儿童、青少年骨矿含量影响因素多元岭回归分析

目的：分析儿童青少年时期骨量发育状况和年龄、体格发育及膳食因素对骨矿含量的影响。方法：以问卷表收集了161名健康9～20岁儿童青少年性发育程度、运动及饮食情况并测定体格发育状况：采用单光子骨密度仪检测桡骨骨矿含量和骨宽。结果：男、女生骨矿含量水平均随年龄增长而明显增加；性发育水平、骨宽以及身体质量指数对骨矿含量有较明显的作用；膳食钙摄入量与骨矿含量呈正相关，膳食磷和膳食纤维与骨矿含量呈负相关。结论：男、女性骨矿含量在整个青春期都处于不断增长过程中，性发育程度、身体质量指数与骨矿含量密切相关；骨宽对骨矿含量影响较大。膳食纤维与骨矿含量呈负相关，注意增加膳食钙摄入量，调整膳食钙、磷比例等因素有助于儿童、青少年骨矿含量的提高。     

学龄前儿童膳食管理现状及干预效果评价

了解学龄前儿童膳食中营养素摄入状况,探讨钙摄入量与生长发育的关系.方法 在武汉市中心城区三餐制示范性幼儿园中随机抽取16所幼儿园儿童5 664名作为研究对象,回顾性调查前3个月的膳食钙摄入量及其他重要营养素摄人量,测量儿童身高、体重,分析钙摄入量与身高、体重五级评价分布关系;采用前瞻性调查分析方法将其中4所低钙摄入量幼儿园分为实验组(113人)和对照组(121人),干预研究1 a后,比较两组膳食中钙摄人量水平以及儿童身高、体重年增长平均值.结果 16所幼儿园横断面现场调查表明,按照我国制定的推荐摄入量RNI标准,幼儿膳食中蛋白质、能量、铁、锌摄入量符合标准,钙摄入量较低(41.9%~81.0%);膳食中钙摄人量占RNI比例<50%组与≥80%组中儿童身高五级评价分布差异有统计学意义(P<0.01).干预后,实验组与对照组儿童平均身高增长值分别为(7.25±0.96),(5.69±0.85) cm,差异有统计学意义(P<0.05),实验组钙摄入水平明显提高.结论 膳食中长期严重缺钙可影响儿童体格发育,并使身高生长速率减缓.幼儿园儿童膳食中钙的摄人量应达到标准供给量80%以上.     

中晚期妊娠钙营养干预对孕妇骨健康影响的探讨

目的:探讨妊娠期不同方式钙干预对孕期妇女骨健康的影响。方法:对59名26~36岁健康孕妇进行膳食调查,随机分为3组,即孕中期补钙组、孕晚期补钙组和对照组。在各组能量和营养素摄入相近的情况下,分别对研究组进行不同方式的钙营养支持干预。结果:孕期膳食钙摄入量每天不足450mg,孕妇血清钙、磷稳定,不随着钙摄入量的增加而改变;补充钙剂后可以增加骨钙含量。结论:孕妇膳食钙摄入量较低,但其血钙、血磷水平相对恒定,不受钙摄入量的影响,经补充钙剂有助于改善孕妇骨钙储备。     

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。     

早产与足月产儿青春期体格和性发育水平比较

目的 比较早产与足月产儿青春期体格发育和性发育水平，分析早产对青春期体格和性发育的影响。方法 对99名早产与99名足月产的12～15岁初中生进行身高、体重测定，同时评定第二性征发育水平，询问首次遗精和月经初潮的年龄。结果 2组青少年的身高、体重发育水平差异无统计学意义；早产男童的阴毛发育水平落后于足月产儿，首次遗精年龄大于足月产儿；早产女生的乳房发育水平落后于早产儿，月经初潮年龄大于足月产儿。结论 早产儿青春期虽然在体格发育方面赶上足月产儿，但性发育水平仍落后于足月产的同龄青少年。     

学龄前儿童长期补充碳酸钙制剂效果的研究

目的研究碳酸钙长期补充对学龄前儿童骨量、钙、铁代谢的影响。方法以成都市幼儿园123名3～6岁儿童为研究对象。将入选的儿童随机分成试验组与对照组。试验组每日服用300mg钙(6日／周),对照组不给任何钙剂。试验前后观测右足跟骨骨量,检验血清铁蛋白、钙。在试验前、试验1个月、3个月,6个月后检验尿钙。结果(1)成都市学龄前儿童膳食钙摄入量低,试验前血钙、尿钙水平低;补钙后试验组升至正常水平。(2)碳酸钙剂补充对跟骨骨量发育有促进作用。(3)补充钙剂6个月对血清铁蛋白无明显影响。结论钙补充对学龄前儿童的骨量提高有促进作用,对铁代谢无明显影响。学龄前儿童钙摄入少,建议每日补充300mg元素钙。     

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.     

饮用强化牛奶对青春期女生发育状况的影响研究

目的观察补充强化钙与维生素D的牛奶对青春期女生体格发育的影响,为促进青春期女生体格发育的研究提供依据。方法选取北京市9所小学498名女生(平均年龄10.1岁),分为对照组(保持日常饮食)、实验A组(除日常饮食外,饮用钙强化牛奶144 mL/d)和实验B组(除日常饮食外,饮用钙和维生素D强化牛奶144 mL/d),干预2 a及停止干预3 a后,进行追踪调查。结果干预2 a后,实验A组、实验B组学生身高、体重、骨密度增长值均明显高于对照组;停止干预3 a后,实验B组的身高、体重增长值明显低于对照组,实验A组身高、体重的增长值与对照组差异无统计学意义,且3组骨密度增长值均呈负增长。结论保证持续、充足的钙和维生素D摄入,有利于促进青春期女生的生长发育。     

儿童、青少年骨量发育状况

目的 了解儿童青少年时期骨量发育状况及特点。方法 采用单光子骨密度仪检测了161名健康9－20岁儿童青少年桡骨骨矿含量（BMC值）和骨密度（BMD值）。结果 男、女生骨量发育水平与年龄正相关,男生骨量发育在9－20岁期间呈显著持续增长,女生骨量增长则在16岁后出现减慢趋势;骨量发育与性发育关系密切,男、女生在17岁以后骨量水平已达峰值骨量（PBM）80％以上;体重对桡骨骨量水平作用不显著,青春期第三期（SMR3）以前骨量发育与线性生长关系密切。结论 整个性发育时期,男、女生骨量发育表现出不同特点,此期可积累PBM26％－39％,是骨量发育的关键时期;达到SMR3以前是一“身高关键期”,提示原发性骨质疏松症的预防工作应从儿童青少年时期开始。     

贵州水族男性青少年体格生长与性发育状况的调查及相关性分析

目的:了解贵州水族男性青少年体格生长和性发育的状况及其相关性,为水族地区开展青春期健康教育和中国男性生殖资源数据库的建立提供基础生理数据。方法:随机整群抽取贵州省三都县508名水族男性青少年进行体格生长及性发育情况测量,并采用概率单位回归法计算首次遗精年龄,分析体格发育与性发育的相关性。结果:贵州水族男性青少年的身高、体重在12岁进入生长加速,13岁进入身高增长高峰,体重发育比身高晚1年进入高峰期;青春期发育顺序是:睾丸、阴茎最先开始快速发育,身高、体重随后,阴毛和喉结较晚出现;半数首次遗精为13.31岁;性发育与体格发育的相关系数为0.42~0.62,两者呈中度正相关关系;同一年龄组中性发育分期越高,BMI值越大,Ⅱ期和Ⅲ期的BMI值比较有统计学差异(P<0.05)。结论:水族男性青少年的青春期发育符合一般儿童青少年生长发育规律,与其他地区比较,体格快速发育时间较晚,性发育开始成熟时间较早。     

补钙16个月对青春期男女生骨量的影响

目的探讨不同钙摄入量对我国青少年骨量的影响。方法对北京郊区337人(平均年龄为13.6岁)开展为期16个月的双盲对照干预研究,每天给予3次不同剂量碳酸钙片,每片含60IU维生素D,用双能X线吸收仪(DXA)测定全身、腰椎和前臂骨量。结果女生全身骨矿物密度的年增长率由低钙摄入组到高钙摄入组逐渐升高,调整混杂因素后差异消失。女生前臂远端1/3处和男生前臂远端1/10处的骨矿物含量年增长率和骨面积年增长率均以每天钙摄入900～1100mg/d的人群(平均钙摄入量984mg/d)最高,其中调整混杂因素后男生差异消失。结论青春期钙摄入量达到1000mg/d以上可促进青少年骨量增长,此结果有性别差异。     

Calcium supplementation provides an extended window of opportunity for bone mass accretion after menarche

BACKGROUND: High calcium intakes during adolescence may increase bone acquisition. The magnitude of the effect of dietary calcium supplementation and the timing of its administration to achieve significant effects on bone health are still incompletely defined. OBJECTIVE: The objective of this study was to assess the effect of calcium supplementation on bone mass accretion in postmenarcheal adolescent girls with low calcium intakes. DESIGN: A double-blind, placebo-controlled calcium supplementation study was implemented. One hundred girls with a mean (+/- SD) age of 14 +/- 0.5 y with habitual calcium intakes < 800 mg/d completed a 12-mo protocol. The treatment group received a daily supplement containing 1000 mg elemental calcium. Bone mineral density (BMD) and bone mineral content (BMC) of the total body, lumbar spine, and femoral neck were determined at inclusion, 6 mo, and 12 mo. Also measured were serum concentrations of biochemical markers of bone turnover (osteocalcin and deoxypyridinoline), parathyroid hormone, and vitamin D. RESULTS: The calcium-supplemented group had greater accretion of total-body BMD and lumbar spine BMD but not BMC than did the control group. Calcium supplementation appeared selectively beneficial for girls who were 2 y postmenarcheal. Calcium supplementation significantly decreased bone turnover and decreased serum parathyroid hormone concentrations. CONCLUSION: Calcium supplementation of postmenarcheal girls with low calcium intakes enhances bone mineral acquisition, especially in girls > 2 y past the onset of menarche.     

Effects of two years' milk supplementation on size-corrected bone mineral density of Chinese girls

Much existing data on the effects of calcium or milk products on bone mineral accretion are based on bone mineral content (BMC) or areal bone mineral density (aBMD), neither of which accounts for changing bone size during the growing period. The aim of this study was to investigate the effects of 2-year milk supplementation on total body size-corrected BMD in Chinese girls with low habitual dietary calcium intake. Chinese girls aged 10 years were randomised, according to their school, to receive calcium fortified milk (Ca milk), or calcium and vitamin D fortified milk (CaD milk) for two years or act as unsupplemented controls. Dual-energy X-ray absorptiometry total body bone measures were obtained from 345 girls at baseline and 2 years. Size-corrected total body and regional BMD was calculated as: BMDsc = BMC/BApc, where pc was the regression coefficient of the natural logarithm transformed total body BMC and bone area. After 2 years, both supplemented groups had significantly greater gain in BMDsc of total body (3.5-5.8%, p < 0.05) and legs (3.0-5.9%, p < 0.05) than did the control group. Milk supplementation showed positive effects on bone mineral accretion when accounting for the changing skeletal size during growth. The effects were mainly on the lower limbs.     

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.     

Nutrition influences skeletal development from childhood to adulthood: a study of hip, spine, and forearm in adolescent females

This study evaluated the long-term efficacy of supplemental calcium and dairy products on bone mineral areal density of the hip and spine and on the bone geometry and volumetric bone mineral density of the forearm in young females during late adolescence. The study was conducted among participants of a randomized double-blinded, placebo-controlled clinical trial with calcium supplements and among participants of an observational study with higher consumption of dairy products. Hip and spine measurements by dual-energy X-ray absorptiometry were done every 6 mo (dairy group every 12 mo) during last 3 y of the follow-up while peripheral quantitative computerized tomography of the forearm was done at the last visit. The results of the study show a positive influence of calcium supplementation and dairy products on bone mineral density of the hip and the forearm. Dairy products were also associated with a higher bone mineral density of the spine while calcium supplementation did not have an effect. Calcium exerts its action on bone accretion during growth primarily by influencing volumetric bone mineral density while milk may have an additional impact on bone growth and periosteal bone expansion.     

Calcium supplementation and bone mineral density in females from childhood to young adulthood: a randomized controlled trial

BACKGROUND: Short-term studies established that calcium influences bone accretion during growth. Whether long-term supplementation influences bone accretion in young adults is not known. OBJECTIVE: This study evaluated the long-term effects of calcium supplementation on bone accretion among females from childhood to young adulthood. DESIGN: A 4-y randomized clinical trial recruited 354 females in pubertal stage 2 and optionally was extended for an additional 3 y. The mean dietary calcium intake of the participants over 7 y was approximately 830 mg/d; calcium-supplemented persons received an additional approximately 670 mg/d. Primary outcome variables were distal and proximal radius bone mineral density (BMD), total-body BMD (TBBMD), and metacarpal cortical indexes. RESULTS: Multivariate analyses of the primary outcomes indicated that calcium-supplementation effects vary over time. Follow-up univariate analyses indicated that all primary outcomes were significantly larger in the supplemented group than in the placebo group at the year 4 endpoint. However, at the year 7 endpoint, this effect vanished for TBBMD and distal radius BMD. Longitudinal models for TBBMD and proximal radius BMD, according to the time since menarche, showed a highly significant effect of supplementation during the pubertal growth spurt and a diminishing effect thereafter. Post hoc stratifications by compliance-adjusted total calcium intake and by final stature or metacarpal total cross-sectional area showed that calcium effects depend on compliance and body frame. CONCLUSIONS: Calcium supplementation significantly influenced bone accretion in young females during the pubertal growth spurt. By young adulthood, significant effects remained at metacarpals and at the forearm of tall persons, which indicated that the calcium requirement for growth is associated with skeletal size. These results may be important for both primary prevention of osteoporosis and prevention of bone fragility fractures during growth.     

Effects of dairy food supplements on bone mineral density in teenage girls

Summary Background Bone mineral density (BMD) is largely genetically determined and this influence is most powerful in the period of rapid skeletal development in childhood and late adolescence but environmental factors such as exercise and dietary calcium intake may influence up to 20%. Aims of the study The aims of the study were to examine healthy late adolescent females for the effects and benefits of a high calcium intake from dairy product foods on bone mineral density, body composition, lipids and biochemistry. The secondary aim is determine whether a high intake of dairy product foods in the diet is acceptable for this age group long term. Methods Ninety-one teenage girls who participated in a two-year randomised controlled study on the effect of dairy food supplementation on dietary patterns, body composition and bone density in post-pubertal teenage girls were approached one year after the cessation of the study to determine the effects of the cessation of dairy supplements on bone mineral density, dietary habits, biochemical markers, body composition and blood lipids. Bone mineral density and bone mineral content were assessed at the hip, spine and total body. Anthropometric data were collected, and exercise, Tanner, dietary assessment, preference and compliance questionnaires were administered. Lipid profiles, hydroxyproline excretion and urinary calcium and sodium excretion measurements were performed. Results There were no significant differences between the 2 groups for height, weight, lean and fat mass. The supplemented group had significantly higher calcium, phosphorus and protein intake during the supplementation period (p<0.001). No differences were seen between the groups 12 months after supplementation finished. There were no significant differences in exercise level, preference or acceptability of dairy products or in the lipids and bone markers between baseline the end of supplementation and 1 year follow-up. There was a significant increase in trochanter (4.6%), lumbar spine (1.5%) and femoral neck (4.8%) BMD (p<0.05) in the high calcium group at the end of supplementation. There was an increase in bone mineral content at the trochanter (p<0.05) and lumbar spine; however the latter was not statistically significant, in the high calcium group at the end of supplementation. There was no difference in vertebral height or width at any stage of the study, indicating no influence on bone size. Conclusions In this 3 year study (2 years of supplementation, 1 year follow-up), teenage girls, aged 15–18 years, were able to significantly increase their BMD at the trochanter, femoral neck and lumbar spine when supplemented with dairy product foods to a mean calcium intake of 1160 mg/d. There was also an effect seen on the BMC particularly at the trochanter and to a lesser extent at the lumbar spine. The dietary calcium intake achieved did not adversely affect body weight, fat and lean mass or blood lipid profiles. Twelve months after the supplementation finished the girls had returned to their baseline diet, indicating self-selection of a high dairy product diet may be hard to achieve. Received: 5 June 2000, Accepted: 5 September 2000     

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.     

Effects of increased dietary calcium intake upon the calcium and bone mineral status of lactating adolescent and adult women

We studied the effectiveness of an increased calcium (Ca) diet in preventing bone mineral loss in lactating adolescent mothers. Three groups of lactating women were studied: 15 control adolescents consuming their usual Ca diet (900 mg/d), 21 experimental adolescents consuming a high-Ca diet (greater than 1600 mg/d), and 12 adults. At 2 and 16 wk postpartum, serum calcium, phosphate, magnesium, albumin, alkaline phosphatase, vitamin D, parathyroid hormone (PTH), and calcitonin (CT) were determined. Bone mineral analyses were performed by photon absorptiometry. By 16 wk the control adolescent group had a 10% decrease in bone mineral content (BMC) and increased PTH and CT. The experimental adolescent and adult groups had no significant change in BMC during the study. There was a positive correlation (r = 0.45, p less than 0.01) between dietary Ca intake and BMC in all adolescents. Data suggest that bone loss during lactation in adolescents may be prevented with adequate dietary Ca intakes.