CALCIUM POTENTIATES THE EFFECT OF ESTROGEN AND CALCITONIN ON BONE MASS - REVIEW AND ANALYSIS

We reviewed published clinical trials that measured bone mass of postm enopausal women from at least one skeletal site to evaluate whether ca lcium supplementation influenced the efficacy of estrogens and intrana sal calcitonin on bone mass change. We compared results of the adminis tration of oral estrogen or nasal calcitonin in conjuction with additi onal calcium intake either through diet or supplements compared with t hose of estrogen or calcitonin alone. Of the 31 published estrogen tri als analyzed, 20 modified the diet or used a calcium supplement (total 1183 mg/d) and 11 did not (total 563 mg/d). The mean increase in bone mass of the lumbar spine when estrogen was given alone was 1.3%/y (n = 5) compared with 3.3%/y when estrogen was given in conjunction with calcium (n = 14; P = 0.01). The mean increase in bone mass of the femo ral neck with estrogen alone (n = 3) was only 0.9%/y compared with 2.4 %/y when calcium was given with estrogen (n = 6; P = 0.04). Similarly, forearm bone mass increased 0.4%/y with estrogen alone (n = 7) compar ed with 2.1%/y when estrogen was given with calcium (n = 12; P = 0.04) . Similar results were found when weighted means were calculated. Of t he seven published trials evaluating the effects of 200 IU nasal salmo n calcitonin, six also used calcium supplements (total 1466 mg/d) wher eas one used calcitonin alone (total 627 mg/d). Bone mass of the lumba r spine increased 2.1% with calcitonin plus calcium supplementation co mpared with -0.2%/y with calcitonin alone. These results suggest that a high calcium intake potentiates the positive effect of estrogen on b one mass at all skeletal sites and perhaps that of calcitonin on bone mass of the spine.