Calcium Supplementation with and without Hormone Replacement Therapy To Prevent Postmenopausal Bone Loss

OBJECTIVE: To determine whether augmentation of dietary calcium is effective in the prevention of early postmenopausal bone loss. DESIGN: Three-arm, placebo-controlled, randomized parallel trial. The study duration was 2.9 +/- 1.1 (SD) years. SETTING: General community. PARTICIPANTS: 118 healthy, white women 3 to 6 years after spontaneous menopause, recruited by community announcement. INTERVENTIONS: Random allocation to daily intake of 1700 mg of calcium (calcium carbonate given in divided doses with meals); placebo; or conjugated equine estrogens (0.625 mg; days 1 to 25), progesterone (10 mg; days 16 to 25), and 1700 mg of elemental calcium daily. Each participant received 400 IU of vitamin D daily. MAIN OUTCOME MEASURES: Total body calcium measured by delayed gamma neutron activation analysis and whole-body counting; bone mineral density of the spine, femur, and radius measured by photon absorptiometry. RESULTS: Bone mineral density declined in the placebo group for the lumbar spine (-2.1%/y; 95% Cl, -3.3 to -0.9), femoral neck (-2.0%/y; Cl, -2.6 to -1.2), trochanter (-1.6%/y; Cl, -2.4 to -0.8), Ward triangle (-2.7%/y; Cl, -3.7 to -1.7), and total body calcium (-2.0%/y; Cl, -2.2 to -1.8). Rates of change were intermediate for calcium augmentation compared with placebo and estrogen-progesterone-calcium but statistically significant compared with placebo for total body calcium (-0.5%/y; Cl, -0.9 to -0.1; P = 0.006) and the femoral neck (-0.8%/y; Cl, -1.4 to -0.2; P = 0.03). CONCLUSIONS: Although less effective than estrogen-progesterone-calcium, calcium augmentation alone significantly retards bone loss from the femoral neck and improves calcium balance in recently postmenopausal women. Dietary calcium augmentation should be recommended as a strategic option in helping to prevent early postmenopausal bone loss.