Reliability and validity of a brief questionnaire to assess calcium intake in female collegiate athletes

Calcium intake often is inadequate in female collegiate athletes, increasing the risk for training injuries and future osteoporosis. Thus, a brief and accurate assessment tool to quickly measure calcium intake in athletes is needed. We evaluated the reliability and validity, compared to 6 days of diet records (DRs), of the Rapid Assessment Method (RAM), a self-administered calcium checklist. Seventy-six female collegiate athletes (mean age = 18.8 yrs, range= 17- 21; 97 % Caucasian) were recruited from basketball, cross-country, field hockey, soccer, and volleyball teams. Athletes completed a RAM at the start of the training season to assess calcium intake during the past week. Two weeks later, a second RAM was completed to assess reliability, and athletes began 6 days of diet records (DRs) collection. At completion of DRs, athletes completed a final RAM, corresponding to the same time period as DRs, to assess agreement between the 2 instruments. The RAM demonstrated adequate test-retest reliability over 2 weeks (n= 56; Intraclass correlation [ICC] = 0.54, p < 0.0001) and adequate agreement with DRs (n = 34; ICC = 0.41, p = 0.0067). Calcium intake was below recommended levels, and mean estimates did not differ significantly on the RAM (823 +/- 387 mg/d) and DRs (822 +/- 330 mg/d; p = 0.988). Adequacy of calcium intake from both DRs and the RAM was classified as "inadequate" (<1000 mg/d) and "adequate" (> or = 1000 mg/d). Agreement between the RAM and DRs for adequacy classification was fair (ICC= 0.30, p = 0.042), with the RAM identifying 84% of athletes judged to have inadequate calcium intake based on DRs. The RAM briefly and accurately estimates calcium intake in female collegiate athletes compared to DRs.     

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   

Bone mineral density in young active females: the case of dancers

The aim of the study was to evaluate the combined effect of several environmental factors on bone mineral density (BMD) in a group of highly active young women. Body composition, total body and regional (arms, legs and trunk) BMD, dietary intake, menstrual status, training habits, and eating attitudes were assessed in 37 professional dance students, aged 18 to 26 years. Dancers had higher BMD values compared to age- and weight-matched reference population (mean total body BMD: 1.185 g/cm2, 9% higher than reference values). No differences were detected between currently eumenorrheic and noneumenorrheic dancers; subjects who encountered menstrual problems during adolescence had significantly lower BMD values compared to counterparts who did not. Regarding dietary intake, dancers in the highest quartile of calcium intake (1323 +/-113 mg/d) exhibited significantly higher total BMD values than subjects in the other 3 quartiles (p =.04). A moderate inverse relationship was found between protein intake and total BMD, after controlling for energy and calcium intake (r = - 0.37). Fat-free soft mass was the only significant predictor of total BMD, explaining 20% of the variance. High levels of calcium intake were associated with high total BMD values. These results confirm the beneficial role of long-term and intensive physical activity on BMD and further suggest that dancers are not at a greater risk compared to the general population for developing osteoporosis, despite their menstrual and eating problems.     

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。     

One year of oral calcium supplementation maintains cortical bone density in young adult female distance runners

We conducted a double-blind, placebo-controlled, randomized trial to determine whether 1 year of supplemental calcium intake would augment hip [greater trochanter, GT, femoral neck (FN), total hip (TH)], spine (LS), and femoral mid-shaft (Fmr) BMD in female distance runners. Twenty-three women (age: 23.7 +/- 4.7 yrs, height: 165.6 +/- 6.3 cm, weight: 55.7 +/- 6.1 kg) were randomly assigned to receive either 1000 mg/d of supplemental calcium (N = 13) or placebo tablets (N = 10) for 1 year. BMD was determined by DXA (Hologic 1000-W) and tablet compliance by self-report logs. Compliance averaged 79% and 71% for supplement and placebo groups, respectively. Calcium supplementation did not affect hip or spine BMD, but did prevent loss at the femoral mid-shaft (GT: -0.5% vs. 0.2%, FN: 0.9% vs. 1.1%, TH: -0.3% vs. 0.2%, LS: 0.3% vs. 1.2%, Fmr: 0.1% vs. -1.8%, for calcium vs. placebo, respectively). We conclude that the addition of 800 mg/d of supplemental calcium to the diet of young adult female distance runners with habitual calcium intakes of approximately 1000 mg/d, prevents cortical but not trabecular bone loss.     

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.     

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.     

孕期钙摄入量对孕产妇骨密度的影响

目的　研究孕期不同钙摄入量对产妇骨密度的影响。方法　对３５ 名２４ ～３１ 岁、孕１８周第１ 胎的健康妇女从孕２０ 周至产后４５ 天进行追踪研究, 以营养软件指导膳食,在热能和其他营养素摄入基本一致下,按钙摄入量分为Ⅰ、Ⅱ、Ⅲ组,钙摄入量分别为（５５０ ±１５０） ｍｇ／ｄ 、（９００ ±１５０） ｍｇ／ｄ 、（１ ５００ ±１５０） ｍｇ／ｄ ,产后４５ 天采用双能Ｘ线骨密度仪测定全身及各部位骨密度。结果　Ⅰ组多项部位骨密度值明显低于Ⅱ和Ⅲ组;与同年龄组健康妇女腰椎骨密度峰值相比,Ⅰ组仅能维持在（８５ ．１４±６ ．６１） ％ ,并出现个例腰椎骨骨质疏松;Ⅱ组可达（９０ ．７４ ±６ ．５３） ％ ,Ⅲ组则达（１００ ．４４ ±５ ．１９） ％ 。全身多部位骨密度与其均数相关极为显著,其中第３ 腰椎相关性最好;钙摄入量与各部位骨密度均呈正相关。结论　孕期钙摄入量为（３０ ．６８ ±３ ．５６） ｍｍｏｌ／ｄ ,即（１ ２７４ ．６ ±１４７） ｍｇ／ｄ 时,母体经妊娠分娩及短期哺乳仍能维持良好的骨密度,对预防骨质疏松有一定意义。采用骨密度来反映孕产妇钙营养状况时,以腰椎代表性最好。     

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.     

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.     

Calcium intake influences the association of protein intake with rates of bone loss in elderly men and women

BACKGROUND: There is currently no consensus on the effect of dietary protein intake on the skeleton, but there is some indication that low calcium intakes adversely influence the effect of dietary protein on fracture risk. OBJECTIVE: The objective of the present study was to determine whether supplemental calcium citrate malate and vitamin D influence any associations between protein intake and change in bone mineral density (BMD). DESIGN: Associations between protein intake and change in BMD were examined in 342 healthy men and women (aged > or = 65 y) who had completed a 3-y, randomized, placebo-controlled trial of calcium and vitamin D supplementation. Protein intake was assessed at the midpoint of the study with the use of a food-frequency questionnaire and BMD was assessed every 6 mo by dual-energy X-ray absorptiometry. RESULTS: The mean (+/-SD) protein intake of all subjects was 79.1 +/- 25.6 g/d and the mean total calcium intakes of the supplemented and placebo groups were 1346 +/- 358 and 871 +/- 413 mg/d, respectively. Higher protein intake was significantly associated with a favorable 3-y change in total-body BMD in the supplemented group (in a model containing terms for age, sex, weight, total energy intake, and dietary calcium intake) but not in the placebo group. The pattern of change in femoral neck BMD with increasing protein intake in the supplemented group was similar to that for the total body. CONCLUSION: Increasing protein intake may have a favorable effect on change in BMD in elderly subjects supplemented with calcium citrate malate and vitamin D.     

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     

Nutritional status of adventure racers

OBJECTIVE: We describe the usual food intake, body composition, and biochemical profile of adventure racers during their training season and evaluate their energy and nutrient intake in relation to current recommendations for ultraendurance athletes. METHODS: Twenty-four adventure race athletes (18 men and 6 women), 24 to 42 y of age, participated in the study. Food intake was determined with a 3-d food record and body composition by plethysmography. Blood samples were obtained from all subjects for biochemical analyses. All assessments were made during the usual training phase. RESULTS: Female athletes had a higher body fat percentage than did male athletes (20.2 +/- 5.7% versus 12.5 +/- 3.5%). For men and women, food intake was high in protein (1.9 +/- 0.5 g/kg in men, 2.0 +/- 0.4 g/kg in women) and fat (1.6 +/- 0.3 g/kg in men, 1.5 +/- 1.3 g/kg in women). Carbohydrate intake of male athletes was at the lower limit of that recommended (5.9 +/- 1.8 g/kg). For most vitamins and minerals, athletes' intake was adequate, with the exception of magnesium, zinc, and potassium in men and women and vitamin E and calcium in women, which presented a high probability of being inadequate compared with reference values. High blood levels of total cholesterol and low-density lipoprotein cholesterol were found in female athletes (201.0 +/- 44.7 and 104.1 +/- 43.1 mg/dL, respectively) and all other biochemical analyses were within normal reference values. CONCLUSION: The adventure racers presented an inadequate nutritional profile when compared with recommendations for endurance exercise. These athletes need to be educated about consuming an adequate diet to meet the nutritional needs of their activity.     

Food sources of calcium in a sample of African-American an Euro-American collegiate athletes

Adequate calcium intake is integral to bone health as well as for optimal athletic performance. This study was conducted to investigate: (a) food sources of calcium in a sample of collegiate athletes, (b) gender and/or ethnic differences in food sources of calcium, and (c) whether athletes that derive less of their calcium intake from dairy sources increase their calcium intake from supplements or other food sources. Participants were African-American and Euro-American NCAA Division 1-A athletes. Eighty-five men and 59 women participated. Calcium intake for the previous 7-day period was assessed with a brief calcium screen. Men consumed significantly more calcium than women (1,354 vs. 898 mg/day), with female cross-country runners exhibiting the lowest average intake (605 mg/day). Both men and women obtained the majority of their calcium from dairy products and mixed dishes, while men consumed significantly more calcium-fortified foods. Several gender and ethnic interactions for calcium intake from food groups were found. Mean total dairy calcium intake was found to vary according to total calcium intake in men, and supplemental calcium was not used to augment low dairy intakes of calcium in any group. While African-Americans and Euro-Americans athletes were consuming similar levels of calcium, the female athletes in the sample did not get adequate amounts.     

Older black women differ in calcium intake source compared to age- and socioeconomic status-matched white women

Racial disparity in osteoporosis between older black and white women is well established; however, less is known regarding daily dietary and supplemental calcium intake in these populations. Moreover, racial differences in calcium intake are confounded by differences in socioeconomic status (SES). The objective of this study was to assess calcium intake and source in older black women (n=33) and white women (n=33), matched in age and SES. Calcium intake and source were evaluated by interview using a 46-item calcium food frequency questionnaire including all food groups and supplements. Black and white women were identical in SES and matched on age (black women 66.9+/-6.2 years vs white women 67.1+/-5.5 years [mean+/-standard deviation], P=0.85). No significant difference existed for dietary calcium intake between black and white women (974+/-524 vs 1,070+/-600 mg/day; P=0.65) or total calcium intake between black and white women (1,485+/-979 vs 1,791+/-887 mg/day; P=0.15). Dairy foods contributed most to dietary calcium intake in black and white women and differed by race (black women 402+/-269 mg/day, white women, 603+/-376 mg/day; P=0.02). Calcium intake from grains differed by race (black women 205+/-201 mg/day vs white women 130+/-234 mg/day; P=0.010) and fortified cereals were a major source of calcium for black women. Calcium supplementation contributed substantially to total calcium intake in both groups, with more white women (n=23, 70%) using supplements than black women did (n=19, 58%). However, no racial difference existed in supplemented calcium intake (black women, n=19; 889+/-605 vs white women, n=23; 1,034+/-460 mg/day; P=0.20). Our data suggest that total daily dietary and supplemental calcium intakes do not differ, but calcium intake from dairy foods and from grains differ in older black and white women matched in age and SES.     

Dairy intakes affect bone density in the elderly

BACKGROUND: Race and sex differences in the effect of diet on bone mineral density (BMD) at the hip in the elderly are unknown. OBJECTIVES: This study related cross-sectional nutrient and dairy product consumption to hip BMD in white and black men and women aged >60 y and evaluated the influence of nutrient and dairy product consumption on changes in BMD in a white cohort participating in a calcium, vitamin D, or placebo trial. DESIGN: The Health Habits and History Questionnaire was used in 289 white women and 116 white men who participated in the trial and in 265 black women and 75 black men to predict total hip and femoral neck BMD or changes in BMD. RESULTS: Blacks had higher calcium intakes than did whites (700 and 654 mg/d, respectively; P = 0.0094), and men had higher calcium intakes than did women (735 and 655 mg/d, respectively; P = 0.0007). For men, the correlation between total hip BMD and dairy calcium intake after adjustment for age, race, and weight was 0.23 (P < 0.005); this relation was not significant in women (r = 0.02, P = 0.12). Similar results were found for femoral neck BMD. In the longitudinal study, calcium supplementation reduced bone loss from the total hip and femoral neck in those who consumed <1.5 servings of dairy products/d and were <72 y old. CONCLUSIONS: Cross-sectional results indicated that higher dairy product consumption is associated with greater hip BMD in men, but not in women. Calcium supplementation protected both men and women from bone loss in the longitudinal study of whites.     

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。     

Interrelationships of diet, athletic activity, menstrual status, and bone density in collegiate women

We undertook a case-control study to examine the effect of nutritional factors on menstrual function and bone density in collegiate athletes. Three groups, matched with respect to age, height, and weight, were studied: eumenorrheic collegiate athletes, oligomenorrheic collegiate athletes, and eumenorrheic sedentary collegiate control subjects. Menarche was delayed in the eumenorrheic (13.1 y) and oligomenorrheic (14.3 y) athletic groups compared with the sedentary control subjects (12.2 y) (p less than 0.05). Average bone density tended (p = 0.10) to be lower in the oligomenorrheic athletes (158 mg/mL) compared with the eumenorrheic athletes (184 mg/mL) or sedentary control subjects (173 mg/mL). Dietary fiber intake was significantly elevated (p less than 0.05) in the oligomenorrheic athletes (5.74 g/d) compared with the eumenorrheic athletes (3.62 g/d) or sedentary control subjects (2.97 g/d). We conclude that increased dietary fiber intake is associated with menstrual dysfunction of these collegiate athletes. These factors may contribute to decreased bone density.     

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。     

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.