补钙对青年女性全身各部位骨密度的影响

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

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。

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 Conclusions a peak value group 1 and group 2 ; however, they were not significantly different between group 3 and group 4 BMD increases in young Chinese women along with the increase of calcium intake. It may reach when the calcium intake reaches 1 000 mg/d, which may be regarded as an optimal calcium intake for Chinese young women.