Dairy calcium, bone metabolism, and prevention of osteoporosis

Single-photon absorptiometry was used to measure the bone mineral content of young adults, osteoporotic patients, and age-matched controls without bone disease. A retrospective dietary survey was made to study the relationship between calcium intake and bone mineral content at different periods of life. The bone mineral content and bone mineral density of young adults are directly related to the calcium intake through milk and diary products. Calcium intake through milk and milk products in childhood and adolescence had been significantly lower in patients than in the controls; for the later periods of life (both the 20 to 30 yr prior to the study and at the time of the study), no significant differences existed between the calcium intakes of the two groups. Adequate calcium intake also protected against increased bone resorption, as evidenced in particular by the reduced serum osteocalcin, a parameter of bone turnover. The data support the hypothesis that adequate calcium intake through milk and milk products in childhood and adolescence is a decisive marker for attaining maximum bone mass (peak adult bone mass) and for the prevention of osteoporosis. The recommended dietary allowances of calcium have been fixed to 1200 mg/d for the age group between 10 and 24 yr. However, in Germany, calcium was undersupplied by up to 50% in the diet of children and adolescents.