CALCIUM SUPPLEMENTATION AND BONE-MINERAL DENSITY IN ADOLESCENT GIRLS

Objective.-To evaluate the effect of calcium supplementation on bone a cquisition in adolescent white girls. Design.-A randomized, double-bli nd, placebo-controlled trial of the effect of 18 months of calcium sup plementation on bone density and bone mass. Subjects.-Ninety-four girl s with a mean age of 11.9+0.5 years at study entry. Setting.-Universit y hospital in a small town. Interventions.-Calcium supplementation, 50 0 mg/d calcium as calcium citrate malate; controls received placebo pi lls. Main Outcome Measures.-Bone mineral density and bone mineral cont ent of the lumbar spine and total body were measured by dual-energy x- ray absorptiometry and calcium excretion from 24-hour urine specimens. Results.-Calcium intake from dietary sources averaged 960 mg/d for th e entire study group. The supplemented group received, on average, an additional 354 mg/d of calcium. The supplemented group compared with t he placebo group had greater increases of lumbar spine bone density (1 8.7% vs 15.8%; P=.03), lumbar spine bone mineral content (39.4% vs 34. 7%; P=.06), total body bone mineral density (9.6% vs 8.3%; P=.05), and 24-hour urinary calcium excretion (90.4 vs 72.9 mg/d; P=.02), respect ively. Conclusions.-Increasing daily calcium intake from 80% of the re commended daily allowance to 110% via supplementation with calcium cit rate malate resulted in significant increases in total body and spinal bone density in adolescent girls. The increase of 24 g of bone gain p er year among the supplemented group translates to an additional 1.3% skeletal mass per year during adolescent growth, which may provide pro tection against future osteoporotic fracture.