Effect of calcium supplementation on bone mineral accretion in Gambian children accustomed to a low-calcium diet.

Background: Rural Gambian children have poor growth, delayed puberty, a low bone mineral content, and a low calcium intake. Objective: We investigated the effect of a calcium supplement on bone mineral accretion in rural Gambian children. Design: A randomized, double-blind, placebo-controlled study was conducted in 160 children (80 boys, 80 girls) aged 8.3-11.9 y. Bone mineral content (BMC), bone mineral density (BMD), and BMC adjusted for bone width, body weight, and height (size-adjusted BMC) were measured at the midshaft and distal radius. Each child received either 1000 mg Ca/d (as calcium carbonate) or a placebo 5 d/wk for 12 mo. Supplementation increased calcium intake from 342 to 1056 mg/d (8.6 to 26.4 mmol/d). Results: Calcium supplementation resulted in a higher BMC, BMD, and size-adjusted BMC (x difference ± SE): midshaft radius-BMC (3.0 ± 1.4%; P = 0.034), BMD (4.5 ± 0.9%; P ≤ 0.0001), and size-adjusted BMC (4.6 ± 0.9%; P ≤ 0.0001); distal radius-BMC (8.4 ± 3.2%; P = 0.009), BMD (7.0 ± 2.7%; P = 0.011), and size-adjusted BMC (5.5 ± 2.7%; P = 0.042). Supplementation had no significant effect on height, weight, or bone width at the midshaft radius or distal radius. At the end of the study, the calcium group had a significantly lower mean plasma osteocalcin concentration than the placebo group after adjustment for baseline concentration, sex, and pubertal status (-21.9 ± 6.5%; P = 0.001). Conclusions: Increased calcium intake resulted in increased bone mineral status, possibly in association with a decreased bone remodeling space. Further studies are needed to determine whether an increased calcium intake has long-term benefits in Gambian children.