005, the results of a study conducted by researchers at the Athens Medical School in Athens, Greece was published which examined the effect of flavonoid-rich dark chocolate on the cardiovascular system. They concluded that consumption of dark chocolate “may exert a beneficial effect on endothelial function in healthy adults” and that “chocolate consumption may exert a protective effect on the cardiovascular system” as a whole.
In February 2006, Dutch scientists published a study in the Archives of Internal Medicine which examined diet of 470 elderly men and health outcomes, using data from the larger Zutphen Elderly Study in the Netherlands. The results were that the men who consumed foods mad from cacao beans, such as hot chocolate, chocolate bars, or chocolate pudding, had lower blood pressure and a 50% lower risk of death than those men that did not eat chocolate.
Although more research needs to be done on this topic, these preliminary results suggest that if you desire a healthy heart, dark chocolate is the key, likely due to the unique phytonutrients within cacao.
If interested in learning more, the scientific paper can be found within the American Journal of Hypertension, Volume 18, Issue 6, pages 785-791.