Nutrition and bone health in children and adolescents.

Bone accretion during childhood is proportional to the rate of growth. During this time, interval height velocity is relatively slow for both boys and girls. As a direct consequence of this, calcium retention in the body of an average child is lower than the calcium retention in an adolescent. Bone size, bone mass, and bone mineral areal density of the regional skeletal sites increase on average by about 4%/yr from childhood to late adolescence and young adulthood, when most of the bone mass is accumulated. Calcium needs are greater during adolescence (pubertal growth spurt) than in childhood or adulthood. According to calcium balance studies, the threshold in take for adolescents is about 1500 mg/d. Inadequate calcium intake during growth may increase the risk of childhood fractures and predispose certain individuals to a lower peak bone mass.