In a study, more than 460 ninth- and tenth-grade girls reported their activity levels, soda drinking habits, and history of bone fractures. A researcher found that drinking any type of soda was linked to an increased likelihood of having a bone fracture, and that the greatest increases were for those girls who drank cola beverages, and reported their physical activity as either high-level or vigorous. Researcher Grace Wyshak says that she doesn’t know why cola beverages or other soft drinks increase likelihood of bone fractures. One possibility is that cola drinks contain phosphoric acid, which has previously been shown to affect calcium metabolism and bone mass. Others believe that young people may be choosing to replace milk in their diets with soda, giving their growing bodies less calcium with which to make bones.