It is never too early for individuals to start protecting their bones. A clinical trial of preadolescent girls found that they need to increase their calcium intake to build bone mass and prevent osteoporosis in old age. The current study, reported recently in the American Journal of Clinical Nutrition and the Journal of Nutrition, is the first analysis involving bone development in girls aged 8 to 13. The 354 participants were tracked for up to 7 years. The results of the study demonstrated that girls'bone mass increased significantly when they supplemented their calcium intake.