Effect of a calcium and exercise intervention on the bone mineral status of 16-18-y-old adolescent girls.
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.


METHODS
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.
Stear
Samantha J
SJ
MRC Human Nutrition Research, Cambridge, United Kingdom.
Prentice
Ann
A
Jones
Sarah C
SC
Cole
Tim J
TJ
D015502:Absorptiometry, Photon; D000293:Adolescent; D015519:Bone Density; D002119:Calcium Carbonate / Q000008:administration & dosage; D002136:Calcium, Dietary / Q000008:administration & dosage*; D019587:Dietary Supplements; D004311:Double-Blind Method; D015444:Exercise; D005260:Female; D005269:Femur; D005272:Femur Neck; D006801:Humans; D008159:Lumbar Vertebrae; D010349:Patient Compliance; D010919:Placebos; D011884:Radius
D002136:Calcium, Dietary; D010919:Placebos; D002119:Calcium Carbonate