Summary: Supplementation with elemental calcium 500 mg/day alone for 2 years is able to decrease bone turnover and is effective in retarding bone loss at lumbar spine and slowing bone loss at femoral neck in elderly Thai women who had low dietary calcium intake.

Introduction: Most elderly Thais have a total dietary calcium intake of less than the recommended amount. The aim of the study was to investigate the effect of calcium supplementation on bone mineral density and biochemical indices of bone remodeling in Thai postmenopausal women.

Methods: Four hundred and four healthy postmenopausal women 60 years old or older without osteoporosis were recruited and conducted in a randomized, double-blinded, placebo-controlled trial. They were randomly given elementary calcium 500 mg/day or placebo for 2 years. Dietary calcium intake was calculated from the nutrient compositional analysis of the 3-day food records. Serum 25 hydroxyvitamin D was measured by radioimmunoassay and bone turnover markers were determined by electrochemiluminescence immunoassay.

Results: The age of the subjects was 65.8 ± 4.4 years. All baseline characteristics of the subjects in the calcium-supplemented group and the placebo group were not statistically different. At the end of the study, significant decreases in serum C-terminal telopeptide of type I collagen and serum total procollagen type I amino terminal propeptide in the calcium-supplemented group were observed, while there was no change in the placebo group. In addition, plasma parathyroid hormone decreased, although not significantly, only in the calcium-supplemented group. Percent changes from baseline of lumbar spine (L2-L4) bone mineral density increased 2.76 % in the calcium-supplemented group and 0.87 % in the placebo group, whereas the percent changes from baseline of femoral neck decreased 0.21 % in the calcium-supplemented group and 0.90 % in the placebo group.

Conclusions: Calcium supplementation is necessary for the decrease of bone turnover and prevention of bone loss in Thai elderly women.