补钙对青年女性全身各部位骨密度的影响

目的探讨不同钙摄入量对我国青年女性全身及各部位骨密度的影响,为进一步研究制定我国居民钙的适宜摄入量提供科学依据。方法为期13个月设有对照的双盲干预研究。将某军校平均年龄19.8岁女学员179人,以基线调查的全身骨密度及膳食钙摄入量为指标,随机分为4组,每天给予不同剂量碳酸钙片,使总钙摄入量分别达到400、800、1000及1200mg/d,每片钙片中均强化60IU的维生素D。干预前后分别使用食堂记帐法、称重法和24小时记录法了解膳食摄入,体力活动问卷了解体力活动情况,双能X线骨密度仪测定全身、腰椎和前臂的骨密度。结果4组平均摄入的膳食钙加上补充钙的中位数分别是517mg/d(1组)、810mg/d(2组)、964mg/d(3组)、1185mg/d(4组)。实验前后各部位骨密度增加值的组间比较分析显示,3组和4组的全身、下肢和尺骨远端1/3处骨密度增加值均显著高于1组和2组(P<0.05);3组和4组的3处骨密度增加值差异均无显著性。结论随着钙摄入量的增加,青年女性全身各部位骨密度增加,当钙摄入量达到约1000mg/d时,全身、下肢和尺骨远端1/3处骨密度增加值达到最大,再增加钙摄入至1200mg/d时,骨密度不再显著增加。提示我国青年女性钙的适宜摄入量可能在1000mg/d左右。

Effect of Calcium Supplementation on Bone Mineral Density in Chinese Young Women

Objective To explore the effect of calcium supplementation on bone mineral density(BMD)in Chinese young women and to identify the adequate calcium intake level.Methods A thirteen-month double-blind randomized intervention trial was conducted.Totally 179 healthy young women(aged 19-21)were recruited and then randomly divided into four groups.The total calcium intake combined with the dietary calcium intake and calcium supplementation for each group were about 400,800,1 000,and 1 200 mg/d,respectively.Calcium tablet fortified with 60 IU vitamin D was intaken three times per day.Dietry intake was mainly assessed by 24-hour recall and physical activity was assessed by questionnaire.The BMD of the whole body,lumbar vertebrae,and non-dominant forearm were measured by dual energy X-ray absorptiometry.Results All the subjects were divided into four groups according to their average totle calium intake(supplement calcium dietry calcium):517 mg/d for group 1,810 mg/d for group 2,964 mg/d for group 3,and 1 185 mg/d for group 4.The increased values of BMD of the whole body,lower limbs,and ulna in group 3 and group 4 were significantly larger than those in group 1 and group 2;however,they were not significantly different between group 3 and group 4.Conclusions BMD increases in young Chinese women along with the increase of calcium intake.It may reach a peak value when the calcium intake reaches 1 000 mg/d,which may be regarded as an optimal calcium intake for Chinese young women.