Relation of nutrition, body composition and physical activity to skeletal development: a cross-sectional study in preadolescent females

Nutrition and physical activity level of adolescents with idiopathic scoliosis: a narrative review

Some studies have shown that patients with adolescent idiopathic scoliosis (AIS) have different anthropometric features compared with their peers such as taller stature, lower body mass index, and bone mineral density. Yet the causes explaining these differences remain uncertain. Nutritional intake and status, combined with physical activity, could explain these discrepancies. We aimed to review the current literature on energy and nutrient intake, on nutritional status and physical activity in relation to AIS and to discuss study methodologies and propose avenues for future studies. Studies describing energy or nutrient intake in AIS mostly focused on total energy and calcium and found no difference between AIS and control cohorts. Regarding nutritional status, it was found that AIS patients have lower vitamin D levels than controls and that most patients have insufficient or deficient vitamin D serum levels. Lower concentration of parathyroid hormones and calcitonin were also found in AIS compared to controls as well as anomalies in trace elements. In the studies that have assessed physical activity, three found that AIS girls were less active than controls, but four did not observe differences between groups. In this review, we highlight that nutrition and physical activity are important topics in AIS that require further research as they could help understand anthropometric discrepancies and disease etiology.

Correlation of Bone Mineral Density with Pulmonary Function in Advanced Duchenne Muscular Dystrophy

BACKGROUND

A relationship between bone mineral density (BMD) and physical function has been revealed in the general population and various diseases. However, there is a lack of research investigating the correlation between BMD and respiratory function, one of few measurable physical parameters in patients with advanced Duchenne muscular dystrophy (DMD).

OBJECTIVE

To determine whether pulmonary function parameters, including respiratory muscle strength, are related to BMD.

DESIGN

Retrospective observational study.

SETTING

A tertiary university hospital.

PATIENTS

DMD patients who were over 20 years of age, nonambulatory, and supported by mechanical ventilators.

METHODS

The patients' age, weight, and pulmonary function as well as the BMD of the first and the fourth lumbar vertebra were assessed. Pulmonary function includes forced vital capacity (FVC), unassisted and assisted peak cough flow (UPCF and APCF), maximal expiratory pressure (MEP), and maximal inspiratory pressure (MIP).

MAIN OUTCOME MEASURES

A bivariate correlation for BMD and other pulmonary parameters was calculated, and hierarchical regression analysis was used to determine predictors of spine Z-score.

RESULTS

It was observed that the decrease in the spine BMD was not significantly correlated with age. However, the body mass index (BMI) and all parameters of pulmonary function were correlated with BMD. Partial correlation analysis adjusted by BMI showed that UPCF and APCF were powerful predictors of spine BMD.

CONCLUSIONS

The BMD of the lumbar spine correlated with BMI and PCF in patients with DMD at an advanced stage.

Poor Skeletal Robustness on Lower Extremities and Weak Lean Mass Development on Upper Arm and Calf: Normal Weight Obesity in Middle-School-Aged Children (9 to 12)

Background: Normal weight obesity in children has been associated with excessive body fat, lower bone density and decreased total lean mass. However, no studies have been done into whether normal weight obese children differ in skeletal robustness or lean mass development on the extremities from normal weight non-obese, overweight, and obese peers although these are important indicators of healthy development of children. Methods: Body height, body weight, BMI, four skinfolds, and two limb circumferences were assessed. We calculated total body fat using Slaughter's equations, the Frame index for skeletal robustness and muscle area for the upper arm and calf using Rolland-Cachera equations. Using national references of BMI and measured skinfolds, three subgroups of participants (9-12 years) consisting of 210 middle-school-aged children (M-age = 11.01 ± 1.05)-110 girls and 100 boys-were selected: (A) overweight obese (OWOB) (n = 72); (B) normal weight obese (NWO) (n = 69); and, (C) normal weight non-obese (NWNO) (n = 69). All values, were converted to Z-scores to take account of participant's sex and age. Results: NWO children had significantly poorer skeletal robustness on lower extremities and poorer muscle area on the upper arm and calf compared to NWNO counterparts with significantly higher evidence in boys-skeletal robustness NWO boys: Z-score = -0.85; NWO girls: Z-score = -0.43; lean mass on the calf: NWO boys Z-score = -1.34; NWO girls: Z-score = -0.85. The highest skeletal robustness-but not muscle area on the calf-was detected in OWOB children. Conclusions: Further research should focus on whether this poor skeletal and lean mass development: (1) is a consequence of insufficient physical activity regimes; (2) affects physical fitness of NWO children and could contribute to a higher prevalence of health problems in them. We have highlighted the importance of the development of a simple identification of NWO children to be used by pediatricians.

Assessing the efficacy and external validity of interventions promoting calcium or dairy intake in young adults: A systematic review with meta-analysis

Calcium and dairy products have a role in the prevention of chronic diseases and attainment of peak bone mass, during adolescence to young adulthood. However, intakes are often suboptimal and interventions to improve consumption of food sources are needed. This systematic review aimed to investigate the efficacy and external validity of interventions promoting calcium or dairy foods among young adults. Eight databases were searched from inception to identify relevant studies. Inclusion criteria included those aged 18 to 35 years in an intervention promoting calcium or dairy food intake. The mean age of the participants was 19.9 ± 1.4 years. Of the 16 studies that met the selection criteria, five studies were included in the meta-analyses for calcium (pooled effect size 0.35, 95% CI 0.04 to 0.67) and three studies for dairy (pooled effect size 0.31, 95% CI 0.11 to 0.50). The quality of the body of evidence was determined using the GRADE system, and was of overall low quality with high risk of bias. Our review suggests young adults respond favorably to interventions but the effect size is small.

A Cross-Sectional Study of the Association of VDR Gene, Calcium Intake, and Heel Ultrasound Measures in Early Adulthood

The acquisition of a high adult peak bone mass (PBM) is considered an important determinant of osteoporotic risk later in life. Genetic and environmental factors determine optimal PBM acquisition in early adulthood. The aim of this study was to test the association of vitamin D receptor (VDR) gene polymorphisms and dietary calcium intake with the bone mass of young adults. The study population comprised a total of 305 individuals (mean age 20.41; SD 2.36) whose bone mass was assessed through heel ultrasound [quantitative ultrasound measurements (QUS)] measurements (BUA, dB/MHz). The FokI G/A, rs9729 G/T, and TaqI G/A polymorphisms were selected as genetic markers of VDR. A significant difference in BUA values was observed according to gender (females 82.96; SD 15.89 vs. males 97.72; SD 16.50; p < 0.00001). The mean dietary calcium intake of the study group (827.84 mg/day; SD 347.04) was lower than the dietary reference intake for young adults (1000 mg/day) and had no association with BUA. None of the three VDR polymorphisms tested showed an association with BUA. Similarly, the analysis of VDR 3' haplotypes, estimated using rs9729 and Taq1 as tag SNPs, did not reveal any significant association with QUS traits. Our results confirm the existence of different heel QUS for women and men, as well as a tendency towards low calcium consumption by young adults, and they also suggest that the VDR gene does not play a major role in the genetic determination of QUS parameter in early adulthood.

Reference data and percentile curves of body composition measured with dual energy X-ray absorptiometry in healthy Chinese children and adolescents

Measurements of body composition by dual-energy X-ray absorptiometry (DXA) have evident value in evaluating skeletal and muscular status in growing children and adolescents. This study aimed to generate age-related trends for body composition in Chinese children and adolescents, and to establish gender-specific reference percentile curves for the assessment of muscle-bone status. A total of 1541 Chinese children and adolescents aged from 5 to 19 years were recruited from southern China. Bone mineral content (BMC), lean mass (LM) and fat mass (FM) were measured for total body and total body less head (TBLH). After 14 years, total body LM was significantly higher in boys than girls (p < 0.001). However, total body FM was significantly higher in girls than boys in age groups 13-19 years (p < 0.01). Both LM and FM were consistent independent predictors of total body and subcranial bone mass in both sexes, even after adjustment for the well-known predictors of BMC. The results of multiple linear regression identified LM as the stronger predictor of total body and subcranial skeleton BMC while the fat mass contributed less. For all the subjects, significant positive correlations were observed between total body LM, height, total body BMC and subcranial BMC (p < 0.01). Subcranial BMC had a better correlation with LM than total body BMC. We have also presented gender-specific percentile curves for LM-for-height and BMC-for-LM which could be used to evaluate and follow various pediatric disorders with skeletal manifestations in this population.

Combined effects of interaction between physical activity and nutrition on bone health in children and adolescents: a systematic review

CONTEXT

Osteoporosis is a major public health concern worldwide. Understanding the roles of diet and physical activity in ensuring adequate bone mass accrual during childhood and adolescence may help identify strategies to reduce the risk of osteoporotic fractures later in life.

OBJECTIVE

The present systematic review was conducted to provide an overview of the current knowledge of the combined effects of physical activity and diet on bone mass accrual in children and adolescents.

DATA SOURCES

Data were obtained via searches of the PubMed, EMBASE, SPORTDiscus, and ISI Web of Science databases.

STUDY SELECTION

Studies published in English and Spanish between 1887 and August 2013 were eligible for inclusion. Two investigators evaluated the studies against the inclusion and exclusion criteria. A total of 14 studies (7 cross-sectional and 7 experimental) were included in the review.

DATA EXTRACTION

The Pedro score and the Black and Down's checklist were used to evaluate the methodological quality of the experimental and the cross-sectional studies, respectively. Study characteristics were summarized in accordance with the review's PICO criteria.

DATA SYNTHESIS

Significant exercise-by-calcium interaction was detected at several different bone sites.

CONCLUSIONS

Although the results of cross-sectional studies were inconsistent, the results of randomized controlled trials showed that exercise has the potential to improve bone health under conditions of adequate calcium intake.

Association between lean and fat mass and indicators of bone health in prepubertal caucasian children

BACKGROUND/AIMS

Childhood and adolescence are critical periods for bone growth. The independent association between lean and fat mass and indicators of bone health in children is not yet known. We aim to examine the association between each of lean and fat mass and indicators of bone health in 8- to 10-year-old prepubertal Caucasian children.

METHODS

We present a cross-sectional analysis of baseline data from the QUebec Adipose and Lifestyle InvesTigation in Youth (QUALITY) cohort which study the natural history of obesity. Study participants (n = 483) included prepubertal children aged 8-10 years and their biological parents. Whole-body bone mineral content (BMC, g), bone area (cm²), bone mineral density (BMD, g/cm²), lean mass (kg), and fat mass (kg) were measured by dual-energy X-ray absorptiometry. Data analyses include multiple linear regressions adjusted for potential confounding variables.

RESULTS

A 1-kg increase in lean mass was associated with 28.42 g, 19.88 cm², and 0.007 g/cm² increase in whole-body BMC, bone area and BMD respectively. A 1-kg increase in fat mass was associated with 9.32 g, 8.02 cm², and 0.002 g/cm² increase in whole-body BMC, bone area and BMD, respectively.

CONCLUSION

Increasing lean mass in children may help optimize bone acquisition and prevent future osteoporosis.

Normative data for quantitative calcaneal ultrasonometry in Turkish children aged 6 to 14 years: relationship of the stiffness index with age, pubertal stage, physical characteristics, and lifestyle

OBJECTIVES

Quantitative ultrasonometry is commonly used to assess bone health. The aim of this study was to define normative data for the stiffness index of the calcaneus in healthy Turkish children.

METHODS

Quantitative ultrasonometric measurements of the calcaneus were obtained in 1617 healthy schoolchildren (811 boys and 806 girls) aged 6 to 14 years.

RESULTS

The stiffness index increased by 19.3% and 12% in boys and girls, respectively. The greatest increases were seen in the age groups of 12 to 13 and 13 to 14 years in boys (3.9%) and 11 to 12 and 12 to 13 years in girls (4.1%). There was a significant increase in stiffness index values among all Tanner stages except stage 4 (P < .05). Although the stiffness index was related to age, weight, and height, no correlation was seen between the stiffness index and calcium intake or physical activity.

CONCLUSIONS

This study provides stiffness index data by age group and Tanner stage that may be useful for assessment of the bone status of Turkish children and can serve as comparative data for other patient groups.

Message framing, it does a body good: Effects of message framing and motivational orientation on young women’s calcium consumption

We investigated the effects of gain-framed versus loss-framed messages and motivational orientation on calcium consumption. After completing a motivational orientation scale (behavioral inhibition system/behavioral activation system), undergraduate women ( N = 141) were randomly assigned to read a gain-framed or loss-framed pamphlet promoting calcium consumption. Calcium consumption was assessed 1 month later. For calcium supplement behavior, a gain-framed advantage was observed for behavioral activation system–oriented individuals, whereas a loss-framed advantage was observed for behavioral inhibition system–oriented individuals. For dietary calcium intake, a gain-framed advantage was observed among behavioral activation system–oriented individuals; however, no framing effect emerged for behavioral inhibition system–oriented individuals. The success of framed messages depends on the message recipient’s motivational orientation.

Parental smoking during pregnancy and offspring bone mass at age 10 years: findings from a prospective birth cohort

We investigated an intrauterine influence of maternal smoking during pregnancy on childhood bone mass. Daughters, but not sons, of mothers who smoked had higher bone mass at age 10years. This appears to be due to familial factors related to parental smoking influencing increased offspring adiposity rather than a direct intrauterine effect.

INTRODUCTION

Neonatal studies have demonstrated an adverse relationship between maternal smoking in pregnancy and foetal bone mineral accrual. We aimed to investigate an intrauterine influence of maternal smoking during pregnancy on offspring bone mass at mean age 9.9 years.

METHODS

We compared associations of maternal and paternal smoking in pregnancy with offspring total body less head (TBLH) and spine bone mineral content (BMC), bone area (BA), bone mineral density (BMD) and area-adjusted BMC (ABMC) in 7,121 children in the Avon Longitudinal Study of Parents and Children.

RESULTS

Maternal smoking in any trimester was associated with increased TBLH BMC, BA and BMD in girls (mean difference [95% CI] (sex-specific SD scores), 0.13 [0.05-0.22], 0.13 [0.04-0.21], 0.13 [0.04-0.22], respectively) but not boys (0.01 [-0.07-0.09], 0.00 [-0.08-0.08], 0.04 [-0.05-0.12]), and also with spine BMC, BA and BMD in girls (0.13 [0.03-0.23], 0.12 [0.03-0.22], 0.10 [0.00-0.21]) but not boys (0.03 [-0.06-0.12], 0.00 [-0.09-0.09], 0.05 [-0.04-0.14]), but not with ABMC. Paternal smoking associations were similar, with no statistical evidence for a difference between maternal and paternal effects. Maternal associations increased on adjustment for offspring birth weight and gestational age, but attenuated to the null after adjustment for current height and weight.

CONCLUSIONS

We found little evidence that maternal smoking was related to bone mass in boys. In girls, maternal smoking associations were similar to those of paternal smoking, suggesting that these were attributable to shared familial characteristics, not intrauterine mechanisms.

Are new generations of female college-student populations meeting calcium requirements: comparison of American and Croatian female students

We compared calcium (Ca) sources and intake, as well as multivitamin/mineral supplement use between female students with nutrition/health background and those from general-student-populations. 314 participants 18–37 y, including 57 African-Americans and 54 Caucasian-Americans recruited from Nutrition and/or other Health Sciences departments (NHS), and 100 African-American and 103 Croatian women representing general-student-population (GSP), completed food frequency questionnaire assessing their usual Ca intake and supplement use. NHS populations met recommendations and consumed significantly more Ca, particularly from dairy sources, and were more likely to take supplements than GSP groups, suggesting that health education may influence Ca intake.

Bone and lean mass inter-arm asymmetries in young male tennis players depend on training frequency

Professional tennis players (TP) have marked inter-arm asymmetry in bone mass (BMC) and density (BMD). To determine if this asymmetry is influenced by training frequency and volume, we studied 24 young tennis players (mean age 10.6 years, Tanner 1-2), 17 physically active control boys (CG) and ten male professional tennis players. Young TP were divided into two groups depending on the number of training days per week (TP5: 5 days/week, n = 10; TP2: 2 days/week, n = 14). In young TP, the dominant arm (DA) compared to the non-dominant arm (NDA) had greater lean mass (TP5, 13.3 +/- 2.0% and TP2, 8.3 +/- 1.3%), BMC (TP5, 22.4 +/- 4.1% and TP2, 12.1 +/- 2.2%), bone area (TP5, 15.6 +/- 3.3% and TP2, 7.9 +/- 2.2%) and BMD (TP5, 4.6 +/- 1.5% and TP2, 3.8 +/- 0.6%). Inter-arm asymmetry in lean mass, BMC and bone area was greater in TP5 than TP2, being related to the number of weekly hours devoted to tennis (r = 0.45-52, P < 0.05). No significant differences in lumbar spine or femoral neck BMC or BMD were observed between TP5, TP2 and CG. In professional TP, the DA had 18, 32, 11 and 15% greater lean mass, BMC, bone area and BMD than the NDA. Thus, TP5 had 69% of the inter-arm asymmetry in BMC observed in professional TP and a similar inter-arm asymmetry in bone area, although this comparison may not be generalisable. Young tennis players have increased BMC, bone area and lean mass in dominant arm, which magnitude depends on the number of weekly hours devoted to tennis.

Low bone mineral density in children and adolescents with inflammatory bowel disease: a population-based study from Western Sweden

BACKGROUND

Low bone mineral density (BMD) has been recognized as a potential problem in children with inflammatory bowel disease (IBD). The aim of the study was to investigate BMD in Swedish children and adolescents with IBD and to evaluate possible factors affecting BMD.

METHODS

To evaluate BMD, all patients (n = 144) underwent a dual-energy X-ray absorptiometry (DXA) of the whole body and the spine. BMD values were expressed as Z-scores using normative pediatric data from Lunar (GE Medical Systems).

RESULTS

In this population-based study, the lowest BMD values were found in the lumbar spine. The entire IBD group showed significantly lower BMD Z-scores of the lumbar spine (L2-L4) in comparison to healthy references (-0.8 standard deviation [SD], range -5.9 to 3.7 SD, P < 0.001). Decreased BMD with a Z-score < -1 SD occurred in 46.7% of the individuals with Crohn's disease (CD) and in 47.0% of those with ulcerative colitis (UC). Low BMD with a Z-score ≤ -2 SD was present in 26.7% of the patients with CD and in 24.1% of the UC patients. In a multiple regression model with BMD lumbar spine as the depending variable, possible factors associated with lower BMD were male gender, low body mass index (BMI), and treatment with azathioprine.

CONCLUSIONS

Low BMD is prevalent in Swedish pediatric patients with IBD. Possible risk factors for lower BMD are male gender, low BMI, and treatment with azathioprine, as a probable marker of disease course severity.

Diet quality in Croatian university students: Energy, macronutrient and micronutrient intakes according to gender

The aim of the study was to evaluate diet quality and nutrient intakes in Croatian university students, which are missing for the past 15 years, and also to report the prevalence of overweight/obesity and underweight. The subjects were 663 students (average age 22 years), representing 0.6% of all Croatian university students. The Quantified Food Frequency Questionnaire, checked for reproducibility and validity, was used for dietary assessment. Students on average had an adequate number of daily meals and snacks, but consumption of breakfast was irregular, particularly for men. The average energy intake was 130.1% of the dietary reference intake and the protein intake was more than double the dietary reference intake in 64.3% students. Dietary fiber, iron (in females), calcium, zinc, folate, and vitamins C, A and E intake were below recommendations in both genders. Only 3.8% of females and 21.9% of males were overweight/obese (body mass index >25 kg/m(2)). Nutrient intakes significantly differed according to gender and better macronutrient but not micronutrient intakes were observed in females.

Sugar-added beverages consumption among kindergarten children of Crete: effects on nutritional status and risk of obesity

Objective

To assess the intake of sugar-added beverages such as soft drinks and commercially available fruit juices in kindergarten children, and to examine its association with obesity indices, physical activity levels and dietary habits.

Methods

A total of 856 children aged 4–7 years living in Crete, Greece in 2004–5 were included in this cross-sectional study. Nutrient and food intake was assessed with the use of 3-day weighed food records. Body measurements were used in order to assess BMI and waist circumference, and moderate-to-vigorous physical activity was calculated with the use of a questionnaire.

Results

Approximately 59.8% of all children consumed sugar-added beverages on a daily basis. High intake of sugar-added beverages (> 250 g/day) was associated with low intakes of calcium (p < 0.001), vitamin A and E (p < 0.010), fruits and vegetables (p = 0.007), and milk and yogurt (p = 0.048). Compared to non or low consumers, high consumers of sugar-added beverages (> 250 g/day) had higher BMI levels and two times greater risk of being overweight and/or obese (OR:2.35, p = 0.023).

Conclusion

High intake of sugar-added beverages in kindergarten children is associated with poor eating habits and inadequate nutrient intake, as well as increased risk for developing childhood obesity.

Peak bone density in Croatian women: variations at different skeletal sites

It is known that different skeletal sites have different peak bone mass at different times and lose bone at different rates. The purpose of the study was to assess bone mineral density (BMD) in healthy female student population (N=220), aged 18-25 yr and to analyze whether young women of that age have already started to lose the bone mass at the trabecular and cortical parts of skeleton. The influence of dietary intake and physical activity on their bone mass was also assessed. BMD was measured, using dual-energy X-ray absorptiometry technique, in spine, proximal femur, and distal third of the radius and in total body. Significant negative correlation between age and bone mass was found in all skeletal regions (p<0.05 spine; p<0.0001 total femur; and p<0.01 total body) except in cortical part of the radius. Peak bone mass in young Croatian women was achieved before the age of 20, but later in the long-bone cortical skeleton, where BMD continued to increase after mid-20s. The BMD values are comparable with those from National Health and Nutrition Examination Survey study, except for the cortical part of the radius, where it is significantly lower. Body weight and physical activity were the most significant positive predictors of bone density in all measured sites.

Independent and combined effect of nutrition and exercise on bone mass development

Food intake provides the necessary components for adequate metabolic functions in bone. Calcium, phosphorus, vitamin D, magnesium, proteins, and fluoride are some of the most important nutrients in this regard. These have different effects on bone mass. Additionally, exercise has been shown to elicit osteogenic responses in bone development; indeed, it seems to potentiate, for example, the effect of calcium supplementation on bone mass. However, the nutrition-exercise-bone mass relationship is complex and needs further in-depth investigation. As a first step, therefore, we reviewed current knowledge about the role of nutrition on the development of bone tissue and how physical activity affects the nutrient-bone relationship.

The effect of calcium intake and physical activity on bone quantitative ultrasound measurements in children: a pilot study

Environmental factors, such as nutritional status, physical activity, and drug therapy, can affect bone mineralization. Our objective was to evaluate the relationship between nutritional status, physical activity, and bone mineralization as assessed by multisite quantitative ultrasound technology in children. The study group comprised 67 children, aged 6-17 years (mean, 9.4), attending a primary care clinic. Data on calcium intake and physical activity were collected using a detailed questionnaire. Speed of sound measurements were performed at the distal 1/3 radius and the midshaft tibia using Sunlight Omnisense apparatus. The reported mean calcium intake was 1105 mg/day. There was a significant difference in Z-scores at the radius and tibia between the low-and high-calcium-intake groups (P = 0.004, P = 0.035, respectively). A similar difference was found between the low-and normal-physical-activity groups (P = 0.015, P = 0.036, respectively). In this pilot study, a positive association was found between calcium intake, physical activity, and bone status, as assessed by the quantitative ultrasound technique.

Correlation of obesity and osteoporosis: effect of fat mass on the determination of osteoporosis

It was previously believed that obesity and osteoporosis were two unrelated diseases, but recent studies have shown that both diseases share several common genetic and environmental factors. Body fat mass, a component of body weight, is one of the most important indices of obesity, and a substantial body of evidence indicates that fat mass may have beneficial effects on bone. Contrasting studies, however, suggest that excessive fat mass may not protect against osteoporosis or osteoporotic fracture. Differences in experimental design, sample structure, and even the selection of covariates may account for some of these inconsistent or contradictory results. Despite the lack of a clear consensus regarding the impact of effects of fat on bone, a number of mechanistic explanations have been proposed to support the observed epidemiologic and physiologic associations between fat and bone. The common precursor stem cell that leads to the differentiation of both adipocytes and osteoblasts, as well the secretion of adipocyte-derived hormones that affect bone development, may partially explain these associations. Based on our current state of knowledge, it is unclear whether fat has beneficial effects on bone. We anticipate that this will be an active and fruitful focus of research in the coming years.

Influence of body composition, muscle strength, diet and physical activity on total body and forearm bone mass in Chinese adolescent girls

The aim of the present study was to determine association between body composition, muscle strength, diet and physical exercise with bone mineral content (BMC) and bone area (BA) in 283 Chinese adolescent girls aged 15 years in Beijing, China. Body composition, pubertal stage, physical activity and dietary intakes were assessed using standard validated protocols. Total body and forearm bone, lean body mass (LBM) and fat body mass (FBM) were determined by dual X-ray absorptiometry. Multivariate linear regression analyses were carried out to examine the predictors of BMC and BA, after controlling for potential confounders. The subjects had a mean age of 15·0 (sd 0·9) years and 99·6 % of them had reached menarche. Multivariate analyses showed that LBM, FBM, handgrip muscle strength and milk intake were significant independent determinants of BMC and BA of the total body and/or forearm sites. LBM was found to be a stronger independent determinant than FBM of BMC and BA, whereas handgrip muscle strength was only found as significant determinant of BMC and BA at the forearm sites than in total body BMC and BA. Further, total physical activity level had a significant positive association with handgrip and LBM. This suggested that greater muscle strength and higher LBM may reflect higher levels of physical activity. Therefore, continuous healthy lifestyle practices such as adequate intake of milk and continuous participation in physical activity should be encouraged throughout adolescence to optimise bone growth during this period.

Vitamin D status of apparently healthy schoolgirls from two different socioeconomic strata in Delhi: relation to nutrition and lifestyle

Forty to fifty per cent of skeletal mass, accumulated during childhood and adolescence, is influenced by sunlight exposure, physical activity, lifestyle, endocrine status, nutrition and gender. In view of scarce data on association of nutrition and lifestyle with hypovitaminosis D in Indian children and adolescents, an in-depth study on 3,127 apparently healthy Delhi schoolgirls (6-18 years) from the lower (LSES, n 1,477) and upper socioeconomic strata (USES, n 1650) was carried out. These girls were subjected to anthropometry and clinical examination for hypovitaminosis D. Girls randomly selected from the two strata (LSES, n 193; USES, n 211) underwent detailed lifestyle, dietary, biochemical and hormonal assessment. Clinical vitamin D deficiency was noted in 11.5 % girls (12.4 % LSES, 10.7 % USES). USES girls had significantly higher BMI than LSES counterparts. Prevalence of biochemical hypovitaminosis D (serum 25-hydroxyvitamin D < 50 nmol/l) was seen in 90.8 % of girls (89.6 % LSES, 91.9 % USES, NS). Mean intake of energy, protein, fat, Ca, vitamin D and milk/milk products was significantly higher in USES than LSES girls. Conversely, carbohydrate, fibre, phytate and cereal intakes were higher in LSES than USES girls. Physical activity and time spent outdoors was significantly higher in LSES girls (92.8 v. 64 %, P = 0.000). Significant correlation between serum 25-hydroxyvitamin D and estimated sun exposure (r 0.185, P = 0.001) and percentage body surface area exposed (r 0.146, P = 0.004) suggests that these lifestyle-related factors may contribute significantly to the vitamin D status of the apparently healthy schoolgirls. Hence, in the absence of vitamin D fortification of foods, diet alone appears to have an insignificant role.

A 2-year prospective study of bone metabolism and bone mineral density in adolescents with anorexia nervosa

Osteopenia and osteoporosis are complications of adolescent anorexia nervosa (AN) and may result in a permanent deficit of bone mass in adulthood. It is still unclear if a complete catch-up in bone mineral density (BMD) is possible after weight rehabilitation in AN. METHODS. We investigated bone formation (bAP, PICP), bone resorption (CTX) and BMD (lumbar spine, femoral neck) along with endocrinological parameters in 19 girls with AN (14.4 +/- 1.6 years) and in 19 healthy controls for 2 years after inpatient re-feeding. RESULTS. Re-feeding normalised bone formation activity in patients. The pattern of bone turnover in patients after 2 years was similar to the pattern healthy controls had shown 2 years before. BMD of patients was significantly lower than in controls and did not change throughout the entire study. CONCLUSIONS. Weight rehabilitation leads to prolonged normalization of bone turnover in adolescent AN. Since we could not observe a "catch up" effect in BMD of girls with AN in a 2-year follow-up, BMD of these patients needs to be carefully monitored until adulthood to detect early osteoporosis.

Bone mineral status after treatment of malignant lymphoma in childhood and adolescence

The relationship between bone mineral mass and cumulative dose of corticosteroids (CDC) was investigated in 42 children and adolescents treated for Hodgkin disease (HD; n = 22) and non-Hodgkin lymphoma (NHL; n = 20). The median age at the time of the study was 24.1 years for HD survivors and 14.1 years for NHL survivors. Dual-energy X-ray absorptiometry [bone mineral density of the lumbar spine (LS-BMD) expressed as Z-scores] and peripheral quantitative computed tomography at the distal radius [trabecular volumetric BMD (vBMD-trab)] were undertaken. Osteopenia (Z-score < -1.00) was found in 9/22 patients with HD and 10/20 with NHL, while 34% (HD = 6, NHL = 8) had a vBMD-trab below the normal range. The CDC correlated inversely with LS-BMD Z-score (r =-0.41, P = 0.007). There was a statistically significantly higher vBMD-trab in patients who received low (1-4 g/m(2)) compared with high (>or=20 g/m(2)) CDC (P = 0.031). Treatment of malignant lymphoma with high CDC is a risk factor for development of osteopenia.

Influence of sports participation and menarche on bone mineral density of female high school athletes

Weight-bearing exercise during adolescence may enhance peak bone mineral density (BMD) and reduce osteoporosis risk. The association of sports participation before and after menarche with areal BMD (by central DXA) was investigated in 99 female high school athletes (age 15.5+/-1.3 year). The frequency and duration of structured sports (school-based or other organized team) were assessed using an interviewer-assisted questionnaire. Overall, the average number of years of weight-bearing sport participation was 7.4+/-3.4 years; 72% of the athletes began sport participation before menarche. Training patterns and BMD were examined by tertiles of yearly weight-bearing sport participation (hours/year) before (WBpre), after (WBpost) menarche, and in total (WBtotal). After adjusting for chronological age, gynecological age, and BMI, compared to athletes in the WBtotal low tertile, athletes in the WBtotal high tertile had significantly greater BMD at the spine (p=0.009), total hip (p=0.03), trochanter (p=0.03), and total body (p=0.009). Similar patterns were found by WBpre or WBpost status, separately, with the exception of spine BMD which was significantly different across tertiles in WBpost only (p<0.01). While the number of years of participation was similar across tertiles of WBtotal, the number of months/year was significantly greater among athletes in the high tertile than athletes in the low tertile (9.2+/-3.4 month/year versus 5.0+/-2.9 month/year, respectively (p<0.001)). These results indicate that near year-round participation in structured weight-bearing sports during early adolescence may help young girls optimize bone mineral accrual during these critical years, and may decrease their risk of osteoporosis with advancing age.

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 7d 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 (417mg/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 (partialR21·7%). The results indicate that premenarcheal girls should be encouraged to optimise nutrition and Ca intake and exercise regularly to achieve maximum peak bone mass.

Effect of nutrition and physical activity on bone health of children and young adults

The development and maturation of the skeletal system starts in utero. The bone-growth process starts with the addition of cells; these cells grow and incorporate materials that increase bone strength. During puberty, this process is accelerated to the degree that approximately 25% of the total bone mass is accumulated. Failure to meet the increased demand for bone-building materials during an accelerated growth period may increase fracture tendency. The greater is the bone mass at the start of puberty; the better is the final outcome at full maturity. This is in accordance with the tracking theory (keeping bone growth along a steady percentile). Nutrition and physical activity will facilitate bone accumulation from an early age. Therefore, a program for bone health that includes physical activity and nutrition should be introduced early in the prepubertal age. There are differences in the timing and rate of bone-mass accumulation of different parts of the skeleton so that measurement of one bone may not represent the whole skeleton. In addition, bone measurements using different devices cannot be compared. Therefore, until a universal standard is reached, repeated measurements of one individual should be done using the same apparatus. The choice of the apparatus should be made so that the relevant part of the skeleton is measured. Repeated measurements of bone may detect bone mass loss much earlier than the osteoporosis line is reached. This suggests that a dynamic measure of bone growth rate similar to height velocity should be adopted, since both parameters in an optimal setting follow a steady percentile and falling of the percentile in both parameters needs an etiological diagnosis.

The role of leptin in anorexia nervosa: clinical implications

Leptin is a hormone with pleiotropic functions affecting several tissues. Because leptin has a crucial role in the adaptation of an organism to semi-starvation, anorexia nervosa (AN) serves as a model disorder to elucidate the functional implications of hypoleptinaemia; vice versa, several symptoms in patients with this eating disorder are related to the low leptin levels, which are characteristic of acute AN. Weight gain in AN patients can induce relative hyperleptinaemia in comparison to controls matched for body mass index; circulating leptin concentrations in AN patients thus transverse from subnormal to supranormal levels within a few weeks. We review findings on leptin secretion in AN and focus on implications, particularly for the hypothalamus-pituitary-gonadal axis, bone mineral density and physical hyperactivity. Undoubtedly, the elucidation of leptin's function as a trigger of diverse neuroendocrine adaptations to a restricted energy intake has substantially advanced our knowledge of the pathogenesis of distinct symptoms of AN, including amenorrhoea that represents one of the four diagnostic criteria. The fact that hypoleptinaemia can induce hyperactivity in a rat model for AN has led to a series of studies in AN patients, which support the notion that application of leptin to severely hyperactive patients might prove beneficial.

Girls' calcium intake is associated with bone mineral content during middle childhood

We examined longitudinally the association between calcium intake and total body bone mineral content (TBBMC) in 151 non-Hispanic white girls. Intakes of dairy, energy, and calcium were assessed using three 24-h dietary recalls in girls at ages 5, 7, 9, and 11 y. We assessed their total-body bone mineral content with dual-energy X-ray absorptiometry at ages 9 and 11 y. Dairy foods comprised the major contributor (70%) to calcium intake over the 6-y period; 28% of calcium came from other foods, and 2% from supplements. By age 9 and 11 y, the majority of girls did not meet calcium recommendations. Higher calcium intake at ages 7 and 9 y was associated with higher TBBMC at age 11 y. Calcium intake at age 9 y was also positively associated with TBBMC gained from age 9 to 11 y. Calcium intake at age 11 y was not correlated with TBBMC at the same age. Relations between calcium intake and TBBMC did not differ for total calcium and for calcium from dairy sources, likely reflecting the fact that dairy products were the major source of calcium in this sample. Results from the present study provide new longitudinal evidence that calcium intake, especially calcium from dairy foods, can have a favorable effect on girls' TBBMC during middle childhood.

The impact of childhood obesity on musculoskeletal form

Despite the greater prevalence of musculoskeletal disorders in obese adults, the consequences of childhood obesity on the development and function of the musculoskeletal system have received comparatively little attention within the literature. Of the limited number of studies performed to date, the majority have focused on the impact of childhood obesity on skeletal structure and alignment, and to a lesser extent its influence on clinical tests of motor performance including muscular strength, balance and locomotion. Although collectively these studies imply that the functional and structural limitations imposed by obesity may result in aberrant lower limb mechanics and the potential for musculoskeletal injury, empirical verification is currently lacking. The delineation of the effects of childhood obesity on musculoskeletal structure in terms of mass, adiposity, anthropometry, metabolic effects and physical inactivity, or their combination, has not been established. More specifically, there is a lack of research regarding the effect of childhood obesity on the properties of connective tissue structures, such as tendons and ligaments. Given the global increase in childhood obesity, there is a need to ascertain the consequences of persistent obesity on musculoskeletal structure and function. A better understanding of the implications of childhood obesity on the development and function of the musculoskeletal system would assist in the provision of more meaningful support in the prevention, treatment and management of the musculoskeletal consequences of the condition.

PIXImus bone densitometer and associated technical measurement issues of skeletal growth in the young rat

The PIXImus dual-energy X-ray absorptiometer (DXA) is designed to measure body composition, bone mineral content (BMC), area (BA), and density (BMD) in mice and rats. The aims of this study were to longitudinally measure BMC, BA, and BMD in growing rats and to identify potential technical problems associated with the PIXImus. Total femur and lumbar DXA measurements, body weight, and length of initially 3-week-old rats (n = 10) were taken at weeks 5, 9, and 14. BMC and BMD of femoral metaphyseal and diaphyseal regions rich in trabecular and cortical bone, respectively, were obtained. Results showed significant increases in body weight, total femur BMC and BMD, lumbar area, length, BMC, and BMD at each time point. There was a significant positive correlation between body weight and total femur BMD (r = 0.97, P < 0.001) as well as lumbar BMD (r = 0.99, P < 0.001). BMD values for the femoral metaphyseal region and the lumbar spine were also positively correlated (r = 0.96, P < 0.01). Several technical issues (e.g., positioning of animals), difficulties (e.g., in analysis of images), and limitations (e.g., inability to detect underdeveloped calcified bone in growing animals and bone edge detection) of the software pertinent to the PIXImus were evident. In conclusion, despite limitations in the software, the PIXImus is a valuable tool for studying skeletal development of growing rats.

How does Exercise Affect Bone Development during Growth?

It is increasingly accepted that osteoporosis is a paediatric issue. The prepubertal human skeleton is quite sensitive to the mechanical stimulation elicited by physical activity. To achieve the benefits for bone deriving from physical activity, it is not necessary to perform high volumes of exercise, since a notable osteogenic effect may be achieved with just 3 hours of participation in sports. Physical activity or participation in sport should start at prepubertal ages and should be maintained through the pubertal development to obtain the maximal peak bone mass potentially achievable. Starting physical activity prior to the pubertal growth spurt stimulates both bone and skeletal muscle hypertrophy to a greater degree than observed with normal growth in non-physically active children. High strain-eliciting sport like gymnastics, or participation in sports or weight-bearing physical activities like football or handball, are strongly recommended to increase the peak bone mass. Moreover, the increase in lean mass is the most important predictor for bone mineral mass accrual during prepubertal growth throughout the population. Since skeletal muscle is the primary component of lean mass, participation in sport could have not only a direct osteogenic effect, but also an indirect effect by increasing muscle mass and hence the tensions generated on bones during prepubertal years.

Calcium and Exercise Affect the Growing Skeleton

Adequate dietary calcium and bone-stimulating exercise during growth are known to affect skeletal development, but the combined effects of dietary calcium and osteogenic exercise have received scant attention. Animal research has showed a compensatory effect of impact loading on calcium-deprived bones, while various human studies have suggested compensatory, additive, or possibly synergistic effects in certain skeletal locations. Current evidence suggests that the best strategy for strong bones by the end of childhood may be either high-impact exercise with a moderate or greater calcium intake or a combination of moderate-impact exercise and adequate calcium during growth.

The relationship of dietary and lifestyle factors to bone mineral indexes in children

OBJECTIVE

To identify factors related to children's bone mineral indexes at age 8 years, and to assess bone mineral indexes in the same children at ages 6 and 8 years.

DESIGN

Bone mineral content (BMC [g]) and bone mineral density (BMD; calculated as g/cm 2 ) were measured by dual-energy x-ray absorptiometry (DEXA) in children and their mothers when the children were 8 years of age. A subset of children had an earlier DEXA assessment at age 6 years. Children's dietary intake, height, weight, and level of sedentary activity were assessed as part of a longitudinal study from ages 2 months to 8 years.

SUBJECTS/SETTING

Fifty-two healthy white children (25 male, 27 female) and their mothers. Main outcome measures Children's total BMC and BMD at age 8 years.

STATISTICAL ANALYSES PERFORMED

Correlations and stepwise multiple regression analyses.

RESULTS

Factors positively related to children's BMC at age 8 years included longitudinal intakes (ages 2 to 8 years) of protein, phosphorus, vitamin K, magnesium, zinc, energy, and iron; height; weight; and age ( P < or = .05). Factors positively related to children's BMD at age 8 years included longitudinal intakes of protein and magnesium ( P < or = .05). Female sex was negatively associated with BMC and BMD at age 8 years ( P < or = .05). Children's bone mineral indexes at ages 6 and 8 years were strongly correlated ( r =0.86, P < .0001 for BMC; r =0.92, P <.0001 for BMD).

CONCLUSIONS

Because many nutrients are related to bone health, children should consume a varied and nutrient-dense diet.

Impact of anthropometric, lifestyle, and body composition variables on ultrasound measurements in school children

Quantitative ultrasound (QUS) measurement at hand phalanges was demonstrated to be a reliable method to assess skeletal maturation during childhood and adolescence. The aim of the study was to evaluate the influence of age, gender, puberty, lifestyle factors, and body composition on QUS parameters and to provide a normative database for QUS in school children in Lebanon. Measurements of phalangeal osteosonography were examined in 256 healthy subjects (132 boys and 124 girls) aged 11-18 years using an ultrasound device. In both genders, amplitude-dependent speed of sound (AD-SoS) and bone transmission time (BTT) increased significantly with age and pubertal stages. Girls had higher AD-SoS values than boys between 11 and 15 years of age and at Tanner stages III and IV; however, no differences were detected in the older age groups. AD-SoS and BTT showed a significant positive correlation with age and height in both genders (R = 0.41-0.66, P < 0.01). There was no correlation between physical activity, calcium intake, sun exposure, and any of the QUS parameters in either gender. Weight showed moderate positive correlation with AD-SoS in boys and with BTT in both genders (R = 0.31-0.47, P < 0.01). Lean mass showed significant positive correlation with AD-SoS and BTT (R = 0.2-0.68, P < 0.01) in both genders. Percentage body fat showed significant negative correlation with BTT and AD-SoS in boys (R = -0.25 to -0.37, P < 0.01). In the linear regression analyses, there was a significant negative correlation between percentage fat mass and both AD-SoS and BTT in both genders. In conclusion, QUS parameters of the phalanges in Lebanese children are related to growth variables such as height, age, and puberty in healthy children. The impact and magnitude of body composition variables and lifestyle factors on ultrasonometry derived variables differ from their effect on dual energy X-ray absorptiometry derived parameters.

Genetic and environmental determinants of bone mineral density in Chinese women

BMD is a complex trait determined by genetic and lifestyle factors. To assess the genetic and environmental determinants of BMD in southern Chinese women, we studied a community-based cohort of 531 pre- and postmenopausal southern Chinese women and assessed the influence of 12 candidate gene loci and lifestyle risk factors on spine and hip BMD. The candidate genes studied include estrogen receptor alpha (ESR1) and beta (ESR2), calcium sensing receptor (CASR), vitamin D receptor (VDR), collagen type Ialpha1 (COLIA1), and LDL receptor-related protein 5 (LRP5). Social, medical, reproductive history, dietary habits and lifestyle factors were determined using a structured questionnaire. Single nucleotide polymorphisms (SNPs) of the COLIA1 and LRP5 gene in Chinese were determined by direct sequencing. Nucleotide (nt) -1363C/G and -1997 G/T of COLIA1, nt 266A/G, 2220C/T and 3989C/T of LRP5 gene were analyzed. Using stepwise multiple linear regression analyses, body weight was the strongest predictor for BMD in premenopausal women (n = 262), which accounted for 15.9% of the variance at the spine, 20% at femoral neck, 17.1% at trochanter, 24.3% at total hip and 10.9% at the Ward's triangle. Other significant predictors were ESR1 Ivs1-397T/C genotype (2.2% at the spine); LRP5 2220C/T genotype (1.3% at the spine, 1.6% at the trochanter); LRP5 266A/G genotype (1.1% at Ward's triangle); age at menarche (1.3% at trochanter) and age (2.0% at Ward's triangle). As for postmenopausal women (n = 269), body weight ( approximately 25% at various sites) and age (approximately 16% at femoral neck, trochanter, total hip and Ward's triangle sites) were the strongest predictors of BMD. Other significant predictors were age at menarche (4.4% at spine, 0.7% at femoral neck, 1.4% at trochanter, and 1.4% at Ward's triangle); weight bearing physical activity (2.1% at trochanter and 1% at total hip); calcium intake (1.1% at femoral neck, 0.9% at trochanter, and 1.7% at total hip) ; height (0.7% at trochanter); and ESR2 1082A/G genotype (0.8% at trochanter). We conclude that BMD at various sites and at different time span of a woman is modified by different genetic and lifestyle factors, suggesting that BMD is highly dependent on gene-environmental interactions.

Positive, site-specific associations between bone mineral status, fitness, and time spent at high-impact activities in 16- to 18-year-old boys

The incidence of hip and forearm fracture in elderly men in the United Kingdom is a public health issue, but there is limited knowledge on lifestyle factors affecting male bone health. The aim of this cross-sectional study was to evaluate the relationships between whole body and regional bone mineral status and self-reported participation time in no-, low-, moderate-, and high-impact activities and fitness measurements in 16- to 18-year-old boys. One hundred twenty-eight boys underwent absorptiometry (DXA) measurements (Hologic QDR 1000W) of bone mineral content (BMC), bone area (BA), and bone mineral density (BMD) at the whole body, hip, spine, and forearm. They also completed the EPIC (European Prospective Investigation of Cancer) physical activity questionnaire, which allowed categorization of activities according to impact and aerobic intensity. Fitness and strength were assessed in each subject using estimated VO2 max, grip strength, and back strength. Significant positive relationships were found between BMC, BA, and BMD and the fitness and strength measurements and participation time in high-impact sports at most skeletal sites. The relationships were further examined after adjustment of BMC for height, weight, and bone area, thereby minimizing the influence of body and bone size on these relationships. VO2 max was a significant positive determinant of size-adjusted BMC at the whole body, the ultradistal and one-third radius, and all the hip sites, except the trochanter. Size-adjusted BMC at the forearm sites and trochanter was significantly positively associated with grip strength. Size-adjusted BMC at the whole body and all the hip sites was significantly positively associated with time spent at high-impact activities. Differences in size-adjusted BMC across thirds of time spent at high-impact activities were also examined. Boys in the highest third of high-impact activity had significantly greater size-adjusted whole body BMC and total hip BMC compared to subjects in the lowest third [+3.4 (1.2)% for whole body and +8.5 (2.2)% for hip, both P = 0.001]. Boys in the highest third of high-impact activity spent most activity time jogging, playing tennis, football and rugby, basketball, and exercising with weights. Back strength and lean mass were significantly greater in subjects in the highest third compared to those in the middle (P = 0.02) and lowest third (P = 0.03). No significant differences were found between subjects in each third of high-impact activity for potential confounders including TV viewing, calcium intake, body fat, and height. These findings indicate that participation of male adolescents in a range of high-impact activities for 1 h or more a day is associated with greater bone size and mineral content, especially at the hip.

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.

Sex differences in the effect of body-composition variables on bone mass in healthy children and adolescents

BACKGROUND

Prophylactic interventions against osteoporosis require a determination of the factors that influence the accumulation of bone mass during growth.

OBJECTIVE

The objective was to determine the independent sex-specific contribution of lean mass and fat mass to bone mineral content (BMC), after adjustment for anthropometric variables and lifestyle factors, in healthy children and adolescents.

DESIGN

Healthy schoolchildren (184 boys and 179 girls) aged 10-17 y (x+/- SD: 13.0 +/- 2.1 y) participated in this cross-sectional study. Total and regional (lumbar spine, femoral neck, and distal one-third of the radius) BMC and body composition were measured by dual-energy X-ray absorptiometry.

RESULTS

A significant effect of anthropometric variables and lifestyle factors on BMC was observed at all skeletal sites. Lean mass and fat mass showed robust correlations with BMC, even after adjustment for anthropometric variables and lifestyle factors. Lean mass contributed to 6-12% of the variance in BMC in boys and to 4-10% in girls. Fat mass accounted for 0.1-2% of BMC variance in boys and to 0.1-6.5% in girls.

CONCLUSIONS

Both lean mass and fat mass are consistent predictors of BMC at multiple skeletal sites in healthy children and adolescents. The contribution of lean mass to BMC variance was larger in boys than in girls. In both sexes, the highest contribution of lean mass to BMC was observed at the femoral neck.

Bone turnover during inpatient nutritional therapy and outpatient follow-up in patients with anorexia nervosa compared with that in healthy control subjects

BACKGROUND

Osteopenia and osteoporosis are among the most frequent and severe complications in adolescents with anorexia nervosa.

OBJECTIVE

The aim of this study was to assess the influence of nutritional therapy on bone metabolism during adolescent anorexia nervosa.

DESIGN

We studied 19 anorectic patients aged 14.1 +/- 1.4 y (x +/- SD) with a body mass index (BMI; in kg/m(2)) of 14.2 +/- 1.4 and 19 age-matched control subjects aged 15.1 +/- 2.3 y with a BMI of 20.8 +/- 1.9 for 1 y. Blood samples were taken for the measurement of bone markers, insulin-like growth factor I (IGF-I), and leptin.

RESULTS

BMI rose significantly from 14.2 +/- 1.4 at baseline to 17.4 +/- 0.6 (P < 0.0001) at week 15. Compared with concentrations in the control subjects, concentrations of the bone formation markers procollagen type I propeptide (PICP) and bone alkaline phosphatase (bAP) in the anorectic patients were lower at baseline (PICP: P = 0.0071; bAP: P = 0.0012), increased with nutritional therapy (PICP: P = 0.0060, bAP: P = 0.0147), and were no longer significantly different (P > 0.05) during the follow-up period. Concentrations of IGF-I and leptin were significantly lower (P < 0.0001 for both) in the anorectic patients than in the control subjects at baseline. IGF-I increased with nutritional therapy but was still significantly lower (P = 0.0036) than that in the control group and decreased again during the follow-up period (P = 0.0126). In contrast, serum C-telopeptide decreased with nutritional therapy (P = 0.0446).

CONCLUSION

Nutritional therapy improves concentrations of bone formation markers in adolescent patients with anorexia nervosa.

Normal annual increase of bone mineral density during two years in patients with cystic fibrosis

OBJECTIVES

To determine prospectively for 2 years the change in bone mineral density (BMD) in patients with cystic fibrosis (CF) and to correlate clinical data and routine biochemical parameters of bone metabolism and infection with BMD.

METHODS

Fifty-four patients with CF, aged 6 to 33 years, were included. BMD was measured using dual-energy x-ray absorptiometry in lumbar spine (LS) and femoral neck (FN). Anthropometric data and biochemical markers of bone metabolism and infection were measured. The number of intravenous antibiotic courses per year (ivAC) and pulmonary function were assessed.

RESULTS

The patients had normal anthropometric data and normal growth, but 36% and 33% of the patients had BMD z score <-1 standard deviation in LS and in FN, respectively. Nevertheless, BMD increased at a normal rate during the 2 years and was correlated to weight and lung function. Intact parathyroid hormone was positively correlated with the increase of BMD in both LS and FN during childhood. Blood sedimentation rate, serum concentration of immunoglobulin G, and ivAC were negatively correlated with BMD in FN. Patients with 2 more severe CF transmembrane conductance regulator mutations had significantly lower BMD in FN than other genetic combinations.

CONCLUSION

The study suggests that low BMD in CF is multifactorial and depends on infection and nutritional parameters. Differences in BMD of LS and FN suggested higher susceptibility to infection in FN at all ages. Longitudinal studies starting early before bacterial colonization would be valuable to determine the relative role of infection in the development of BMD in CF.

Body composition and bone measurements in intra-uterine growth retarded and early postnatally undernourished male and female rats at the age of 6 months: comparison with puberty

Undernutrition in early life may permanently change body structure, physiology and metabolism and leads to chronic diseases in later life. To test whether malnutrition during different critical time periods around birth in the rat has long-lasting effects on body composition and skeletal growth, we examined body weight and body composition in pubertal rats and adult rats of 6 months after pre- and postnatal malnutrition. Prenatal malnutrition or intra-uterine growth retardation (IUGR) was induced by ligation of the uterine arteries on day 17 of gestation and postnatal food restriction (FR) by litter enlargement to 20 pups per mother from day 2 after birth until weaning (day 24). Pubertal markers were balanopreputial separation (BPS) in the male and vaginal opening (VO) in the female. IUGR as well as FR resulted in a persistent growth retardation. From birth in IUGR rats and from day 4 after birth in FR rats until 6 months of age body weight in male and female rats was significantly lower compared with controls (P < 0.01 and P < 0.05). Although total body bone mineral content (TBBMC) did not differ between male IUGR rats and controls at BPS, at the age of 6 months TBBMC was significantly lower (P < 0.01) compared with controls. At BPS as well as at 6 months of age, TBBMC was significantly lower in male FR rats compared with controls (P < 0.05 and P < 0.01). In the female IUGR rats TBBMC was significantly lower compared with controls at VO (P < 0.01) and 6 months (P < 0.05). TBBMC in the female FR rats was significantly lower at VO (P < 0.01), but did not differ from controls at the age of 6 months. For both IUGR and FR male and female rats these differences disappeared after adjusting for body weight. Body composition in terms of total fat mass, percentage fat and percentage lean did not differ from controls in male and female IUGR rats at 6 months and the same results were observed in the female FR rats. However, in the male FR rats, total fat mass and percentage fat were significantly lower compared with controls (P < 0.01 and P < 0.05), while the percentage lean mass was significantly higher (P < 0.05). We conclude that different critical time periods of malnutrition around birth have different effects later in life on growth, which do not disappear at least after 6 months of life. With respect to body composition, only in the FR male rats, differences are found in total fat mass and the balance of percentage fat mass and lean mass. At time of puberty and at the age of 6 months bone mass adjusted for body weight does not seem to be affected by perinatal undernutrition.

Environmental and behavioral factors are associated with the calcium intake of low-income adolescent girls

Based on social cognitive theory, the purpose of this study was to determine whether selected environmental and behavioral factors were associated with the calcium intake of low-income adolescent girls. Teachers in three public middle schools administered a written survey resulting in data from 105 girls (the majority were Asian American). Calcium intake was lower than recommended and was associated with eating breakfast, number of children in the household, availability of some high-calcium foods, and seeing important others drink milk or being encouraged to drink milk. Educational interventions should be targeted to parents in relation to making affordable sources of calcium available and modeling adequate intake to adolescents.

Increasing fluid milk favorably affects bone mineral density responses to resistance training in adolescent boys

This study examined the effects of increasing milk on bone and body composition responses to resistance training in adolescents. Twenty-eight boys (13 to 17 years of age) were randomly assigned to consume, in addition to their habitual diet, 3 servings/day of 1% fluid milk (n=14) or juice not fortified with calcium (n=14) while engaged in a 12-week resistance-training program. For all subjects combined, there were significant (P<or=.05) changes in height (+0.5%), sigmaseven skin folds (-7.7%), body mass (+2.6%), lean body mass (+5.1%), fat mass (-9.3%), whole-body bone mineral content (+3.6%), bone mineral density (+1.8%), and maximal strength in the squat (+43%) and bench press (+23%). Compared with juice, the milk group had a significantly greater increase in bone mineral density (0.014 vs 0.028 g/cm(2)). Increasing intake of milk in physically active adolescent boys may enhance bone health.