The antioxidants found in a number of foods including chocolate (both dark and milk) may help prevent changes in cells that potentially lead to cancer and heart disease. These antioxidant levels are measured in what's referred to as ORAC units. The Agricultural Research Service (ARS) part of the USDA has determined ORAC values for a number of foods, including many fruits and vegetables as well as nuts, spices and chocolate.

Dark chocolate contains twice the ORAC level as milk chocolate and both rank right up there with raisins, prunes, blueberries, kale and strawberries. So, yes, milk chocolate has benefits too but you get twice the bang for your buck with the dark chocolate in terms of its antioxidant rating.