Calcium is a mineral that helps bones stay strong. Our bodies continually remove small amounts of calcium from our bones and replace it with new calcium, a bone "remodeling" process. If the body removes more calcium from bones than it replaces, they slowly become weaker and more prone to breaking. Eating a diet rich in calcium allows the body to deposit calcium in bones so they stay strong.
The body actively builds bone and muscle throughout childhood and into early adulthood. All children gain bone (also called bone accrual) at different rates based upon their genetic potential and environmental factors. Healthy children will reach their genetic potential if they maintain a healthy lifestyle. This is similar to other aspects of growth such as linear growth and weight gain. Children with chronic health conditions may have multiple risk factors for impaired weight gain, linear growth, and bone accrual. Some forms of poor growth and bone accrual in early childhood can be ameliorated or partially overcome with nutrition and exercise.