Gain in bone mineral mass in prepubertal girls 3.5 years after discontinuation of calcium supplementation: a follow-up study

Background Calcium supplementation during childhood and adolescence increas es bone-mass accrual. Whether or not this benefit persists after discontinu ation of supplementation is not known. We previously showed a favourable ef fect of milk-extracted calcium phosphate incorporated in various foods on a ccumulation of bone mineral mass in 8-year-old girls. We now report the res ults of a follow-up study undertaken more than 3 years after the end of cal cium supplementation. Methods Anthropometric and bone variables were measured in 116 of the 144 g irls whose data had been studied at the end of the supplementation period. The mean time elapsed between the end of the intervention period and this f ollow-up measurement was 3.5 years. Areal bone mineral density was measured by dual-energy X-ray absorptiometry at the same six skeletal sites as thos e studied during the intervention phase. Findings We were able to remeasure 62 and 54 girls of the calcium-supplemen ted and placebo groups, respectively. The increase from baseline in the ove rall mean bone mineral density of the six skeletal sites was still highly s ignificant (calcium-supplemented group 179 mg/cm(2) [SE 8] vs placebo group 151 mg/cm(2) [7], p=0.012). A significant difference in favour of the supp lemented group was also seen with respect to mean bone mineral content (p=0 .031) and mean bone area (p=0.04). Difference in pubertal maturation did no t seem to account for the recorded differences. Interpretation Our results suggest that this form of milk-extracted calcium phosphate taken during the prepubertal period can modify the trajectory of bone mass growth and cause a long-standing increase in bone mass accrual, which lasts beyond the end of supplementation.