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。     

性激素对青春早期学生骨量的影响

探讨不同性激素水平对青春早期学生的骨量增长的影响,为了解性激素与青春期骨骼发育关系提供理论依据.方法 整群抽取北京市怀柔区学生共197名,采用连续3d的24h膳食问卷回顾法了解膳食钙摄入情况.采用双能量X线骨密度测量仪(DEXA)测量全身骨量并计算出骨量年增长值及骨量年增长率,同时测定男生血清睾酮与女生血清雌二醇水平,按性激素水平P25和P75为界限将研究对象分为性激素水平高、中、低3组,比较3组间的骨量年增长值及年增长率.结果 男、女生不同性激素水平组间的膳食钙总摄入差异均无统计学意义(P值均>0.05).男生低睾酮组全身骨密度的年增长值和年增长率低于中睾酮组和高睾酮组(P值均<0.01),不同睾酮组间的骨矿物含量的年增长值和年增长率差异均无统计学意义(P值均>0.05).女生高雌二醇水平组全身骨密度、骨矿物含量的年增长值和年增长率显高于中雌二醇组和低雌二醇组(P<0.05).结论 青春早期学生性激素水平对骨量增长作用有性别差异,男生体内睾酮水平较高,骨密度年增长率也较高;女生体内雌二醇水平较高者的骨量年增长率较低.     

补充强化钙-维生素D牛奶中止两年后中学女生骨量的随访研究

目的:随访研究补充强化钙、维生素D牛奶中止2年后北京城区中学女生骨量的变化。方法:从完成1999-2001年补充强化钙和维生素D牛奶实验的698名女生(10.1岁)中随机抽取294名2年后进行随访,其中对照组未补充强化奶,实验1组强化钙奶,实验2组强化钙-维生素D奶。采用问卷调查法收集一般情况、膳食营养摄入、体力活动状况等指标,并检查其体格发育和第二性征发育状况。采用双能X线吸收仪(DEXA)测量全身、桡骨和前臂的骨量。结果:干预后两个实验组的桡骨远端1/3处、前臂远端1/3处和前臂远端1/10处的骨矿含量绝对增长值均显著高于对照组。但是,在干预中止两年后随访时三组间三个部位的骨矿含量增长值没有显著差异。结论:补充钙、维生素D强化牛奶后对女生骨量增长的促进作用均在中止两年后消失。     

广东大学生骨量与膳食营养体力活动的相关性

了解广东省大学生骨骼生长同发育现状及其与膳食营养摄入和体力活动水平的关系,为维护大学生骨骼正常生长发育提供参考.方法 采用双能X线骨密度测量仪,测量广东省212名18~ 22岁青年全身骨矿物含量(BMC)和骨密度(BMD).采用问卷调查方法获得研究对象膳食营养摄入及体力活动情况.结果 男生全身BMD(1.0 g/cm2)显著高于女生(0.9 g/cm2) (P<0.05),男生全身BMC(2 779.3 g)与女生(2 176.9 g)差异有统计学意义(P<0.05).女生膳食脂肪、维生素D摄入量与全身BMD、BMC均呈正相关(P值均<0.05),男生钙摄入量与BMD呈正相关,膳食能量、蛋白质、脂肪、维生素D摄入量及体力活动强度与全身BMD、BMC均呈正相关(P值均<0.05).结论 膳食营养素和体力活动可影响广东青年全身骨矿物含量和骨密度.     

钙摄入量对青春前期女童骨量增长的影响—两年随机干预实验

目的研究不同钙摄入量对于青春前期女童骨量增长的影响,为该人群钙适宜摄入量的修订提供科学依据。方法以年龄10.0±0.7岁的241名青春前期健康女童为对象,设计普通膳食组、牛奶补充组和钙剂补充组三组,总钙摄入量分别为600、900和1200mg/d,进行2年干预,采用多次称量及3d膳食询问法获得2年间日均膳食钙摄入量,使用双能X线骨密度仪测量干预前后全身、腰椎及近端股骨骨矿物密度和骨矿物含量。结果2年间三组的平均钙摄入量分别为552±61、864±139和1166±207mg/d;日均钙摄入量与全身、多位点骨矿物含量和骨矿物密度显著正相关;当日均钙摄入量达到864mg/d时,全身骨矿物含量增加值显著高于钙摄入量为552mg/d膳食组;当日均钙摄入量达到1166mg/d时,股骨颈骨矿物含量及骨矿物密度和腰椎骨矿物密度的增加值显著高于未达到1166mg/d的干预组。结论9～11.5岁的青春前期女童钙摄入量达到1166mg/d,全身特别是负重部位能获得较高骨矿物含量和骨矿物密度增长,提示青春前期钙适宜摄入量可能为1200mg/d。     

四川省阿坝州藏羌和汉族儿童少年骨量影响因素分析

目的了解四川省阿坝州藏、羌、汉族儿童少年骨量的影响因素,为制定学生营养政策、预防骨质疏松提供基础资料和科学依据。方法采用问卷调查方式,收集四川省阿坝藏羌自治州1821名7～18岁藏、汉、羌族男、女生的膳食营养素摄入和体力活动情况,测量身高和体重;采用生物电阻抗仪测定体成分,并用双能X线吸收仪（DEXA）测定前臂近端1/3处和远端1/10处骨矿物含量（BMC）和骨面积（BA）。结果多元线性回归分析发现,瘦体重对前臂远端1/10处和前臂近端1/3处的BMD和BMC的变异贡献要高于其他因素,其标准偏回归系数分别为0.567,0.687,0.346和0.482;藏族、钙摄入量、体力活动能量消耗等因素对前臂远端1/10处BMD和BMC的作用有统计学意义,其标准化回归系数分别为0.094和0.061,0.034和0.022,0.034和0.024。结论体重（尤其是瘦体重）是儿童少年骨量的主要影响因素,民族、膳食营养素摄入、体力活动因素也是影响儿童少年骨量的重要因素。     

12～17岁少年钙代谢实验研究

目的通过钙代谢平衡实验探讨中国青春期少年的钙参考摄入量。方法从320名参与1年补钙实验4组12～17岁的少年中,每组随机抽取男、女生各10人,共80人。采用钙代谢平衡实验的方法。实验期共10d,膳食适应3d后,开始7d的代谢试验。收集研究对象试验期内摄入的食品、排出的粪便和尿液样品,用电感耦合等离子体发射光谱法测定样品中的钙含量。结果不同水平钙摄入组间的钙吸收量、粪钙排出量、钙储留量存在差异。钙表观吸收率女生平均为46.4%,男生68.7%。进行曲线拟合后,男生钙吸收率最高时的钙摄入量为665mg/d,女生钙吸收率达到平台时的钙摄入量为650mg。为了达到每日最大储留量,男生钙摄入量要达到545mg/d,女生要达到1055mg/d。结论中国12～17岁男生和女生的钙适宜摄入量有很大差别,男生钙适宜摄入量约为600～700mg/d,女生为1000～1100mg/d。     

新疆某高校医学生膳食钙摄入状况

了解大学生膳食钙的摄入水平,为合理指导学生膳食营养提供参考.方法 采用整群随机抽样的方法,抽取新疆某高校医学生530名,通过自行设计的半定量食物频率问卷对研究对象食物摄入量进行调查,并评价钙摄入水平.结果 男生谷薯类、蔬菜、禽畜类、蛋类摄入量高于女生,女生水果类摄入量高于男生,差异均有统计学意义(P值均<0.01).学生钙平均摄入量为601 mg/d,占DRIs的75.1%,未达到膳食营养素参考摄入量标准,其中男生为605 mg/d,女生为598 mg/d,差异无统计学意义(t=0.440,P>0.05);学生膳食钙主要来自植物性食物(67.82%),奶及其制品来源的钙占25.61%.结论 学生膳食钙摄入不足,建议增加富含钙的食物摄入量.     

强化钙与维生素D牛奶对北京城区小学女生骨量的影响

目的 :　探讨饮用钙与维生素 D强化牛奶对北京城区青春前期女生骨量的影响。方法 :　为期一年设有对照的双盲干预研究。将来自北京市西城区 9所小学平均年龄为 1 0 .1岁的女生 75 7名随机分为对照组 (n=2 5 9) :保持日常饮食 ;实验 1组 (n=2 3 8) :除日常饮食外 ,饮用钙强化牛奶 1 3 7ml/d,含钙 2 3 3 mg;实验 2组 (n=2 6 0 ) :除日常饮食外 ,饮用钙和维生素 D强化牛奶 1 3 7ml/d,其中钙 2 3 3 mg,VD 3 .3μg。使用 2 4 h回顾法了解食物摄入、体力活动问卷了解体力活动情况 ,用双能 X线吸收仪 (DEXA)测定全身和前臂骨量。结果 :　与干预前相比 ,实验组 2全身骨矿物密度 (BMD)的增长率显著高于实验 1组和对照组 (9.6 %、8.3 %和 8.0 % ,P=0 .0 0 2 ) ;实验 1组、实验 2组桡骨远端 1 /3处 BMC和骨面积的增长率显著高于对照组 (BMC:1 3 .0 %、1 2 .9%和1 1 .7% ,P=0 .0 1 6 ;骨面积 :2 .3 %、2 .0 %和 1 .5 % ,P=0 .0 1 0 ) ;实验 1组前臂远端 1 /1 0处 BMC和BMD的增长率显著高于对照组 (P=0 .0 0 7)。结论 :　饮用钙与维生素 D强化牛奶能促进青春前期女生骨量的增长 ,饮用钙和维生素 D强化牛奶促进骨量增长的作用比饮用钙强化牛奶明显     

四川阿坝州藏羌汉族儿童青少年骨量比较研究

目的 分析四川省阿坝藏羌自治州藏、羌和汉族儿童少年的骨量状况，为西部少数民族地区儿童青少年生长发育的研究提供依据。方法 用双能X线前臂骨密度测量仪（pDEXA）测量1822名7-19岁藏、羌、汉族男女学生前臂远端1／10处和近端1／3处尺骨和桡骨（Dist．R＋U，Prox．R＋U）以及近端1／10处桡骨（Prox．R）的骨矿物密度（BMD）、骨矿物含量（BMC）、骨面积（BA）。结果 11，16，18岁女生和12，16，17岁男生的前臂骨量各项指标民族间差别无统计学意义；其他多个年龄段，藏族学生前臂远端骨量（特别是9～12岁男生 Dist．R＋U BMD及Dist．R＋U BMC）、前臂近端骨面积（Prox．R＋U BA）和近端桡骨骨面积（Prox，R BA）显著高于汉族和羌族；羌族学生骨量水平处于藏族和汉族之间；汉族13岁女生Dist．R＋U BA和Prox．R BMD显著高于本族同龄男生．羌族11岁女生Prox．R＋U BMC和Pwx．R BMC以及1l，12岁女生Dist．R＋U BA显著高于本族同龄男生，藏族15岁女生Dist．R＋U BA显著高于本族同龄男生，在其他年龄段各项骨量指标均为男生大干或等于女生。不同民族出现骨量性别差异的年龄不尽相同；男生在13-18岁、女生在11～16岁，Prox．R＋U BMD增长幅度明显大于Dist．R＋U BMD。结论四川藏、羌、汉族儿童青少年骨量存在差异。是否为遗传因素起作用尚需进一步深入研究。     

Effect of habitual dietary calcium intake on calcium supplementation in 12-14-y-old girls

BACKGROUND: There is no agreement on how much calcium young girls need for optimal bone mineralization. OBJECTIVE: We evaluated whether the effect of calcium supplementation on whole-body bone mineral accretion depends on habitual calcium intake. DESIGN: This was a randomized, double-blind, placebo-controlled, 1-y calcium intervention study of girls aged 12-14 y selected from a larger group according to habitual calcium intake: subgroup A (n = 60) habitually consumed 1000-1307 mg/d (40th-60th percentile), and subgroup B (n = 53) habitually consumed <713 mg/d (<20th percentile). The girls from each subgroup were randomly assigned to receive either 500 mg Ca/d or placebo. Whole-body bone mineral content (BMC), bone area (BA), bone mineral density (BMD), and BMC adjusted for BA, height, and weight (size-adjusted BMC) were measured at baseline and after 1 y. RESULTS: There was no significant effect modification of baseline habitual calcium intake on the relation between calcium supplementation and height, weight, BMC, size-adjusted BMC, BA, BMD, or alkaline phosphatase. Calcium supplementation had an effect on BMD (0.8%; P = 0.049) and tended to show signs of an effect on size-adjusted BMC (0.5%; P = 0.08). CONCLUSION: A modest effect of calcium supplementation on BMD was shown. However, the effect was independent of habitual calcium intake.     

青春期学生膳食营养状况对骨量的影响

目的研究学生青春期膳食营养状况对骨量的影响,以增加骨峰值,预防骨质疏松的发生.方法抽取贵阳某高等院校239名青春期学生进行一般情况和食物摄入情况调查,再从摄入豆类、奶类和同时摄入豆类、奶类的学生中抽取60人分为3组,用双能X线骨密度仪测定前臂1/3处骨密度(BMD)及骨矿化物含量(BMC).结果 60例学生的热能及多种营养素的摄入水平很低,尤其是钙摄入量仅占现行供给标准的39%;结果还显示BMD降低率高达58.3%.3组学生的BMD、BMC差异无显著性.BMC、BMD与身高、体重及食物中蛋白质、能量、钙、磷等摄入量呈正相关.结论骨量较低与其膳食营养素摄入低有关.应加强营养宣教,提高膳食营养状况以增加骨量.     

Factors that affect bone mineral accrual in the adolescent growth spurt

The development of bone mass during the growing years is an important determinant for risk of osteoporosis in later life. Adequate dietary intake during the growth period may be critical in reaching bone growth potential. The Saskatchewan Bone Mineral Accrual Study (BMAS) is a longitudinal study of bone growth in Caucasian children. We have calculated the times of maximal peak bone mineral content (BMC) velocity to be 14.0 +/- 1.0 y in boys and 12.5 +/- 0.9 y in girls; bone growth is maximal approximately 6 mo after peak height velocity. In the 2 y of peak skeletal growth, adolescents accumulate over 25% of adult bone. BMAS data may provide biological data on calcium requirements through application of calcium accrual values to factorial calculations of requirement. As well, our data are beginning to reveal how dietary patterns may influence attainment of bone mass during the adolescent growth spurt. Replacing milk intake by soft drinks appears to be detrimental to bone gain by girls, but not boys. Fruit and vegetable intake, providing alkalinity to bones and/or acting as a marker of a healthy diet, appears to influence BMC in adolescent girls, but not boys. The reason why these dietary factors appear to be more influential in girls than in boys may be that BMAS girls are consuming less than their requirement for calcium, while boys are above their threshold. Specific dietary and nutrient recommendations for adolescents are needed in order to ensure optimal bone growth and consolidation during this important life stage.     

补充钙剂对青春期骨矿含量的影响

为研究补充钙剂对青少年骨矿含量以及体格发育的影响 ,选取 1 61例 9～ 2 0岁健康青少年 ,按性别和性发育程度分为补钙组和对照组。实验前后评价两组膳食钙摄入量、运动量水平、性发育程度 ,并测定两组青少年身高、体重和桡骨远端 1 3处骨矿含量、骨宽和血清总碱性磷酸酶水平。结果表明本组青少年膳食钙摄入量低于每日膳食钙参考摄入量的适宜摄入量水平 ,补充钙剂对青少年身高、体重无明显影响 ;骨矿含量增长除女性青春期后期有显著性差异外 ,其余各组增长与对照组比较无显著性。结果提示 ,青春期存在体格快速发育和骨量迅速积累的特点 ,补充钙剂对骨矿含量的增长作用有限 ,对体格发育也无明显影响 ;在女性骨量增长较少阶段补充钙剂则可能有助于骨矿含量的增加 ,且这种作用可能通过降低骨代谢率实现     

Bone mass in Chinese premenarcheal girls: the roles of body composition, calcium intake and physical activity

The association of growth and anthropometric characteristics and lifestyle factors with bone mass and second metacarpal radiogrammetry parameters was evaluated in 373 healthy Chinese premenarcheal girls aged 9-11 years. Bone mineral content (BMC) and density (BMD) and bone area (BA) of distal forearm, proximal forearm and total body, bone mineral-free lean (BMFL) mass and fat mass were measured by dual-energy X-ray absorptiometry. Metacarpal bone periosteal and medullary diameters were measured. Dietary intakes were assessed by 7 d food record and physical activity (PA) by questionnaire. BMFL and fat mass together explained 6.3 and 51.6% of the variation in total body BMC and BMD, respectively. BMFL mass contributed to a substantial proportion of the variation in forearm BMC and BMD and periosteal diameter (10.4-41.0%). The corresponding BA explained 14.8-80.4% of the variation in BMC. Other minor but significant predictors of total body bone mass were Ca intake, height, age and PA score (BMD only), and of forearm bone mass were PA score, bone age, height and fat mass. Nevertheless, after adjusting for bone and body size and for age or bone age, subjects with Ca intake above the median (417 mg/d) had 1.8% greater total body BMC (P<0.001), and subjects with PA scores above the median had 2.4-2.5% greater distal and proximal forearm BMC (P<0.05) than those below. Vitamin D intake negatively associated with medullary diameter (partial R2 1.7%). The results indicate that premenarcheal girls should be encouraged to optimise nutrition and Ca intake and exercise regularly to achieve maximum peak bone mass.     

Calcium supplementation and bone mineral accretion in adolescent girls: an 18-mo randomized controlled trial with 2-y follow-up

BACKGROUND: A recent meta-analysis raised doubt as to whether calcium supplementation in children benefits spine and hip bone mineral density (BMD). OBJECTIVE: We used state-of-the-art measures of bone (fan-beam dual-energy X-ray absorptiometry and 4 bone turnover markers) to determine whether girls with low habitual calcium intake benefited from supplementation with a soluble form of calcium (calcium citrate malate dissolved in a fruit drink). DESIGN: The trial was an 18-mo randomized trial of calcium supplementation (792 mg/d) with follow-up 2 y after supplement withdrawal. Subjects were 96 girls (mean age: 12 y) with low calcium intakes (mean: 636 mg/d). The main outcome measure was change in total-body, lumbar spine, and total hip bone mineral content (BMC) during supplementation and 2 y after supplement withdrawal. Changes in BMD and bone turnover markers were secondary outcome measures. RESULTS: The mean additional calcium intake in the supplemented group was 555 mg/d. Compared with the control group, the supplemented group showed significantly (P < 0.05) greater gains in BMC (except at the total hip site) over the 18-mo study. BMD change was significantly (P < 0.05) greater for all skeletal sites, and concentrations of bone resorption markers and parathyroid hormone were significantly (P < 0.01) lower in the supplemented group than in the control group after 18 mo. After 42 mo, gains in BMC and BMD and differences in bone resorption were no longer evident. CONCLUSIONS: Calcium supplementation enhances bone mineral accrual in teenage girls, but the effect is short-lived. The likely mechanism for the effect of the calcium is suppression of bone turnover, which is reversed upon supplement withdrawal.