There was no effect of calcium supplementation  on femoral neck or lumbar spine BMD .
There was no evidence of effect modification by baseline calcium intake , sex , ethnicity , physical activity or pubertal stage .
While there is a small effect of calcium supplementation in the upper limb , the increase in BMD which results is unlikely to result in a clinical ly significant decrease in fracture risk .
The results do not support the use of calcium supplementation  in healthy children as a public health intervention .
These results can not be extrapolated to children with medical conditions affecting bone metabolism
BACKGROUND Clinical trials have shown that  calcium supplementation in children can increase  bone mineral density ( BMD ) although this effect may not be maintained .
There has been no quantitative systematic review of this intervention .
To determine the effectiveness of calcium supplementation for improving BMD  in children .
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To determine if any effect varies by sex , pubertal stage , ethnicity or level of physical activity , and if any effect persists after supplementation is ceased .
The effect of calcium supplementation on bone density during lactation and after weaning.
BACKGROUND Women may lose bone during lactation because of calcium lost in breast milk . We studied whether calcium supplementation prevents bone loss during lactation or augments bone gain after weaning . METHODS We conducted two r and omized , placebo-controlled trials of calcium supplementation ( 1 g per day ) in postpartum women . In one trial ( the study of lactation ) , 97 lactating and 99 nonlactating women were enrolled a mean ( + /-SD ) of 16+/-2 days post partum . In the second trial ( the study of weaning ) , 95 lactating women who weaned their infants in the 2 months after enrollment and 92 nonlactating women were enrolled 5.6+/-0.8 months post partum . The bone density of the total body , lumbar spine , and forearm was measured at enrollment and after three and six months . RESULTS The bone density of the lumbar spine decreased by 4.2 percent in the lactating women receiving calcium and by 4.9 percent in those receiving placebo and increased by 2.2 and 0.4 percent , respectively , in the nonlactating women ( P<0.001 for the effect of lactation ; P= 0.01 for the effect of calcium ) . After weaning , the bone density of the lumbar spine increased by 5.9 percent in the lactating women receiving calcium and by 4.4 percent in those receiving placebo ; it increased by 2.5 and 1.6 percent , respectively , in the nonlactating women ( P<0.001 for the effects of lactation and calcium ) . There was no effect of either lactation or calcium supplementation on bone density in the forearm , and there was no effect of calcium supplementation on the calcium concentration in breast milk . CONCLUSIONS Calcium supplementation does not prevent bone loss during lactation and only slightly enhances the gain in bone density after weaning
There was no effect of calcium supplementation  on femoral neck or lumbar spine BMD .
There was no evidence of effect modification by baseline calcium intake , sex , ethnicity , physical activity or pubertal stage .
While there is a small effect of calcium supplementation in the upper limb , the increase in BMD which results is unlikely to result in a clinical ly significant decrease in fracture risk .
The results do not support the use of calcium supplementation  in healthy children as a public health intervention .
These results can not be extrapolated to children with medical conditions affecting bone metabolism
BACKGROUND Clinical trials have shown that  calcium supplementation in children can increase  bone mineral density ( BMD ) although this effect may not be maintained .
There has been no quantitative systematic review of this intervention .
To determine the effectiveness of calcium supplementation for improving BMD  in children .
.
To determine if any effect varies by sex , pubertal stage , ethnicity or level of physical activity , and if any effect persists after supplementation is ceased .