The effect of milk supplements on calcium metabolism, bone metabolism and calcium balance

Abstract

Twenty-two healthy postmenopausal women were divided into two groups, one group of 13 received milk supplementation of 24 oz per day and the other group of 9 controls received no intervention during two years of observation. Extensive inpatient metabolic balance and radiocalcium kinetic studies were performed at the beginning and at the end of one year of observation. In the milk supplement group, fractional calcium absorption (x̄ ± SD) decreased from .243 ± .058 to .176 ± .058, absorbed calcium increased from .159 ± .052 gm/d to .248 ± .063 gm/d, urine calcium increased from .117 ± .034 gm/d to .146 ± .027 gm/d, bone accretation decreased from .385 ± .079 gm/d to .326 ± .063 gm/d, bone resorption decreased from .446 ± .098 gm/d to .342 ± .106 gm/d and endogenous fecal calcium increased from .105 ± .023 gm/d to .120 ± .021 gm/d. All these changes were significant within the group and the mean changes were significantly different from the mean changes observed in the control group. Calcium balance in the milk supplemented group improved from -.061 ± .056 gm/d to -.017 gm/d ± .073 gm/d. Predicted changes in calcium and bone metabolism held true except that the suppression of bone remodeling was less than previously found using calcium carbonate supplements. We conclude that milk and milk products can be recommended as sources of calcium, that data on the effects of increasing calcium intake from other sources can be applied to milk and that milk may offer an advantage because it does not suppress bone remodeling as severely as calcium carbonate.