Dark chocolate smooths blood flow
Eating dark chocolate can improve healthy blood flow and prevent clots forming in the veins, an international heart congress has heard.
But the same benefits might not be gained from eating milk chocolate.
The research by Greek scientists was presented at the European Society of Cardiology's meeting ESC Congress 2004.
The researchers said they had demonstrated for the first time how chocolate improved the function of blood vessels, allowing them to dilate, thereby preventing the formation of potentially damaging clots.
Blood clots, depending on where they form can lead to thrombosis, embolism, stroke, heart attack and angina.
Dr Charalambos Vlachopoulos, of the Hippokratian Hospital at the University of Athens, who presented the research, said that eating 100 grams of dark chocolate improved function in healthy young adults for at least three hours.
The study involved 17 volunteers who ate either 100 grams of dark chocolate or a non-chocolate substitute. On another day the groups were swapped over.
The results showed that functioning of the endothelium, a thin layer covering the innermost surface of blood vessels, was improved in the dark chocolate group but not in the group that ate the chocolate substitute.
The heart-protecting properties of dark chocolate, which contains high levels of a kind of antioxidant called flavonoids, have been acknowledged for some time.
But the latest research sheds new light on how the mechanism might work, by protecting blood vessels from the damaging effects of unstable oxygen compounds called free radicals.
Free radicals attack other atoms to stabilise themselves by stealing an electron, and in the process can damage cells.
Last year, a group of Italian and British scientists found plain chocolate increased levels of antioxidants in the blood by nearly 20%. Milk chocolate did not have the same effect, however, possibly because milk interferes with the absorption process.