Research synthesisLow evidenceSmall effect4 studies · 1 beneficial · 3 neutral · 0 harmful
Across 4 studies, 1 reported a small beneficial effect of combined calcium and vitamin D supplementation on bone mineral density (BMD) in postmenopausal women with osteoporosis, while 3 studies showed neutral effects. The beneficial finding was statistically significant (p=0.01) in a meta-analysis of 869 participants. The median study duration was 297 days, and most studies enrolled clinical populations (postmenopausal women or kidney transplant recipients).
- Studied populations: postmenopausal women with osteoporosis; kidney transplant recipients; postmenopausal women with type 2 diabetes and high fracture risk
Caveats: Evidence base is small (only 4 studies) — conclusions should be considered preliminary. Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests. Only one study used a specific form (calcium/cholecalciferol), with neutral results; the single beneficial study used combined calcium and vitamin D, but the form was not reported. The beneficial effect was limited to pelvic BMD in postmenopausal women with osteoporosis and may not generalize to other populations or skeletal sites.
Generated Jul 12, 2026