Effects of calcium supplementation on bone and other end-points in normal older women – The Auckland Calcium Study

.Calcium has been shown to have positive effects on bone mineral density in postmenopausal women. However, because these effects are small, it is unknown whether they are sustained with long-term use, they have not been shown with intention-to-treat analyses, and the evidence for fracture prevention with calcium monotherapy is inconsistent. We have conducted a randomized controlled trial of calcium (1 g/day as the citrate) in 1471 normal postmenopausal women (aged 74 ± 4 years) over 5 years, assessing the effects on bone, blood pressure, body weight and lipid levels.Calcium had a significant beneficial effect on bone density (intention-to-treat analysis), with between-groups differences at 5 years of 1.8% (spine), 1.6% (total hip) and 1.2% (total body). Serum alkaline phosphatase and PINP were lower in the calcium group at 5 years but fracture data were inconclusive. Calcium produced only transient changes in blood pressure, but sustained improvements in HDL/LDL cholesterol ratios. It had no effect on body weight but constipation was more common in the calcium group.We conclude that calcium results in a sustained reduction in bone loss and turnover, but its effect on fracture remains uncertain. Poor long-term compliance limits its effectiveness.