The antioxidants in chocolate help block chemical changes in bad LDL cholesterol that lead to clogged arteries. In fact, Vinson found chocolate's antioxidants better than vitamin C at detoxifying LDLs. Research by Penny Kris-Etherton at Pennsylvania State University shows diets rich in dark chocolate or cocoa powder raise good HDL cholesterol. Chocolate antioxidants act like aspirin to reduce blood platelet stickiness and thus the clotting that triggers heart attacks and strokes. The cocoa significantly delayed blood-clotting time.
Chocolate packs fat and sugar, so overindulging does put on pounds.
But chocolate is not a prime cause of obesity, studies worldwide find. But moderate amounts do not appear harmful. Extensive research at Harvard found women who ate chocolate bars three or four times a week were no more apt to have heart disease than women who rarely ate chocolate. In excess, yes. A dark chocolate bar's 10-30mg is modest next to the 100mg in a cup of coffee.