青春期学生膳食钙和蛋白质对骨量的影响

摘要

目的 探索北京郊区青春期学生的膳食钙及蛋白质摄入与全身和股骨颈骨量之间的关系.方法 多层随机整群抽样的方法,选取北京怀柔区342名12～16岁学生(男生170人,女生172人).采用3d24h膳食回顾调查问卷了解膳食摄人情况.采用双能X线骨密度测量仪(Dual-energy X-rays absorptiometry,DXA)测量全身及股骨颈骨量.结果 研究对象平均每天膳食钙和蛋白质摄人量分别为316mg和70g.多元逐步回归分析发现:无论低钙组或高钙组中,体重和身高都是全身和股骨颈骨密度(bone mineral density,BMD)、骨矿物含量(bone mineral content,BMC)的主要影响因素,其他影响因素还包括性别、年龄、能量和钙、蛋白质、脂肪、碳水化合物及铁等营养素.调整性别、年龄、身高等混杂因素时,全身BMD、BMC在高钙低蛋白组最高(分别为0.804 g/m2,2010 g),而在低钙高蛋白组最低(分别为0.708 g/m2,1660 g;P ＜0.05).股骨BMD在高钙低蛋白组(0.809 g/m2)最高,BMC在低钙低蛋白组(3.8g)最高,而两者均在高钙高蛋白组最低(0.752 g/m2,3.51g;P ＜0.05).进一步调整体重后,上述差异的显著性消失.结论 除性别和年龄等不可控因素外,对北京郊区学生全身和股骨颈骨量影响最大的是体重和身高.对于钙摄入量不足的北京郊区青春期少年,高蛋白质、低钙饮食通过影响体重的变化间接地对全身和股骨颈BMD、BMC产生不利影响.%Objective To explore the relationship between dietary calcium and protein intake and bone mass of the total body and the femur in adolescents of rural area of Beijing. Methods A total of 342 12-16-year-old students (170 boys and 172 girls) in Huairou district, Beijing, were selected using multi-layer random cluster sampling method. A consecutive 3-day-food questionnaire was used to understand the dietary intake. Dual energy X-ray absorptiometry (DXA ) was used to measure the bone mass of total body and the femur. Results The mean daily intakes of dietary calcium and protein were 316mg and 70g, respectively. Multiple stepwise regression analysis showed that either in low calcium intake or high calcium intake group, body weight and height were main influential factors of BMD and BMC of total body and the femoral neck. Other influential factors included gender, age, energy, calcium, protein, fat, carbohydrate, iron, and other nutrient intakes. Under unadjusted factor conditions, the total body BMD and BMC were highest in high-calcium and low-protein group (0. 804 g/m2, 2010 g, respectively) , but were lowest in low-calcium andhigh-protein group (0.708 g/m2, 1660 g; P <0. 05). BMD of the femoral neck was highest in high-calcium and low-protein group (0. 809 g/m2) , and BMC of the femoral neck was highest in low-calcium low-protein group (3. 8g). The lowest BMD and BMC appeared in high-calcium and high-protein group (0.752 g/m2, 3.51g, respectively, P <0. 05). However, after adjusting for gender, age, height, and other confounding factors, the difference was still significant. After further adjustment of body weight, the above differenceswere not significant. Conclusion Except gender, age, and other uncontrollable factors, body weight and height are the most important factors of bone mass of total body and the femoral neck in adolescents of rural Beijing. High protein and low calcium intake may have a negative impact on BMD and BMC of the total body and the femoral neck, in adolescents of rural Beijing with insufficient calcium intake, by influencing their body weights.