New preliminary clinical data suggest that consumption of certain chocolates can affect platelet function in a positive fashion. Platelet aggregation and activation are factors that may play a role in the progression of cardiovascular disease. These findings were presented during a symposium at the 17th World Congress of the International Society for Heart Research. The recent human clinical trial was conducted by researchers at the University of California, Davis. They fed volunteers either 25 grams of semi-sweet chocolate pieces with a high flavonoid content or bread as a control. The chocolate pieces were manufactured for this study by the American chocolate company Mars Incorporated. The researchers obtained blood samples at baseline and two and six hours after consumption. They then measured platelet function using a diagnostic tool called the PFA-100. After platelet activation had been stimulated in vitro, the researchers measured the amount of time it took the platelets to fully close an opening simulating that of a blood vessel. For those subjects who had consumed the chocolate, closure time significantly increased in the two- and six-hour readings, suggesting a marked reduction in platelet reactivity. There was no significant effect seen after consumption of the bread. These results support earlier research that suggests that acute consumption of chocolate containing a relatively high level of flavonoids may be associated with a number of positive events relating to cardiovascular health. "More and more, we are finding evidence that consumption of chocolates that are rich in flavonoids can have positive cardiovascular effects," said Carl Keen, Ph.D., professor and chair, Department of Nutrition, professor, Department of Internal Medicine, University of California, Davis and lead researcher of the study. "We not only have observed an increase in antioxidant capacity after chocolate consumption, but also modulation of certain hormone like compounds and, now, platelet function." The symposium entitled "Flavonoid-Rich Foods - A Strategy for Potentially Preventing Heart Disease" was sponsored by Mars, Incorporated. It is the first time a scientific conference for cardiologists was devoted entirely to the effects of these flavonoids on cardiovascular health.