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.     

Effect of withdrawal of calcium and vitamin D supplements on bone mass in elderly men and women

BACKGROUND: Supplementation with calcium and vitamin D reduces bone loss and prevents fractures in elderly people, but it is not known whether any lasting benefit remains if the supplements are discontinued. OBJECTIVE: The objective was to determine whether gains in bone mineral density (BMD) induced by calcium and vitamin D supplementation persist after supplement withdrawal. DESIGN: Two-hundred ninety-five healthy, elderly men and women (aged >/=68 y) who had completed a 3-y randomized, placebo-controlled trial of calcium and vitamin D supplementation were followed for an additional 2 y during which no study supplements were given. BMD was measured by dual-energy X-ray absorptiometry, and biochemical variables related to calcium metabolism and bone turnover were measured. RESULTS: In the 128 men, supplement-induced increases in spinal and femoral neck BMD were lost within 2 y of supplement discontinuation, but small benefits in total-body BMD remained. In the 167 women, there were no lasting benefits in total-body BMD or at any bone site. Consistent with the observations on BMD, the bone turnover rates in both men and women (as measured by serum osteocalcin concentrations) returned to their original higher concentrations within the same 2-y period. CONCLUSION: Discontinued calcium and vitamin D supplementation has limited cumulative effect on bone mass in men and women aged >/=68 y.     

雌激素受体基因XbaI多态性与补钙对青春期少女骨骼发育作用的关系

目的研究雌激素受体(ER)基因XbaI多态性与补钙对青春期少女骨骼发育作用的关系,为制定钙膳食参考摄入量提供科学依据。方法从志愿者中选取88名13~15岁青春期少女,随机分为补钙组和对照组,并按XbaI多态性分成不同的亚组,进行为期1年的补钙实验。在补钙前后测定全身各部位骨密度、骨钙素(BGP)、骨碱性磷酸酶(BAP)、抗酒石酸酸性磷酸酶(TRACP)、雌二醇(E2)及维生素D水平。比较不同基因亚型间补钙后骨密度增长或骨生化指标变化的差异。结果共72人完成了整个研究。经过1年的干预,补钙组BGP的增长及前臂远端1/10处的骨密度增长均大于对照组;补钙组内的Xx亚型反映骨形成的指标BAP的增长大于xx亚型,且全身各测量部位的骨密度增长值均大于xx亚型,但无显著性差异;而对照组内各XbaI亚型上述各指标的增长值未见统计学差异。结论XbaI多态性中Xx较xx亚型具有更好的补钙反应性,在今后的补钙干预中应考虑该遗传因素的影响。     

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.     

Vitamin K, bone turnover, and bone mass in girls

BACKGROUND: Vitamin K has been suggested to have a role in bone metabolism, and low vitamin K intake has been related to low bone density and increased risk of osteoporotic fracture. OBJECTIVE: The objective of this study was to determine whether phylloquinone (vitamin K(1)) intake and biochemical indicators of vitamin K status are related to bone mineral content (BMC) and markers of bone formation and bone resorption in girls. DESIGN: Vitamin K status [plasma phylloquinone concentration and percentage of undercarboxylated osteocalcin (%ucOC)] was measured at baseline in a study of 245 healthy girls aged 3-16 y. Cross-linked N-telopeptide of type 1 collagen (NTx) breakdown, osteocalcin, and bone-specific alkaline phosphatase were measured to reflect bone resorption and formation. BMC of the total body, lumbar spine, and hip and dietary phylloquinone intake were measured annually for 4 y. RESULTS: Phylloquinone intake (median: 45 microg/d) was not consistently associated with bone turnover markers or BMC. Better vitamin K status (high plasma phylloquinone and low %ucOC) was associated with lower bone resorption and formation. Plasma phylloquinone was inversely associated with NTx and osteocalcin concentrations (P < 0.05), and %ucOC was positively associated with NTx and bone-specific alkaline phosphatase concentrations (P < 0.05). Indicators of vitamin K status were not consistently associated with current BMC or gain in BMC over the 4-y study period. CONCLUSIONS: Better vitamin K status was associated with decreased bone turnover in healthy girls consuming a typical US diet. Randomized phylloquinone supplementation trials are needed to further understand the potential benefits of phylloquinone on bone acquisition in growing children.     

Effect of cyclical intravenous clodronate therapy on bone mineral density and markers of bone turnover in patients receiving home parenteral nutrition

BACKGROUND: Patients receiving home parenteral nutrition (HPN) because of intestinal failure are at high risk of developing osteoporosis. OBJECTIVE: We studied the effect of the bisphosphonate clodronate on bone mineral density (BMD) and markers of bone turnover in HPN patients. DESIGN: A 12-mo, double-blind, randomized, placebo-controlled trial was conducted to study the effect of 1500 mg clodronate, given intravenously every 3 mo for 1 y, in 20 HPN patients with a bone mass T score of the hip or lumbar spine of less than -1. The main outcome measure was the difference in the mean percentage change in the BMD of the lumbar spine measured by dual-energy X-ray absorptiometry. Secondary outcome measures included changes in the BMD of the hip, forearm, and total body and biochemical markers of bone turnover, ie, serum osteocalcin, urinary pyridinoline, and urinary deoxypyridinoline. RESULTS: The mean (+/-SEM) BMD of the lumbar spine increased by 0.8 +/- 2.0% in the clodronate group and decreased by 1.6 +/- 2.0% in the placebo group (P = 0.43). At all secondary skeletal sites (ie, hip, total body, and distal forearm), we observed no changes or small increases in the BMD of the clodronate group and decreases in the BMD of the placebo group. In the clodronate group, biochemical markers of bone resorption decreased significantly (P < 0.05). CONCLUSIONS: Clodronate significantly inhibits bone resorption as assessed by changes in biochemical markers of bone turnover. Although the mean BMD increased in the clodronate group, cyclic clodronate therapy failed to increase spinal BMD significantly at 12 mo.     

Bone mineral contents and plasma osteocalcin concentrations of Gambian children 12 and 24 mo after the withdrawal of a calcium supplement

BACKGROUND: Our randomized, placebo-controlled supplementation study of 160 rural Gambian children aged 8.3-11.9 y showed that an increase in calcium intake of 714 mg/d for 12 mo resulted in a 5% increase in forearm bone mineral acquisition and a 22% decrease in plasma osteocalcin concentration, a bone formation marker, but had no effect on height or bone dimensions. OBJECTIVE: We investigated whether these results were sustained after supplement withdrawal. DESIGN: All participants were followed up 12 (FU1) and 24 (FU2) mo after supplementation ended. 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. Plasma osteocalcin concentration was measured at FU1. RESULTS: At follow-up, the calcium group had greater bone mineral status than did the placebo group at the midshaft radius (mean difference +/- SE), FU1: BMC (4.7 +/- 1.6%; P = 0.004), BMD (5.1 +/- 1.1%; P 相似文献   

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.     

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。     

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   

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。     

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。     

老年骨质疏松患者服用钙加维生素D后骨密度及生化指标的改变

目的了解补充钙和维生素D对骨丢失和骨转换的影响。方法对31例门诊原发性骨质疏松症和骨量减少患每日服用1片碳酸钙和维生素D复合剂(每片含元素钙600mg和维生素D125IU),连服6个月。治疗前后检测腰椎骨密度(BMD)、骨矿含量(BMC)及骨转换生化指标。结果碳酸钙和维生素D复合剂每日1片能明显改善骨质疏松引起的腰背疼和腿痛性痉挛,有明显疗效。可以维持腰椎骨密度,明显增加男性腰椎骨矿含量( 2．7％),与治疗前比较,明显提高血清250HD( 13．8％)和BGP(％29．5％),减少尿HOP／Cr比值(-17．5％)。结论老年人每天1片碳酸钙和维生素D复合剂对防止骨丢失,改善维生素D的营养状态,促进骨形成和抑制骨吸收有一定作用。     

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     

The skeletal benefits of calcium- and vitamin D3-fortified milk are sustained in older men after withdrawal of supplementation: an 18-mo follow-up study

BACKGROUND: In a previous 2-y randomized controlled trial, we showed that calcium- and vitamin D3-fortified milk stopped or slowed bone loss at several clinically relevant skeletal sites in older men. OBJECTIVE: The present study aimed to determine whether the skeletal benefits of the fortified milk were sustained after withdrawal of the supplementation. DESIGN: One hundred nine men >50 y old who had completed a 2-y fortified milk trial were followed for an additional 18 mo, during which no fortified milk was provided. Bone mineral density (BMD) of the total hip, femoral neck, lumbar spine, and forearm was measured by using dual-energy X-ray absorptiometry. RESULTS: Comparison of the mean changes from baseline between the groups (adjusted for baseline age, BMD, total calcium intake, and change in weight) showed that the net beneficial effects of fortified milk on femoral neck and ultradistal radius BMD at the end of the intervention (1.8% and 1.5%, respectively; P < 0.01 for both) were sustained at 18-mo follow-up (P < 0.05 for both). The nonsignificant between-group differences at the total hip (0.8%; P = 0.17) also persisted at follow-up (0.7%; P = 0.10), but there were no lasting benefits at the lumbar spine. The average total dietary calcium intake in the milk supplementation group at follow-up approximated recommended amounts for Australian men >50 y old (1000 mg/d) but did not differ significantly from that in the control subjects (1021 versus 890 mg/d). CONCLUSION: Supplementation with calcium- and vitamin D3-fortified milk for 2 y may provide some sustained benefits for BMD in older men after withdrawal of supplementation.     

Bone and gastric bypass surgery: effects of dietary calcium and vitamin D

OBJECTIVE: To examine bone mass and metabolism in women who had previously undergone Roux-en-Y gastric bypass (RYGB) and determine the effect of supplementation with calcium (Ca) and vitamin D. RESEARCH METHODS AND PROCEDURES: Bone mineral density and bone mineral content (BMC) were examined in 44 RYGB women (> or = 3 years post-surgery; 31% weight loss; BMI, 34 kg/m(2)) and compared with age- and weight-matched control (CNT) women (n = 65). In a separate analysis, RYGB women who presented with low bone mass (n = 13) were supplemented to a total 1.2 g Ca/d and 8 microg vitamin D/d over 6 months and compared with an unsupplemented CNT group (n = 13). Bone mass and turnover and serum parathyroid hormone (PTH) and 25-hydroxyvitamin D were measured. RESULTS: Bone mass did not differ between premenopausal RYGB and CNT women (42 +/- 5 years), whereas postmenopausal RYGB women (55 +/- 7 years) had higher bone mineral density and BMC at the lumbar spine and lower BMC at the femoral neck. Before and after dietary supplementation, bone mass was similar, and serum PTH and markers of bone resorption were higher (p < 0.001) in RYGB compared with CNT women and did not change significantly after supplementation. DISCUSSION: Postmenopausal RYGB women show evidence of secondary hyperparathyroidism, elevated bone resorption, and patterns of bone loss (reduced femoral neck and higher lumbar spine) similar to other subjects with hyperparathyroidism. Although a modest increase in Ca or vitamin D does not suppress PTH or bone resorption, it is possible that greater dietary supplementation may be beneficial.     

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     

Effect of a calcium and exercise intervention on the bone mineral status of 16-18-y-old adolescent girls

BACKGROUND: Osteoporosis may be prevented or delayed by maximizing peak bone mass through diet modification and physical activity during adolescence. OBJECTIVE: We studied whether increases in calcium intake and physical activity effectively increase the bone mineral status of adolescent girls aged 16-18 y. DESIGN: We conducted a 15.5-mo study of calcium supplementation (1000 mg Ca/d as carbonate) in 144 adolescent girls aged 17.3 +/- 0.3 y ( +/- SD). The subjects were randomly allocated to an exercise (three 45-min exercise-to-music classes/wk during term time) or nonexercise group. Dual-energy X-ray absorptiometry of the whole body, spine, forearm, and hip was performed before and after intervention. RESULTS: The mean (+/- SD) percentage of subjects compliant with supplement taking was 70 +/- 27% and with exercise class attendance was 36 +/- 25%. Baseline calcium intake was 938 +/- 411 mg/d. Calcium supplementation significantly increased size-adjusted bone mineral content. The effect was stronger in subjects with good compliance (percentage difference +/- SE): whole body, 0.8 +/- 0.3% (P < or = 0.01); lumbar spine, 1.9 +/- 0.5% (P < or = 0.001); ultradistal radius, 1.3 +/- 0.6% (P < or = 0.05); total hip, 2.7 +/- 0.6% (P < or = 0.001); femoral neck, 2.2 +/- 0.7% (P < or = 0.001); trochanter, 4.8 +/- 0.9% (P < or = 0.001). Attendance at > 50% of the exercise sessions was significant at the total hip (1.4 +/- 0.7%; P < or = 0.05) and trochanter (2.6 +/- 1.2%; P < or = 0.05). CONCLUSIONS: Calcium supplementation and exercise enhanced bone mineral status in adolescent girls. Whether this is a lasting benefit, leading to the optimization of peak bone mass and a reduction in fracture risk, needs to be determined.     

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 taurine supplementation on bone mineral density in ovariectomized rats fed calcium deficient diet

Taurine supplementation has been shown to have a beneficial effect on femur bone mineral content in ovariectomized rats. It therefore seemed desirable to find out whether the beneficial effect of taurine on ovariectomized rats fed calcium deficient diet could also be reproduced. Forty female Sprague-Dawley rats were divided into two groups. One group was OVX and the other group received sham operation (SHAM), and received either control diet or a taurine supplemented diet for 6 weeks. All rats were fed on calcium deficient diet (AIN-93: 50% level of calcium) and deionized water. Bone mineral density (BMD) and bone mineral content (BMC) were measured in spine and femur. The serum and urine concentrations of calcium and phosphorus were determined. Bone formation was measured by serum osteocalcin and alkaline phosphatase (ALP) concentrations. Bone resorption rate was measured by deoxypyridinoline (DPD) crosslinks immunoassay and corrected for creatinine. Urinary calcium and phosphorus excretion, osteocalcin in blood and cross link value were not significantly different among the groups. Within the OVX group, the taurine supplemented group had not higher femur bone mineral content than the control group. This study established the need for a study on the taurine effect on bone with different calcium levels.