Effects of calcium and vitamin D supplementation on hip bone mineral density and calcium-related analytes in elderly ambulatory Australian women: a five-year randomized controlled trial.

Five-year randomized controlled trial in community-dwelling ambulant women aged 70 to 80 years in Perth, Western Australia, who were not receiving bone-active medications. Participants were allocated 1:1:1 to calcium alone, calcium plus vitamin D, or control.

Active supplementation consisted of calcium carbonate 600 mg twice daily with food for 5 years. The calcium plus vitamin D arm received the same calcium regimen plus ergocalciferol 1000 IU once daily; the control arm received placebo vitamin D.

Overall, adding vitamin D to calcium produced the most durable benefit, with no bone loss at the hip over 5 years and evidence of reduced bone turnover. Hip bone mineral density was maintained versus control at year 1 in both the calcium group (1.5 Ϯ 0.5%, P ϭ 0.007) and the calcium plus vitamin D group (1.2 Ϯ 0.6%, P ϭ 0.04), but only the calcium plus vitamin D group retained benefit at years 3 and 5 (2.8 Ϯ 1.1%, P ϭ 0.01; 2.2 Ϯ 1.1%, P ϭ 0.05). The calcium plus vitamin D group also had lower alkaline phosphatase at year 1, 3, and 5 (11.3 Ϯ 2.9%, P Ͻ 0.001; 8.7 Ϯ 3.9%, P ϭ 0.03; 11.3 Ϯ 5.7%, P ϭ 0.05) and lower urinary DPD/Cr at year 5 versus control and calcium (−27.6 Ϯ 8.6%, P ϭ 0.002; −17.5 Ϯ 7.7%, P ϭ 0.03). The authors concluded that vitamin D with calcium improves bone density in elderly women even in a sunny climate, whereas calcium alone did not sustain hip BMD over the full 5 years.

Arm sizes were modest (Ca N = 40, CaD N = 39, control N = 41), which limits precision and power for subgroup and biomarker analyses. The study was conducted in older women from a single Australian city, so generalizability to men, younger adults, or other settings is limited. The intervention effect was strongest for calcium plus vitamin D, while calcium alone showed less durable benefit over 5 years.