Calcium is essential for maintaining the necessary level of bone mass to support the structures of the body. If a person?s diet does not include enough calcium then body will take calcium away from the bones, which weakens them and makes them more likely to fracture. It is especially important for children and teens to have enough calcium to aid the development of their bones and bone mass. Intake of more than 2000 milligrams of calcium per day can be harmful to the kidneys and cause kidney stones. All the Bone & Joint Care information is available in this section.