Effect of a calcium and exercise intervention on the bone mineral status of 16-18-y-old adolescent girls.
What this study found
Calcium supplementation improved bone mineral status at several skeletal sites, with larger effects in more compliant participants. Among good compliers, effects were seen for whole body BMC 0.8 ± 0.3%, lumbar spine 1.9 ± 0.5%, ultradistal radius 1.3 ± 0.6%, total hip 2.7 ± 0.6%, femoral neck 2.2 ± 0.7%, and trochanter 4.8 ± 0.9%. Exercise had no significant intention-to-treat effect on size-adjusted BMC overall, but participants attending >50% of sessions showed increases at total hip 1.4 ± 0.7% and trochanter 2.6 ± 1.2%. No interaction between calcium and exercise was detected, suggesting…
- Study & population
- Four-group intervention study in healthy 16 to 18-year-old female students from two sixth-form colleges in Cambridge, United Kingdom.
- Intervention
- Active calcium-supplemented participants received 1000 mg/day elemental calcium as calcium carbonate (Calcichew-500), given orally as 2 chewable tablets per day, one midmorning and one late afternoon, for 15.5 months.
- Key limitation
- Per-arm sample sizes were modest, especially for subgroup and compliance analyses.
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Open PDFOriginal abstract
BACKGROUND Osteoporosis may be prevented or delayed by maximizing peak bone mass through diet modification and physical activity during adolescence. OBJECTIVE We studied whether increases in calcium intake and physical activity effectively increase the bone mineral status of adolescent girls aged 16-18 y. DESIGN We conducted a 15.5-mo study of calcium supplementation (1000 mg Ca/d as carbonate) in 144 adolescent girls aged 17.3 +/- 0.3 y ( +/- SD). The subjects were randomly allocated to an exercise (three 45-min exercise-to-music classes/wk during term time) or nonexercise group. Dual-energy X-ray absorptiometry of the whole body, spine, forearm, and hip was performed before and after intervention. RESULTS The mean (+/- SD) percentage of subjects compliant with supplement taking was 70 +/- 27% and with exercise class attendance was 36 +/- 25%. Baseline calcium intake was 938 +/- 411 mg/d. Calcium supplementation significantly increased size-adjusted bone mineral content. The effect was stronger in subjects with good compliance (percentage difference +/- SE): whole body, 0.8 +/- 0.3% (P < or = 0.01); lumbar spine, 1.9 +/- 0.5% (P < or = 0.001); ultradistal radius, 1.3 +/- 0.6% (P < or = 0.05); total hip, 2.7 +/- 0.6% (P < or = 0.001); femoral neck, 2.2 +/- 0.7% (P < or = 0.001); trochanter, 4.8 +/- 0.9% (P < or = 0.001). Attendance at > 50% of the exercise sessions was significant at the total hip (1.4 +/- 0.7%; P < or = 0.05) and trochanter (2.6 +/- 1.2%; P < or = 0.05). CONCLUSIONS Calcium supplementation and exercise enhanced bone mineral status in adolescent girls. Whether this is a lasting benefit, leading to the optimization of peak bone mass and a reduction in fracture risk, needs to be determined.