Does Calcium Supplementation Prevent Postmenopausal Bone Loss?

TLDR

The study evaluated whether daily 2000 mg calcium supplementation could prevent bone loss in early postmenopausal women over two years, comparing it to estrogen therapy and placebo. Forty‑three women were randomized to percutaneous estradiol, oral calcium, or placebo and had bone mineral content measured quarterly by single‑photon and dual‑photon absorptiometry. Estrogen maintained bone mineral content, whereas calcium and placebo groups experienced significant loss; calcium slowed cortical bone loss slightly but had no effect on trabecular bone, indicating it is less effective than estrogen for early postmenopausal bone preservation. N Engl J Med 1987; 316:173–7.

Abstract

During a two-year study, we examined the effect of calcium supplementation on postmenopausal bone loss in 43 women in the early postmenopausal period who were assigned to one of three treatment groups: (1) percutaneous 17β-estradiol (combined with progesterone during the second year), (2) oral calcium (2000 mg daily), and (3) placebo. All participants were examined every three months. Bone mineral content in the forearm (measured by single-photon absorptiometry) and in the entire body and spine (measured by dual-photon absorptiometry) remained constant in the estrogen-treated group but decreased significantly in the groups receiving calcium and placebo. In the calcium-treated group, we observed a tendency toward a slowed loss of compact bone (in the proximal forearm and total skeleton) as compared with the placebo group, while the rate of loss of trabecular bone (the distal forearm and spine) was the same as in the placebo group. Our preliminary data suggest that calcium supplementation in the dosage we used is not as effective as estrogen therapy for the prevention of early postmenopausal bone loss. Calcium supplementation may have had a minor effect on the loss of cortical bone, but it had no effect on the trabecular bone. (N Engl J Med 1987; 316:173–7.)