膳食钙摄入量与青春前期女童骨量关系的研究

目的:研究青春前期女童膳食钙摄入量与骨量的关系,为指导合理钙营养提供科学依据。方法:采用双能X线骨密度测量仪测量年龄在10±1岁的194名青春前期女童全身及多位点骨密度和骨矿物质含量,采用食物频数及3d膳食询问法调查膳食钙摄入量,问卷法调查体力活动。结果:日均钙摄入量与所测各位点骨矿物质含量及骨密度均呈显著正相关;日均钙摄入量平均从257mg增加到759mg,不同位点的骨矿物质含量和骨密度分别增加13%～22%和3.6%～16%。结论:增加青春前期女童膳食钙摄入量有助于获得较高骨量和骨密度。     

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.     

甲状旁腺激素基因多态性与钙摄入量对青春期女童骨量增长的交互作用

目的:探讨甲状旁腺激素(PTH)基因多态性与钙摄入量对青春期女童骨量增长的交互作用。方法:选择228名9～11.5岁未月经初潮的健康女童进行2年追踪,用双能X线骨密度仪(DEXA)检测对象追踪前后全身、左侧近端股骨(包括股骨颈、大转子、粗隆间和华氏三角区)、L1～L4腰椎骨矿含量和骨密度,采用PCR-RFLP技术检测PTH基因BstBⅠ位点多态性。结果:BB基因型女童L1～L4腰椎骨矿含量增长率、左侧近端股骨、粗隆间和L1-L4腰椎骨密度增长率均高于含b等位基因女童(P=0.022～0.047)。BB基因型女童在高钙摄入(>950mg/d)时,粗隆间骨矿含量(ITBMC)增长率较中等和低钙摄入时分别高29.4%和35.0%,股骨颈骨密度(FNBMD)增长率分别高66.7%和46.2%。而含b等位基因女童的ITBMC和FNBMD增长率在不同钙摄入量之间没有显著性差异。结论:PTH基因BstBⅠ多态性与钙摄入量对青春期女童骨量增长存在交互作用,BB基因型女童高钙摄入可促进其骨量增长。     

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。     

Parathyroid hormone is elevated but bone markers and density are normal in young female subjects who consume inadequate dietary calcium

Dietary Ca and osteocalcin (OC), parathyroid hormone (PTH), 25-hydroxyvitamin D (25-OH-D), insulin-like growth factor (IGF)-I and sex hormone binding globulin (SHBG) were assessed simultaneously to bone mineral density (BMD) in 200 adolescent girls (aged 11-15 years) and 100 young women (aged 20-23 years), selected from the lowest and highest end of the Ca intake distribution of a larger population sample. Ca intake was evaluated by food frequency questionnaires, BMD was measured by dual energy x-ray absorptiometry at ultradistal and proximal radius of non-dominant arm, bone age was estimated from x-rays of left hand and wrist according to Tanner et al. (1983). Surprisingly, mean Ca intakes were below the dietary reference intakes in the subgroups of girls and women with the highest measured Ca consumption. Postmenarcheal, but not premenarcheal girls showed radial densities as high as the women and in no group was BMD associated with Ca intake. In all adolescents serum PTH was negatively related to dietary Ca. In girls before menarche IGF-I was positively associated with bone age, while in the same subjects the negative relationship between SHBG and BMD pointed to the crucial role of bioavailable sex steroids on bone mass apposition in early puberty. OC levels decreased progressively with age, while serum 25-OH-D significantly increased after menarche. In conclusion, although in adolescents low Ca intake has not been shown to induce any immediate deleterious effect on radial density, the compensatory hypersecretion of PTH supports the need for an adequate Ca intake to achieve peak bone mass.     

The effect of dietary calcium intake on bone mineral density in healthy adolescent girls and young women in southern Italy.

BACKGROUND: The association between forearm bone mineral areal density (BMD) and dietary calcium, anthropometric characteristics, puberty, and physical activity was studied for the first time in 200 girls (aged 11-15 years) and 100 women (aged 20-23 years) living in Southern Italy. METHODS: The BMD was assessed by dual energy x-ray absorptiometry at ultradistal (ud) and proximal (pr) radial sites and dietary calcium was evaluated using Food Frequency Questionnaires and detailed 3-day food records. RESULTS: For population samples grouped according to low and high calcium intake levels, forearm densities were quite similar among both girls and women. Independently of calcium intake, girls displayed strong correlations between ud/pr-BMD and age, bone age, weight, height and BMI. Furthermore, in girls of similar age and BMI, radial densities were substantially increased following menarche. Positive relationships between weight, BMI and both ud/pr-BMD were only evident in women with high calcium intake. CONCLUSIONS: This study showed that different calcium intake values do not appear to affect forearm mineral densities at the ages investigated, however puberty represents the major event in radial bone mass acquisition during adolescence.     

膳食钙不足对香港青少年先天性脊柱侧凸全身骨质密度偏低的影响(英文)

青少年先天性脊柱侧凸 (AIS)是一种主要影响女孩的脊柱严重三维畸形病。在香港有 3 %～ 4%的发病率 ,AIS的病人同时发现患有全身性的骨密度偏低现象。本文试图研究是否低骨矿物质密度 (BMD)与AIS病人钙摄入量有关。以 11～ 16岁 582名AIS患者和 2 0 6名健康对照人群为研究对象。面积骨矿物质密度 (aBMD)和体积骨矿物质密度 (vBMD)分别用DXA(Norland XR 3 6)和PQCT(Densiscan 10 0 0 )检测。钙和其它营养素摄入量用食物频率法评价。受试者钙绝对摄入量低 (<50 0mg d)。患AIS少女平均钙摄入量显著高于对照组少女 [(441± 3 4 4 )mg dvs.(3 90± 2 81)mg d ,P =0 0 15] ,11～ 16岁AIS患者大多数骨骼测定点BMD显著低于同龄对照组 (P≤ 0 0 5)。AIS患者与对照组BMD的差异程度随着年龄的增长而增加。 15～ 16岁年龄组AIS患者中钙摄入量与在大多数骨骼测定点测得的BMD有显著相关性 ,而在对照组中没有发现这种相关性。经多因素分析 ,在控制干扰变量的情况下 ,预测BMD的变化 ,钙摄入量是一个非依从性决定因素。结果提示 ,AIS患者绝对钙摄入量低 ,在各年龄组青少年中各个骨骼测定点测得的BMD ,AIS患者组均低于对照组。只有在AIS患者中钙摄入量与BMD有相关性 ,而健康的对照中没有相关性。这表明钙摄入量对AIS患者     

Dietary iron is associated with bone mineral density in healthy postmenopausal women

Healthy nonsmoking postmenopausal women (n = 242; ages 40-66 y) were included in the Bone, Estrogen, and Strength Training (BEST) Study. Bone mineral density (BMD) was measured at five sites (lumbar spine L2-L4, trochanter, femur neck, Ward's triangle and total body) using dual energy X-ray absorptiometry (DXA). Mean nutrient intakes were assessed using a 3-d diet record. Regression models were calculated using each BMD site as the dependent variable and iron as the independent variable. Covariates included in the models were years past menopause, fat-free mass, fat mass, use of hormone replacement therapy, total energy intake and dietary intake of protein and calcium. Using linear models, iron was associated with greater BMD at all sites (P < or = 0.01), even after adjusting for protein and/or calcium. Increasing levels of iron intake (>20 mg) were associated with greater BMD at several bone sites among women with a mean calcium intake of 800-1200 mg/d. Elevated iron intake was not associated with greater BMD among women with higher (>1200 mg/d) or lower calcium intakes (<800 mg/d). Dietary iron may be a more important factor in bone mineralization than originally thought and, its combined effect with calcium on BMD warrants exploration in future studies.     

Sustained effect of short-term calcium supplementation on bone mass in adolescent girls with low calcium intake

BACKGROUND: The effect of short-term calcium supplementation on peak bone mass in adolescent girls is not completely defined. In our previous double-blind, placebo-controlled, calcium-supplementation study (1000 mg calcium carbonate/d), we showed that calcium supplementation of postmenarcheal girls with low calcium intakes enhances bone mineral acquisition. OBJECTIVE: The objective of this follow-up study, conducted 3.5 y after the end of calcium supplementation, was to investigate the sustained effect of calcium supplementation on bone mineral mass. DESIGN: Anthropometric data, nutrient intakes, and bone variables were reassessed in 96 of the 100 adolescent girls whose data had been studied at the end of the supplementation period. Bone mineral content and bone mineral density (BMD) of the total body, lumbar spine, and femoral neck were determined by dual-energy X-ray absorptiometry. RESULTS: The calcium-supplemented group tended to have a greater accretion of total-body BMD (TBBMD) than did the control group 3.5 y after the end of supplementation. The finding was statistically significant in the active-treatment cohort (n = 17 in the calcium-supplemented group and 28 in the placebo group), who had a compliance rate of > or =75% during the intervention study. In a multivariate linear-regression analysis, TBBMD accretion from the beginning of the intervention study to the follow-up study in the active-treatment cohort was attributed to calcium supplementation and to the time since inclusion in the initial study. CONCLUSION: Calcium supplementation for 1 y in postmenarcheal girls with low calcium intakes may provide a sustained effect on the basis of TBBMD measurements in participants with compliance rates of > or =75%.     

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     

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.     

Effect of calcium supplementation on bone mineral accretion in gambian children accustomed to a low-calcium diet

BACKGROUND: Rural Gambian children have poor growth, delayed puberty, a low bone mineral content, and a low calcium intake. OBJECTIVE: We investigated the effect of a calcium supplement on bone mineral accretion in rural Gambian children. DESIGN: A randomized, double-blind, placebo-controlled study was conducted in 160 children (80 boys, 80 girls) aged 8.3-11.9 y. Bone mineral content (BMC), bone mineral density (BMD), and BMC adjusted for bone width, body weight, and height (size-adjusted BMC) were measured at the midshaft and distal radius. Each child received either 1000 mg Ca/d (as calcium carbonate) or a placebo 5 d/wk for 12 mo. Supplementation increased calcium intake from 342 to 1056 mg/d (8.6 to 26.4 mmol/d). RESULTS: Calcium supplementation resulted in a higher BMC, BMD, and size-adjusted BMC (&xmacr; difference +/- SE): midshaft radius-BMC (3.0 +/- 1.4%; P = 0.034), BMD (4.5 +/- 0.9%; P 相似文献   

Effect of Calcium Supplementation Is Greater in Prepubertal Girls with Low Calcium Intake

In a recent calcium supplementation trial, prepubertal girls with spontaneous calcium intake below 900 mg/day, when given additional calcium, had greater increases in bone mineral density than other girls. This lends support to the recently recommended Adequate Intake (AI) of 1300 mg/day calcium for American and Canadian children, although more studies on long-term effects of this intake level are still needed.     

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 does not augment bone gain in young women consuming diets moderately low in calcium

In earlier observational work, the dietary calcium:protein ratio was directly related to bone accrual in healthy postadolescent women. In this study, we sought to test the hypothesis that augmented calcium intake would increase postadolescent skeletal consolidation, using a double-blind, randomized, placebo-controlled design. We recruited 152 healthy young women (age 23.1 +/- 2.7 y, BMI 22.5 +/- 3.0 kg/m2); their usual diets, as assessed by 7-d food diaries, were low in calcium (605 +/- 181 mg/d; 15.1 +/- 4.5 mmol/d) and in the calcium:protein ratio (10.1 +/- 2.0 mg/g). The subjects were randomly assigned to supplemental calcium [500 mg calcium (12.5 mmol) as the carbonate, 3 times/d, with meals] or placebo capsules identical in appearance; all participants also took a daily multivitamin, and they were followed for up to 36 mo with bone densitometry (dual energy X-ray absorptiometry; DXA) at 6-mo intervals. A total of 121 subjects remained in the study for at least 12 mo (median time in the study, 35 mo), with a mean compliance level (observed/expected tablet consumption) of 87.7%. DXA data for these 121 subjects indicated modest but significant mean rates of increase (i.e., 0.24 to 1.10%/y) in bone mineral content (BMC; total body, total hip, and lumbar spine) and in lumbar spine bone mineral density (BMD) but no change in total hip BMD. None of these rates of change differed by group, i.e., calcium supplementation did not have any measurable effect on bone mass accrual. By midstudy, the calcium content of the subjects' usual diets for both groups had risen by approximately 15%. The combined effect of improved intakes of dietary calcium and the small amount of calcium added by the multivitamin tablets resulted in a mean calcium intake for the control group > 800 mg (20 mmol)/d, possibly at or near the threshold beyond which additional calcium has no further effect on bone accrual.     

Is caffeine associated with bone mineral density in young adult women?

BACKGROUND: By increasing the urinary excretion of calcium, caffeine consumption may reduce bone mineral density (BMD) and subsequently increase the risk for osteoporotic fracture. Although negative associations between caffeine consumption and BMD have been reported for postmenopausal women, in particular for those who consume low amounts of dietary calcium, the relation between caffeine and BMD in younger women is unclear. Therefore, we evaluated the association between caffeine consumption and BMD in a cross-sectional study of 177 healthy white women, age 19-26 years, who attended a Midwestern university. METHODS: Average caffeine intake (milligrams per day) was calculated from self-reports of the consumption of coffee, decaffeinated coffee, tea, colas, chocolate products, and select medications during the previous 12 months (mean caffeine intake = 99. 9 mg/day). BMD (grams per square centimeter) at the femoral neck and the lumbar spine was measured by dual-energy X-ray absorptiometry. RESULTS: After adjusting in linear regression models for potential confounders, including height, body mass index, age at menarche, calcium intake, protein consumption, alcohol consumption, and tobacco use, caffeine consumption was not a significant predictor of BMD. For every 100 mg of caffeine consumed, femoral neck BMD decreased 0.0069 g/cm(2) (95% confidence in terval [CI] = -0.0215, 0. 0076) and lumbar spine BMD decreased 0.0119 g/cm(2) (95% CI = -0. 0271, 0.0033). No single source of caffeine was significantly associated with a decrease in BMD. Furthermore, the association between caffeine consumption and BMD at either site did not differ significantly between those who consumed low levels of calcium (< or =836 mg/day) and those who consumed high levels of calcium (>836 mg/day). CONCLUSIONS: Caffeine intake in the range consumed by young adult women is not an important risk factor for low BMD.     

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。     

不同钙摄入量对青年男性骨密度的影响

目的 探讨不同钙摄入量对我国青年男性骨密度的影响，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个月的双盲对照干预研究。将某军校男学员155人，平均年龄21．3岁，随机分为4组，以干预前全身骨密度及膳食钙摄入量为基线，进行不同剂量碳酸钙片营养干预，使总钙摄入量分别达到约500、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，双能X线骨密度仪（DEXA）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514mg／d（1组）、821mg／d（2组）、987mg／d（3组）、1209mg／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，第2、3、4组全身、前臂、骨盆的骨密度增加值显著高于第1组，且三组之间无显著性差异；第3、4组下肢骨密度增加值显著高于第1、2组，且3、4组之间无显著性差异。结论 随着钙摄入量的增加，青年男性全身各部位骨密度增加，当钙摄入量达到约1000mg／d时，全身、前臂、骨盆和下肢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。提示我国青年男性钙的适宜摄入量可能在1000mg／d左右。     

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.     

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.