Calcium Supplementation Plays a Positive Role in Bone and Body Composition in Chinese Adolescents

The purpose of this study is to evaluate the effects of calcium supplementation at different levels on bone mineral accretion and body composition in Chinese adolescents with low habitual calcium intakes. A double-blind randomized controlled trial (RCT) of four doses of calcium supplementation given for 24 months to 257 (135 boys and 122 girls) healthy adolescents aged 12-15 years. The subjects were randomly assigned to four groups, each group receiving chewable calcium carbonate tablets providing elemental calcium at 63, 354, 660, or 966 mg/d, respectively. Bone mineral content (BMC) and bone mineral density (BMD) of the total body, lumbar spine and body composition were measured with dual-energy X-ray absorptionmetry. Information on dietary intakes and physical activity were collected with questionnaires. Subjects were re-classified as three groups by actual total calcium intakes while average total calcium intakes in each group were 386, 629 and 984 mg/d. After supplementation, BMC of total body in Group two (2464g) and Group three (2437g) were significant higher than that in Group one (2321g) in males. Similar significant differences in lean body mass and body weight (P<0.05) were also found in males. However, there were no significant differences among groups in females. Gender, puberty development, physical activity and calcium intakes played a significant role in BMC retention at total body in adolescents (Rc2=0.429). In conclusion, calcium supplementation more than 250 mg/d lasting for two years improves growth of BMC, lean body mass and weight in Chinese male adolescents with low habitual calcium intakes. Gender, tanner stage, physical activity and calcium intakes are the most important factors on BMC retention.