Calcium supplementation with and without hormone replacement therapy to prevent postmenopausal bone loss

To determine whether augmentation of dietary calcium is effective in the prevention of early postmenopausal bone loss.

Three-arm, placebo-controlled, randomized parallel trial. The study duration was 2.9 +/- 1.1 (SD) years.

General community.

118 healthy, white women 3 to 6 years after spontaneous menopause, recruited by community announcement.

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.

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.

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).

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.