Calcium, phosphorus and human bone development.

Calcium intakes by girls and adult females should approximate or exceed the Recommended Dietary Allowances so that peak bone mass can be achieved during early adulthood and bone mass can be maintained thereafter until the menopause. Investigations of the relationship between dietary calcium consumption and measurements of bone mass or density strongly support the contention that adequate intakes of calcium by females contribute to greater values of bone mass through adolescence and into adulthood. Prospective studies have especially been robust in support of this relationship. Inadequate calcium intakes early in life may lead to low bone mass because of several possibilities. Three potential mechanisms for the development of low bone mass are proposed, and in all a role for elevated parathyroid hormone is emphasized. A likely mechanism contributing to low bone mass in the United States involves a low calcium:high phosphorus intake ratio, but this possibility has not been adequately tested with a prospective design. Future investigations are needed to address the etiologic risk factors influencing less than optimal development of bone mass in females living in affluent nations.