The effect of prepubertal calcium carbonate supplementation on skeletal development in Gambian boys-a 12-year follow-up study.

CONTEXT: Calcium intake during growth is essential for future bone health but varies widely between individuals and populations. The impact on bone of increasing calcium intake is unknown in a population where low calcium intake, stunting, and delayed puberty are common.

OBJECTIVE

To determine the effect of prepubertal calcium supplementation on mean age at peak velocity for bone growth and mineral accrual.

DESIGN AND

SETTING

Prospective follow-up of boys in rural Gambia, West Africa, who had participated in a double-blind, randomized, placebo-controlled trial of calcium supplementation.

PARTICIPANTS

Eighty boys, initially aged 8.0-11.9 years, were followed up for 12 years.

INTERVENTIONS: Subjects received 1 year of calcium carbonate supplementation (1000 mg daily, 5 d/wk).

MAIN OUTCOME MEASURES: Dual-energy x-ray absorptiometry measurements were carried out for whole body (WB), lumbar spine, and total hip bone mineral content, bone area (BA), and WB lean mass. Super imposition by translation and rotation models was made to assess bone growth.

RESULTS

Age at peak velocity was consistently earlier in the calcium group compared to the placebo group, for WB bone mineral content (mean, -6.2 [SE, 3.1]; P = .05), WB BA (mean, -7.0 [SE, 3.2] mo; P = .03), lumbar spine and total hip BA. By young adulthood, supplementation did not change the amount of bone accrued (mineral or size) or the rate of bone growth.

CONCLUSIONS

Twelve months of prepubertal calcium carbonate supplementation in boys with a low calcium diet advanced the adolescent growth spurt but had no lasting effect on bone mineral or bone size. There is a need for caution when applying international recommendations to different populations.