The flavonoids found in the cocoa that makes up hot chocolate also have a positive effect on arterial health. A particular study performed by the National Institutes of Health partially supported by Mars Chocolate company showed high amounts of improvement in blood flow after drinking a flavanol-rich cocoa drink. In the study, the subjects (27 people ages 18 to 72) drank a cocoa drink containing 900 milligrams of flavonols every day, which resulted in an improvement in blood flow and the function of endothelial cells that line blood vessels.