THE EFFECT OF CALCIUM SUPPLEMENTATION AND TANNER STAGE ON BONE-DENSITY, CONTENT AND AREA IN TEENAGE WOMEN

One hundred and twelve Caucasian girls, 11.9 +/- 0.5 years of age al e ntry, were randomized into a 24-month, double-masked, placebo-controll ed trial to determine the effect of calcium supplementation on bone mi neral content, bane area and bone density. Supplementation was 500 mg calcium as calcium citrate malate (CCM) per day. Controls received pla cebo pills, and compliance of both groups averaged 72%, Bone mineral c ontent, bone mineral area and bone mineral density of the lumbar spine and total body were measured by dual energy X-ray absorptiometry (DSA ). Calcium intake hom dietary sources averaged 953 mg/day for the enti re study group. The supplemented group received, on average, an additi onal 360 mg calcium/day from CCM. At baseline and after 24 months, the two groups did not differ with respect to anthropometric measurements , urinary reproductive hormone levels or any measurement of pubertal p rogression. The supplemented group had greater increases of total body bone measures: content 39.9% versus 35.7% (p = 0.01), area 24.2% vers us 22.5% (p = 0.15) and density 12.2% versus 10.1% (p = 0.005). Region -of-interest analyses showed that the supplemented group had greater g ains compared with the control group for bone. mineral density, conten t and area, In particular, In the lumbar spine and pelvis, the gains m ade by the supplemented group were 12%-24% greater than the increases made by the control group, Bone acquisition rates in the two study gro ups were further compared by subdividing the groups into those with be low- or above-median Values for Tanner score and dietary calcium intak e, In subjects with below-median Tanner scores, bone acquisition was n ot affected by calcium supplementation or dietary calicum level. Howev er, the calcium supplemented subjects with above-median Tanner had hig her bone acqusition rates than the placebo group with above-median Tan ner scores. Relative to the placebo group. the supplemented group had increased yearly gains of bone content, area and density which represe nted about 1.5% of adult female values. Such increases, if held to adu lt skeletal maturity, could provide protection against future risk of osteoporotic fractures.