Maximizing bone mineral mass gain during growth for the prevention of fractures in the adolescents and the elderly

Cycling and bone health: a systematic review

BACKGROUND

Cycling is considered to be a highly beneficial sport for significantly enhancing cardiovascular fitness in individuals, yet studies show little or no corresponding improvements in bone mass.

METHODS

A scientific literature search on studies discussing bone mass and bone metabolism in cyclists was performed to collect all relevant published material up to April 2012. Descriptive, cross-sectional, longitudinal and interventional studies were all reviewed. Inclusion criteria were met by 31 studies.

RESULTS

Heterogeneous studies in terms of gender, age, data source, group of comparison, cycling level or modality practiced among others factors showed minor but important differences in results. Despite some controversial results, it has been observed that adult road cyclists participating in regular training have low bone mineral density in key regions (for example, lumbar spine). Conversely, other types of cycling (such as mountain biking), or combination with other sports could reduce this unsafe effect. These results cannot yet be explained by differences in dietary patterns or endocrine factors.

CONCLUSIONS

From our comprehensive survey of the current available literature it can be concluded that road cycling does not appear to confer any significant osteogenic benefit. The cause of this may be related to spending long hours in a weight-supported position on the bike in combination with the necessary enforced recovery time that involves a large amount of time sitting or lying supine, especially at the competitive level.

A milk and cereal dietary pattern is associated with a reduced likelihood of having a low bone mineral density of the lumbar spine in Korean adolescents

The traditional rice-based Korean diet has been changing toward a Western-style diet. This change has been especially rapid among adolescents. The purpose of this study was to investigate the association between dietary patterns and bone health among Korean adolescents. This cross-sectional study was conducted on 196 adolescents aged 12 to 15 years. Information on the general characteristics of the subjects was obtained through a questionnaire, and dietary intake was assessed with 6-day food records. Bone mineral densities (BMDs) of the lumbar spine and femur were measured by dual-energy x-ray absorptiometry. Dietary patterns were derived from 24 food groups using factor analysis. Four distinct dietary patterns-traditional Korean, fast food, milk and cereal, and snacks-were identified and accounted for 28.4% of the total variance. After adjusting for sex, age, body mass index percentiles, weight loss attempts, pubertal status, and regular exercise, the adolescents in the highest tertile of the "milk and cereal" dietary pattern score had significantly a reduced likelihood of having low BMD compared with those in the lowest tertile of this diet at the lumbar spine (odds ratio, 0.36; 95% confidence interval, 0.14-0.93; P = .0461). The other dietary patterns were not associated with the BMD of Korean adolescents. These results indicate that the intake of milk and cereal is important for the bone health of Korean adolescents, whose diets are composed mainly of grains and vegetables.

Osteoporosis in young adults: pathophysiology, diagnosis, and management

Postmenopausal osteoporosis is mainly caused by increased bone remodeling resulting from estrogen deficiency. Indications for treatment are based on low areal bone mineral density (aBMD, T-score  ≤ -2.5), typical fragility fractures (spine or hip), and more recently, an elevated 10-year fracture probability (by FRAX®). In contrast, there is no clear definition of osteoporosis nor intervention thresholds in younger individuals. Low aBMD in a young adult may reflect a physiologically low peak bone mass, such as in lean but otherwise healthy persons, whereas fractures commonly occur with high-impact trauma, i.e., without bone fragility. Furthermore, low aBMD associated with vitamin D deficiency may be highly prevalent in some regions of the world. Nevertheless, true osteoporosis in the young can occur, which we define as a T-score below -2.5 at spine or hip in association with a chronic disease known to affect bone metabolism. In the absence of secondary causes, the presence of fragility fractures, such as in vertebrae, may point towards genetic or idiopathic osteoporosis. In turn, treatment of the underlying condition may improve bone mass as well. In rare cases, a bone-specific treatment may be indicated, although evidence is scarce for a true benefit on fracture risk. The International Osteoporosis Foundation (IOF) convened a working group to review pathophysiology, diagnosis, and management of osteoporosis in the young, excluding children and adolescents, and provide a screening strategy including laboratory exams for a systematic approach of this condition.

Vitamin C and zinc intakes are related to bone macroarchitectural structure and strength in prepubescent girls

The extent to which nutrient intake may influence bone structure and strength during maximal rates of skeletal growth remains uncertain. We examined the relationship of dietary intake of micronutrients and bone macroarchitectural structure in young girls. This cross-sectional analysis included baseline data from 363 fourth- and sixth-grade girls enrolled in the Jump-In study. Nutrient intake was assessed using the Harvard Youth/Adolescent Food Frequency Questionnaire. Volumetric BMD (vBMD), bone geometry, and strength were measured by peripheral quantitative computed tomography. Correlations and regression modeling assessed relations between usual nutrient intake and bone parameters. In fourth-grade girls, metaphyseal and diaphyseal area and circumferences as well as diaphyseal strength were associated with vitamin C intake (r = 0.15-0.19, p < 0.05). Zinc intake was correlated with diaphyseal vBMD (r = 0.15-0.16, p < 0.05). Using multiple linear regression to adjust for important covariates, we observed significant independent associations for vitamin C and zinc with bone parameters. For every milligram per day of vitamin C intake trabecular area increased by 11 %, cortical strength improved by 14 %, and periosteal and endosteal circumferences increased by 5 and 8.6 %, respectively. For every milligram per day of zinc intake, cortical vBMD increased by <1 %. No significant associations were observed in sixth-grade girls. Results of this study suggests that vitamin C and zinc intake are positively associated with objective measures of bone geometry, size, and strength in fourth-grade girls. This indicates that potential differences in micronutrient and bone associations at various age-associated stages of bone maturation may be indicative of competing hormonal influences.

Densidade mineral óssea associada a características físicas e estilo de vida em adolescentes

INTRODUÇÃO: No Brasil, ainda são poucos os estudos que apresentam dados relevantes sobre fatores relacionados às características físicas ou estilo de vida e a densidade mineral óssea (DMO) de adolescentes do sexo feminino. OBJETIVO: Identificar e verificar a contribuição das características físicas e de estilo de vida relacionadas à DMO de adolescentes do sexo feminino. MÉTODOS: A amostra deste estudo foi composta por 329 meninas com idades entre 10 e 20 anos. Como características físicas, foram avaliados: peso corporal, estatura, índice de massa corporal, estágio de maturação sexual, raça e pigmentação cutânea. Já para o estilo de vida, os seguintes fatores foram avaliados: consumo diário de cálcio, nível de atividade física (NAF) e nível socioeconômico (NSE). A densidade mineral óssea (DMO) do corpo inteiro, da coluna lombar e do colo do fêmur foram avaliados pela densitometria óssea. As relações existentes entre variáveis dependentes e independentes foram avaliadas pela correlação de Pearson (r) e regressão múltipla Stepwise (p < 0,05). RESULTADOS: A DMO dos três sítios ósseos tende a aumentar conforme o aumento do peso corporal, estatura, IMC, idade e estágio de maturação sexual (r ≥ 0,43; p < 0,01). Por outro lado, somente o NAF (r = 0,12; p < 0,05) e o NSE (r = 0,14; p < 0,05) correlacionaram-se positivamente com a DMO. O peso corporal, estágio de maturação sexual, idade, consumo de cálcio, NSE e NAF explicaram de 48 a 68% da variação da DMO das adolescentes. CONCLUSÃO: Os resultados sugerem que a utilização de critérios como peso corporal, idade e maturação sexual sejam os mais indicados para controlar as variações da DMO de adolescentes do sexo feminino. Além disso, o NSE, o NAF e o consumo diário de cálcio possuem uma pequena participação na variação da DMO das adolescentes quando comparados com as características físicas.

Vitamin D status in pediatric patients with a history of malignancy

BACKGROUND

Multiple studies associate low vitamin D levels with cancer morbidity and mortality. However, few studies have measured vitamin D in pediatric patients with malignancy. Our aim was to assess vitamin D status in a large cohort of pediatric patients with cancer and to define risk factors for deficiency.

METHODS

Circulating 25-hydroxyvitamin D (25OHD) levels were measured in 211 patients. Calcium intake and sun exposure habits were assessed in 142 patients (age 12.1 ± 5.8 y; number of male patients, 69; mean time from diagnosis, 4.4 ± 3.8 y).

RESULTS

Daily calcium intake was 66.2 ± 39.3% of the recommended daily allowance. Mean 25OHD levels were 20.6 ± 7.9 ng/ml. Vitamin D deficiency (<15 ng/ml) was found in 24.6% of the patients and insufficiency (15-20 ng/ml) in 23.2%. Younger age and amount of sun exposure were associated with higher serum 25OHD. No association was found with calcium intake, disease type, gender, BMI SD score, years since diagnosis, or stem cell transplantation. The 25OHD levels during winter were significantly lower than the summer levels.

CONCLUSION

The prevalence of vitamin D deficiency and insufficiency in pediatric patients with a history of malignancy was high, whereas calcium intake was low. These findings are concerning, given the risk for osteoporosis in this population and the possible role of vitamin D in the context of malignancy.

Prevalence of vitamin D insufficiency in Swiss teenagers with appendicular fractures: a prospective study of 100 cases

BACKGROUND

The significance of subclinical vitamin D deficiency in the pathogenesis of fractures in children and adolescents currently remains unclear.

OBJECTIVE

We aimed to determine the prevalence of vitamin D insufficiency and its effect on bone mineral density (BMD) and bone mineral content (BMC) values in a collective of Swiss Caucasian children with a first episode of appendicular fracture.

DESIGN AND METHODS

One hundred teenagers with a first episode of appendicular fracture [50 upper limb fractures (group 1) and 50 lower limb fractures (group 2)] and 50 healthy controls (group 3) were recruited into a cross-sectional study. The BMC and BMD values were measured by dual-energy X-ray absorptiometry, and serum 25 hydroxyvitamin D [25(OH)D] was assessed by electrochemiluminescence immunoassays.

RESULTS

From the 100 injured teenagers in the study, 12 % had deficient vitamin D levels (<20 ng/mL; <50 nmol/L) and 36 % had insufficient levels (≥20 <30 ng/mL; ≥50 <78 nmol/L), whereas 6 and 34 % of healthy controls were, respectively, vitamin D deficient and insufficient. There were no significant differences for serum 25(OH)D levels, L2-L4 BMD Z-score, and L2-L4 BMC Z-score variables (p = 0.216) between the three groups nor for the calcaneal BMD Z-score variables (p = 0.278) between healthy controls and lower limb fracture victims. Investigations on the influences of serum 25(OH)D on BMD and BMC showed no correlation between serum 25(OH)D and L2-L4 BMD Z-scores (r = -0.15; p = 0.135), whereas low but significant inverse correlations were, surprisingly, detected between serum 25(OH)D and calcaneal BMD Z-scores (r = -0.21; p = 0.034) and between serum 25(OH)D and L2-L4 BMC Z-scores (r = -0.22; p = 0.029).

CONCLUSIONS

A significant proportion of Swiss Caucasian teenagers were vitamin D insufficient, independent of limb fracture status, in our study. However, this study failed to show an influence of low vitamin D status on BMD and/or BMC of the lumbar spine and heel.

Sedentary behaviours and its association with bone mass in adolescents: the HELENA Cross-Sectional Study

Background

We aimed to examine whether time spent on different sedentary behaviours is associated with bone mineral content (BMC) in adolescents, after controlling for relevant confounders such as lean mass and objectively measured physical activity (PA), and if so, whether extra-curricular participation in osteogenic sports could have a role in this association.

Methods

Participants were 359 Spanish adolescents (12.5-17.5 yr, 178 boys,) from the HELENA-CSS (2006–07). Relationships of sedentary behaviours with bone variables were analysed by linear regression. The prevalence of low BMC (at least 1SD below the mean) and time spent on sedentary behaviours according to extracurricular sport participation was analysed by Chi-square tests.

Results

In boys, the use of internet for non-study was negatively associated with whole body BMC after adjustment for lean mass and moderate to vigorous PA (MVPA). In girls, the time spent studying was negatively associated with femoral neck BMC. Additional adjustment for lean mass slightly reduced the negative association between time spent studying and femoral neck BMC. The additional adjustment for MVPA did not change the results at this site. The percentage of girls having low femoral neck BMC was significantly smaller in those participating in osteogenic sports (≥ 3 h/week) than in the rest, independently of the cut-off selected for the time spent studying.

Conclusions

The use of internet for non-study (in boys) and the time spent studying (in girls) are negatively associated with whole body and femoral neck BMC, respectively. In addition, at least 3 h/week of extra-curricular osteogenic sports may help to counteract the negative association of time spent studying on bone health in girls.

Influence of birth weight on calcaneal bone stiffness in Belgian preadolescent children

The aim of this study was to investigate the relation between birth weight and calcaneal bone stiffness in a large sample of Belgian, healthy, preadolescent children. Participants were 827 children (3.6-11.2 years, 51.6 % boys) from the Belgian cohort of the IDEFICS study. Birth weight was obtained using a parental questionnaire, and quantitative ultrasound (QUS) measurements were performed to determine calcaneal broadband ultrasound attenuation (BUA), speed of sound (SOS), and stiffness index (SI) using the Lunar Achilles device. Average birth weights were 3435.7 ± 512.0 g for boys and 3256.9 ± 471.1 g for girls. Average calcaneal QUS measurements were 89.6 ± 24.0 (23.3-153.9) dB/MHz for BUA, 1621.4 ± 49.6 (1516.3-1776.5) m/s for SOS, and 92.8 ± 15.6 (49.0-163.0) for SI. Birth weight was positively associated with BUA (r = 0.13, p = 0.002) and SOS (r = -0.16, p < 0.001). The associations remained after correcting for age and sex in multiple regression analyses but disappeared after correcting for anthropometric covariates. Our findings suggest that birth weight, as a rough proxy indicator for genetic and environmental influences during intrauterine life, is associated with BUA and SOS in preadolescent children and may therefore influence the risk of osteoporosis later in life. Further studies using QUS are needed to investigate the consistency of the results of this study.

Relationship between markers of body fat and calcaneal bone stiffness differs between preschool and primary school children: results from the IDEFICS baseline survey

The aim of this study was to investigate the relationship between markers of body fat and bone status assessed as calcaneal bone stiffness in a large sample of European healthy pre- and primary school children. Participants were 7,447 children from the IDEFICS study (spread over eight different European countries), age 6.1 ± 1.8 years (range 2.1-9.9), 50.5 % boys. Anthropometric measurements (weight, height, bioelectrical impedance, waist and hip circumference, and tricipital and subscapular skinfold thickness) as well as quantitative ultrasonographic measurements to determine calcaneal stiffness index (SI) were performed. Partial correlation analysis, linear regression analysis, and ANCOVA were stratified by sex and age group: preschool boys (n = 1,699) and girls (n = 1,599) and primary school boys (n = 2,062) and girls (n = 2,087). In the overall study population, the average calcaneal SI was equal to 80.2 ± 14.0, ranging 42.4-153. The results showed that preschool children with higher body fat had lower calcaneal SI (significant correlation coefficients between -0.05 and -0.20), while primary school children with higher body fat had higher calcaneal SI (significant correlation coefficients between 0.05 and 0.13). After adjusting for fat-free mass, both preschool and primary school children showed an inverse relationship between body fat and calcaneal stiffness. To conclude, body fat is negatively associated with calcaneal bone stiffness in children after adjustment for fat-free mass. Fat-free mass may confound the association in primary school children but not in preschool children. Muscle mass may therefore be an important determinant of bone stiffness.

Matrix IGF-1 maintains bone mass by activation of mTOR in mesenchymal stem cells

Insulin-like growth factor 1 (IGF-1), the most abundant growth factor in the bone matrix, maintains bone mass in adulthood. We now report that IGF-1 released from the bone matrix during bone remodeling stimulates osteoblastic differentiation of recruited mesenchymal stem cells (MSCs) by activation of mammalian target of rapamycin (mTOR), thus maintaining proper bone microarchitecture and mass. Mice with knockout of the IGF-1 receptor (Igf1r) in their pre-osteoblastic cells showed lower bone mass and mineral deposition rates than wild-type mice. Further, MSCs from Igf1rflox/flox mice with Igf1r deleted by a Cre adenovirus in vitro, although recruited to the bone surface after implantation, were unable to differentiate into osteoblasts. We also found that the concentrations of IGF-1 in the bone matrix and marrow of aged rats were lower than in those of young rats and directly correlated with the age-related decrease in bone mass. Likewise, in age-related osteoporosis in humans, we found that bone marrow IGF-1 concentrations were 40% lower in individuals with osteoporosis than in individuals without osteoporosis. Notably, injection of IGF-1 plus IGF binding protein 3 (IGFBP3), but not injection of IGF-1 alone, increased the concentration of IGF-1 in the bone matrix and stimulated new bone formation in aged rats. Together, these results provide mechanistic insight into how IGF-1 maintains adult bone mass, while also providing a further rationale for its therapeutic targeting to treat age-related osteoporosis.

Age-related bone mineral density patterns in Koreans (KNHANES IV)

CONTEXT

Bone loss is considered to begin with menopause in women and later in life in men; however, several recent studies have reported that bone loss began in young adults. There are still discordant results concerning age-related changes in bone mineral density (BMD), especially in nonvertebral bone.

OBJECTIVE

The objective of the study was to investigate the age-related changes in BMD in Korean youth.

DESIGN AND SETTING

This was a population-based, cross-sectional study from the Fourth Korea National Health and Nutrition Examination Surveys.

PARTICIPANTS

A total 10,575 Korean (4,731 males and 5,844 females) aged 10-80 yr were included.

MAIN OUTCOME MEASURES

BMD at the spine and hip was measured using dual X-ray absorptiometry.

RESULTS

Age-related bone loss at the femoral neck in males occurred continuously with temporary acceleration phase after achieving peak bone mass (PBM). In contrast, age-related bone loss at total hip in both sexes and femoral neck in females showed three obvious phases: acceleration, consolidation, and then the second acceleration phase after reaching PBM. Interestingly, this pattern of bone loss was more significant in the total hip and thus showed the acceleration phase until the late 20s and the consolidation phase until the late 40s. Early accelerated loss of BMD was not observed at the lumbar spine in each sex. Although body mass index and body fat percentage were more related with BMD than other clinical parameters, they could not explain the early accelerated loss of BMD at the femur.

CONCLUSIONS

There was an accelerated bone loss at the femur in both sexes during early adulthood and more than 60% of the bone loss before age 50 yr occurred during this period.

Validation of a milk consumption stage of change algorithm among adolescent survivors of childhood cancer

OBJECTIVE

To assess the construct validity of a milk consumption Stages of Change (SOC) algorithm among adolescent survivors of childhood cancer ages 11 to 21 years (n = 75).

METHODS

Baseline data from a randomized controlled trial designed to evaluate a health behavior intervention were analyzed. Assessments included a milk consumption SOC algorithm and hypothesized theoretical and behavioral predictors of SOC.

RESULTS

Compared with survivors who expressed no readiness to change, those expressing readiness to change behavior for both 2 and 4 daily servings of milk reported more frequent milk consumption (P < .001), greater dietary calcium intake (P = .006), and were more likely to meet age-specific recommendations for daily calcium intake (P = .01).

CONCLUSIONS AND IMPLICATIONS

Results provide support for the construct validity of the milk consumption SOC algorithm relative to behavioral criteria. Research is needed to further examine algorithm validity with respect to theoretical predictors of SOC.

Vitamin D status and physical activity interact to improve bone mass in adolescents. The HELENA Study

The effects of vitamin D concentrations on bone mineral content in adolescents are still unclear. Vitamin D and physical activity (PA) may interact to determine bone mineral content (BMC) in two possible directions; 25(OH)D sufficiency levels improve BMC only in active adolescents, or PA increases BMC in individuals with replete vitamin D levels.

INTRODUCTION

The effects of suboptimal 25-hydroxycholecalciferol (25(OH)D) concentrations on BMC in adolescents are still unclear. The main aim of this study was to evaluate the influence of 25(OH)D on BMC in adolescents, considering the effect of body composition, sex, age, Tanner stage, season, calcium and vitamin D intakes, physical fitness and PA.

METHODS

Serum 25(OH)D concentrations, anthropometric measurements, dual energy X-ray absorptiometry measurements, calcium and vitamin D intakes, PA and physical fitness were obtained in 100 Spanish adolescents (47 males), aged 12.5-17.5 years, within the framework of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study. Relations were examined using ANCOVA and regression analyses including BMC as dependent variable.

RESULTS

Linear regression of BMC suggested that 25(OH)D concentrations independently influenced total and leg BMC after controlling for age, sex, lean mass, seasonality and calcium intake (B = 0.328, p < 0.05, and B = 0.221, p < 0.05, respectively) in the physically active group. No significant influence of 25(OH)D concentrations on BMC was observed in the inactive group. Significant effect was shown between the interaction of 25(OH)D and PA on BMC for the total body and legs (both p < 0.05).

CONCLUSIONS

Vitamin D and PA may interact to determine BMC. 25(OH)D sufficiency levels improve bone mass only in active adolescents, or PA has a positive influence on BMC in individuals with replete vitamin D levels.

Sexual dimorphism of femoral neck cross-sectional bone geometry in athletes and non-athletes: a hip structural analysis study

The characterisation of bone geometry in male and female athletes may increase our understanding of how physical loading may enhance bone strength in both sexes. This study investigated sexual dimorphism in hip geometry of athletes and age- and sex-matched non-athletes. Dual energy X-ray absorptiometry of the left proximal femur was performed in 62 male (n = 31; 30.2 ± 4.6 years) and female (n = 31; 27.9 ± 5.2 years) competitive endurance runners, and 36 male (n = 18; 28.7 ± 5.8 years) and female (n = 18; 29.1 ± 5.3 years) non-athletes. The hip structural analysis programme determined areal bone mineral density (aBMD), bone area (BA), hip axis length, cross-sectional area (CSA), and cross-sectional moment of inertia (CSMI) of the femoral neck. Strength indices were derived from the femoral strength index (FSI) (Yoshikawa et al., J Bone Miner Res 9:1053-1064, 1994). Despite similar size-adjusted aBMD, sexual dimorphism was apparent for BA, CSA and CSMI, with superior values in men compared to women (P < 0.01). FSI was greater in male and female athletes than non-athletes (P < 0.01). From all groups, results in male athletes inferred greatest resistance to axial (CSA) and bending loads (FSI). Estimates of bone strength (FSI) were greater in female athletes than male and female non-athletes, supporting the osteogenic value of regular loading of the hip.

School-based calcium-vitamin D with micronutrient supplementation enhances bone mass in underprivileged Indian premenarchal girls

Low adult bone mass is linked to osteoporosis and fractures and is dependent on the extent of childhood and adolescent bone mineralization. The aim of the study was to investigate the effect of 1-year supplementation of calcium, multivitamin with zinc along with vitamin-D on bone mass accrual of school-going premenarchal girls from low income groups in Pune, India. Double-blind, matched-pair, cluster, randomization study was carried out in 214 premenarchal girls (8-12 years) from 2 schools in Pune, India. The two schools together formed 3 classes with 3 clusters each of age-matched girls of which one cluster was allocated to either one of the intervention groups (Ca-group:500 mg/d calcium, Ca+MZ-group:500 mg/d calcium+multivitamin tablet containing 15 mg/d zinc) or control group (C-group: multivitamin tablet without any minerals); all subjects received vitamin-D supplementation. Anthropometry, biochemical parameters, total body bone mineral content (TBBMC) and bone mineral density (TBBMD) (Dual energy X-ray absorptiometry) were assessed at baseline and endline. Post supplementation, mean percent increase in TBBMC was significantly higher in Ca-group (22.3%) and Ca+MZ-group (20.8%) compared to C-group (17.6%) (p<0.05) with no significant differences observed between Ca+MZ and Ca groups (p>0.1). Improvement in TBBMC-for-age Z-scores was higher in the two calcium supplemented groups (13.6%-22%) compared to the C-group (no improvement). Calcium supplementation, with or without multivitamins and zinc, showed a promising improvement in bone health especially with regards to improvement in bone related Z-scores in our population of underprivileged premenarchal girls.

A 21-week bone deposition promoting exercise programme increases bone mass in young people with Down syndrome

AIM

To determine whether the bone mass of young people with Down syndrome may increase, following a 21-week conditioning training programme including plyometric jumps.

METHOD

Twenty-eight participants with Down syndrome (13 females, 15 males) aged 10 to 19 years were divided into exercise (DS-E; n=14; eight females, six males mean age 13y 8mo, SD 2y 6mo) and non-exercise (DS-NE; n=14; five females, nine males mean age 15y 5mo, SD 2y 6mo) groups. Total and regional (hip and lumbar spine [L1-L4]) bone mineral content (BMC) and total lean mass were assessed by dual energy X-ray absorptiometry at baseline and after a 25-minute training session performed twice a week. Repeated-measures analyses of variation were applied to test differences between pre- and posttraining values for BMC and total lean mass. Differences between increments were studied with the Student's t-test. Linear regression models were fitted to test independent relationships.

RESULTS

After the intervention, higher increments in total and hip BMC, and total lean mass, were observed in the DS-E group (all p<0.05). A time × exercise interaction was found for total lean mass (p<0.05). The increment in total lean mass, height, and Tanner stage accounted for almost for 60% in the increment in total BMC in the DS-NE group (p<0.05).

INTERPRETATION

Twenty-one weeks of training have a positive effect on the acquisition of bone mass in young people with Down syndrome.

[Impact of physical activity and exercise on bone health in the life course : a review]

Physical activity and exercise are important determinants for metabolic and cardiovascular health. They also play an important role for bone health in childhood, adolescence, and adulthood. This review summarizes results from observational and intervention studies which evaluated the association between physical activity/exercise and bone health in different life course stages. In childhood and adolescence, physical activity and exercise induce improved bone accrual. In adulthood, mainly in postmenopausal women, long-term exercise programs reduce age-related bone loss. Especially weight-bearing activities seem to have an important osteogenic effect. Children and adolescent show a higher bone accrual until 5 years after cessation of an exercise program compared to their peers, who do not participate in an exercise program. In contrast, adults who quit exercising have a higher decrease in bone stiffness compared to adults who never exercised. This effect was particularly seen in postmenopausal women. Continuous physical activity and exercise over the life course and the implementation of exercise programs in schools and community-based intervention programs can help prevent or even reduce osteoporosis and osteoporosis-related fractures. Due to the lack of prospective longitudinal studies, the supposed long-term sustainable protective effect of physical activity and exercise in childhood and adolescent on bone health in later adulthood is not well established.

Socioeconomic status and bone mass in Spanish adolescents. The HELENA Study

PURPOSE

Socioeconomic status (SES) has been frequently associated with body composition, particularly fat mass and obesity. However, the SES-bone mass association is not clear. We aimed to evaluate the associations between different SES indicators (Family Affluence Scale, parental education, and occupation) and bone mineral content in Spanish adolescents.

METHODS

Participants were 322 adolescents (164 boys and 158 girls, 12.5-17.5 years) from the Healthy Lifestyle in Europe by Nutrition in Adolescence study. The social background of the adolescents was self-reported using an SES questionnaire, and the bone variables were measured using dual-energy x-ray absorptiometry. Physical activity was measured using accelerometers. Calcium intake was estimated from two nonconsecutive 24 hours recalls. One-way analysis of covariance was performed to examine the relationships between SES indicators and bone mass using different sets of confounders: basic model (sex + sexual maturation), model 1 (basic model + height), model 2 (basic model + lean mass), and model 3 (basic model + calcium intake + average physical activity).

RESULTS

Adjusted results showed no association between SES indicators and whole-body or total hip bone mineral content. Additional analyses were performed in lumbar spine, pelvis, and hip subregions (femoral neck, trochanter, and intertrochanter), and no significant associations were observed at these sites either.

CONCLUSIONS

Our data do not support a link between different SES indicators (Family Affluence Scale, parental education, and occupation) and bone mass in adolescents.

Consumption of vitamin D-and calcium-fortified soft white cheese lowers the biochemical marker of bone resorption TRAP 5b in postmenopausal women at moderate risk of osteoporosis fracture

The prevention of increased bone remodeling in postmenopausal women at low 10-y risk of osteoporotic fractures essentially relies on reinforcement of environmental factors known to positively influence bone health, among which nutrition plays an important role. In institutionalized women in their mid-eighties, we previously found that consumption of fortified soft plain cheese increased vitamin D, calcium, and protein intakes, reduced bone resorption biochemical markers, particularly the serum bone specific acid phosphatase tartrate resistant acid phosphatase, isoform 5b (TRAP 5b) that reflects osteoclast activity, and stimulated the serum bone anabolic factor insulin-like growth factor-I (IGF-I). Whether these effects occur in much younger women was tested in a prospective control study. Seventy-one healthy postmenopausal women aged 56.6 ± 3.9 y (mean ± SD) with low spontaneous supply of both Ca and vitamin D were randomized to consume daily (treated, n = 36) or not (controls, n = 35) two servings (2 × 100 g) of skimmed-milk, soft plain cheese for 6 wk. The vitamin D and Ca-fortified dairy product provided daily: 661 kJ, 2.5 μg vitamin D, 400 mg calcium, and 13.8 g protein. At the end of the intervention, the decrease in TRAP 5b and the increase in IGF-I were greater in the treated than in the control group (P < 0.02). The changes in serum carboxy terminal crosslinked telopeptide of type I collagen did not differ significantly between the two groups. In conclusion, like in elderly women, consumption by healthy postmenopausal women of a vitamin D and calcium-fortified dairy product that also increases the protein intake, reduces the serum concentration of the bone resorption biomarker TRAP 5b. This response, combined with the increase in serum IGF-I, is compatible with a nutrition-induced reduction in postmenopausal bone loss rate.

Effects of vitamin K on the morphometric and material properties of bone in the tibiae of growing rats

Suboptimal vitamin K nutriture is evident during rapid growth. We aimed to determine whether vitamin K(2) (menaquinone-4 [MK-4]) supplementation is beneficial to bone structure and intrinsic bone tissue properties in growing rats. Male Wistar rats (5 weeks old) were assigned to either a control diet (n = 8) or an MK-4-supplemented diet (22 mg d(-1) kg(-1) body weight, n = 8). After a 9-week feeding period, we determined the serum concentration ratio of undercarboxylated osteocalcin to γ-carboxylated osteocalcin and the urinary deoxypyridinoline level. All rats were then euthanized, and their tibiae were analyzed by micro-computed tomography for trabecular architecture and synchrotron radiation micro-computed tomography for cortical pore structure and mineralization. Fourier transform infrared microspectroscopy and a nanoindentation test were performed on the cortical midlayers of the anterior and posterior cortices to assess bone tissue properties. Neither body weight nor tibia length differed significantly between the 2 groups. Dietary MK-4 supplementation decreased the ratio of undercarboxylated osteocalcin to γ-carboxylated osteocalcin but did not affect deoxypyridinoline, indicating a positive effect on bone formation but not bone resorption. Trabecular volume fraction and thickness were increased by MK-4 (P < .05). Neither the cortical pore structure nor mineralization was affected by MK-4. On the other hand, MK-4 increased mineral crystallinity, collagen maturity, and hardness in both the anterior and posterior cortices (P < .05). These data indicate the potential benefit of MK-4 supplementation during growth in terms of enhancing bone quality.

Adiposity and bone health in Spanish adolescents. The HELENA study

While the association of lean mass (LM) with bone mass is well understood, the association of fat mass (FM) with bone mass is controversial. Our results support that adolescents with higher levels of adiposity have greater bone mass, but this association is fully explained by their higher levels of LM.

INTRODUCTION

We aimed (1) to study the independent association of FM and LM with bone mass and (2) to study the differences in bone mass by weight status in adolescents, after controlling for relevant confounders, such as physical activity (PA), calcium intake, and LM.

METHODS

Participants were 330 adolescents (167 boys, 12.5-17.5 years) from the HELENA study. The relationships of FM (DXA, n = 330; BodPod, n = 282) and LM (DXA, n = 330) with different bone variables (whole body, total hip, lumbar spine, and femoral neck) were analyzed by linear regression, and differences between weight status were analyzed by ANCOVA.

RESULTS

Fat mass (DXA) was positively associated with bone variables in both sexes, after adjustment for height, calcium intake, and sexual maturation. Additional adjustment by PA slightly increases the associations. However, adjustment for LM inverted these associations. Similar results were obtained using BodPod instead of DXA for assessing FM. Overweight/obese adolescents had higher BMC than their non-overweight peers in most of regions studied. Additional adjustment for PA slightly increased the differences between weight status groups, while adjusting for LM inverted the associations. LM was strong and positively associated with all bone variables in both sexes. Additional adjustment for PA or FM did not change the results.

CONCLUSIONS

Adolescents with higher levels of adiposity have greater bone mass, but this association is explained by their higher levels of LM.

[Recommended intake of calcium and vitamin D: positioning of the Nutrition Committee of the AEP]

Both calcium and vitamin D are essential nutrients with a crucial role in bone health, although in recent years there has been much controversy about the contributions required from both molecules to ensure adequate health. For vitamin D, in a short time, we have seen how it has gone from a recommendation of 400 IU daily, to 200 IU and again to 400 IU, with some statements that not only its influence on skeletal tissue has been taken into account, but also on the development of chronic diseases, which has led to new expectations. Our goal is to provide an update to paediatricians on this issue and propose recommendations for intake in the light of the latest information. For vitamin D the Committee proposes an intake of 400 IU/day in children under 1 year and 600 IU/day after that age.

Assessment of health claims in the field of bone: a view of the Group for the Respect of Ethics and Excellence in Science (GREES)

Health claims for food products in Europe are permitted if the nutrient has been shown to have a beneficial nutritional or physiological effect. This paper defines health claims related to bone health and provides guidelines for the design and the methodology of clinical studies to support claims.

INTRODUCTION

Regulation (EC) no. 1924/2006 on nutrition and health claims targeting food products was introduced in Europe stating that health claims shall only be permitted if the substance in respect of which the claim is made has been shown to have a beneficial nutritional or physiological effect. The objective of this paper is to define health claims related to bone health and to provide guidelines for the design and the methodology of clinical studies which need to be adopted to assert such health claims.

METHODS

Literature review followed by a consensus discussion during two 1-day meetings organized by the Group for the Respect of Ethics and Excellence in Science (GREES).

RESULTS

The GREES identified six acceptable health claims related to bone health based on the potential of food products to show an effect on either the bioavailability of calcium or osteoclast regulatory proteins or bone turnover markers or bone mineral density or bone structure or fracture incidence. The GREES considers that well-designed human randomized controlled trial on a relevant outcome is the best design to assess health claims. The substantiation of health claim could also be supported by animal studies showing either an improvement in bone strength with the food product or showing the relationship between changes induced by the food product on a surrogate marker and changes in bone strength.

CONCLUSION

The consensus reached is that the level of health claim may differ according to the surrogate endpoint used and on additional animal studies provided to support the claim.

Short-term physical activity intervention decreases femoral bone marrow adipose tissue in young children: a pilot study

Mechanical stimulation is necessary for maximization of geometrical properties of bone mineralization contributing to long-term strength. The amount of mineralization in bones has been reciprocally related to volume of bone marrow adipose tissue and this relationship is suggested to be an independent predictor of fracture. Physical activity represents an extrinsic factor that impacts both mineralization and marrow volume exerting permissive capacity of the growing skeleton to achieve its full genetic potential. Because geometry- and shape-determining processes primarily manifest during the linear growth period, the accelerated structural changes accompanying early childhood (ages 3 to 6 y) may have profound impact on lifelong bone health. The objective of this pilot study was to determine if a short-term physical activity intervention in young children would result in augmentation of geometric properties of bone. Three days per week the intervention group (n=10) participated in 30 min of moderate intensity physical activity, such as jumping, hopping and running, and stretching activities, whereas controls (n=10) underwent usual activities during the 10-week intervention period. Femoral bone marrow adipose tissue volume and total body composition were assessed by magnetic resonance imaging and dual-energy X-ray absorptiometry, respectively, at baseline and after 10 weeks. Although after 10-weeks, intergroup differences were not observed, a significant decrease in femoral marrow adipose tissue volume was observed in those participating in physical activity intervention. Our findings suggest that physical activity may improve bone quality via antagonistic effects on femoral bone marrow adipose tissue and possibly long-term agonistic effects on bone mineralization.

Vitamin D metabolism within bone cells: effects on bone structure and strength

The endocrine activity of 1,25-dihydroxyvitamin D (1,25(OH)(2)D(3)) contributes to maintaining plasma calcium and phosphate homeostasis through actions on the intestine, kidney and bone. A significant body of evidence has been published over the last 10 years indicating that all major bone cells have the capacity to metabolise 25-hydroxyvitamin D (25(OH)D(3)) to 1,25(OH)(2)D(3), which in turn exerts autocrine/paracrine actions to regulate bone cell proliferation and maturation as well as bone mineralisation and resorption. In vivo and in vitro studies indicate that these autocrine/paracrine activities of 1,25(OH)(2)D(3) in bone tissue contribute to maintaining bone mineral homeostasis and enhancing skeletal health.

Plasma adipocytokine and ghrelin levels in relation to bone mineral density in prepubertal rhythmic gymnasts

The aim of the present study was to investigate possible differences in plasma adipocytokine and ghrelin levels and body composition parameters in prepubertal rhythmic gymnasts (RG) and untrained controls (UC), and to examine the relationships of bone mineral density (BMD) with hormonal status in prepubertal children with different physical activity patterns. Eighty-nine 7- to 9-year-old girls participated in the study (RG, n = 46; UC, n = 43). Body composition and BMD were measured by dual-energy X-ray absorptiometry. Bone maturity was estimated by using a radiograph of the nondominant hand. The measured whole-body, lumbar spine (LS), and femoral neck (FN) BMD values were significantly higher (P < 0.05) in gymnasts than in controls. In addition, RG presented significantly lower and higher values (P < 0.05) for leptin and ghrelin concentrations, respectively, in comparison with UC. No differences were observed for adiponectin levels between the studied groups. No relationships between measured BMD values with leptin and ghrelin were observed even after adjustment for age and fat mass (FM) in RG. Whole-body and LS BMD values were significantly correlated with leptin after controlling for age and FM (r = 0.32, P < 0.05) in UC. Femoral neck BMD remained significantly correlated with ghrelin after adjusting for age and FM (r = -0.4, P < 0.05) in UC. No relationships were found between measured BMD values and adiponectin even after controlling for age and FM values in both groups. In conclusion, although all measured BMD values were significantly higher in RG, plasma adipocytokine and ghrelin concentrations were not directly related to bone mineralization in prepubertal RG in contrast to UC.

Human evolution and osteoporosis-related spinal fractures

The field of evolutionary medicine examines the possibility that some diseases are the result of trade-offs made in human evolution. Spinal fractures are the most common osteoporosis-related fracture in humans, but are not observed in apes, even in cases of severe osteopenia. In humans, the development of osteoporosis is influenced by peak bone mass and strength in early adulthood as well as age-related bone loss. Here, we examine the structural differences in the vertebral bodies (the portion of the vertebra most commonly involved in osteoporosis-related fractures) between humans and apes before age-related bone loss occurs. Vertebrae from young adult humans and chimpanzees, gorillas, orangutans, and gibbons (T8 vertebrae, n = 8–14 per species, male and female, humans: 20–40 years of age) were examined to determine bone strength (using finite element models), bone morphology (external shape), and trabecular microarchitecture (micro-computed tomography). The vertebrae of young adult humans are not as strong as those from apes after accounting for body mass (p<0.01). Human vertebrae are larger in size (volume, cross-sectional area, height) than in apes with a similar body mass. Young adult human vertebrae have significantly lower trabecular bone volume fraction (0.26±0.04 in humans and 0.37±0.07 in apes, mean ± SD, p<0.01) and thinner vertebral shells than apes (after accounting for body mass, p<0.01). Since human vertebrae are more porous and weaker than those in apes in young adulthood (after accounting for bone mass), even modest amounts of age-related bone loss may lead to vertebral fracture in humans, while in apes, larger amounts of bone loss would be required before a vertebral fracture becomes likely. We present arguments that differences in vertebral bone size and shape associated with reduced bone strength in humans is linked to evolutionary adaptations associated with bipedalism.

Bone related health status in adolescent cyclists

Purpose

To describe bone status and analyse bone mass in adolescent cyclists.

Methods

Male road cyclists (n = 22) who had been training for a minimum of 2 years and a maximum of 7 years with a volume of 10 h/w, were compared to age-matched controls (n = 22) involved in recreational sports activities. Subjects were divided in 2 groups based on age: adolescents under 17 yrs (cyclists, n = 11; controls, n = 13) and over 17 yrs (cyclists, n = 11; controls, n = 9). Peak oxygen uptake (VO₂max) was measured on a cycloergometer. Whole body, lumbar spine, and hip bone mineral content (BMC), density (BMD) and bone area were assessed using dual x-ray absorptiometry (DXA). Volumetric BMD (vBMD) and bone mineral apparent density (BMAD) were also estimated.

Results

The BMC of cyclists was lower for the whole body, pelvis, femoral neck and legs; BMD for the pelvis, hip, legs and whole body and legs bone area was lower but higher in the hip area (all, P≤0.05) after adjusting by lean mass and height. The BMC of young cyclists was 10% lower in the leg and 8% higher in the hip area than young controls (P≤0.05). The BMC of cyclists over 17 yrs was 26.5%, 15.8% and 14.4% lower BMC at the pelvis, femoral neck and legs respectively while the BMD was 8.9% to 24.5% lower for the whole body, pelvis, total hip, trochanter, intertrochanter, femoral neck and legs and 17.1% lower the vBMD at the femoral neck (all P≤0.05). Grouped by age interaction was found in both pelvis and hip BMC and BMD and in femoral neck vBMD (all P≤0.05).

Conclusion

Cycling performed throughout adolescence may negatively affect bone health, then compromising the acquisition of peak bone mass.

[2011 Up-date of the consensus statement of the Spanish Society of Rheumatology on osteoporosis]

OBJECTIVE

Due to increasing improvement in the diagnosis, evaluation and management of osteoporosis and the development of new tools and drugs, the Spanish Society of Rheumatology (SER) has promoted the development of recommendations based on the best evidence available. These recommendations should be a reference to rheumatologists and other health professionals involved in the treatment of patients with osteoporosis.

METHODS

Recommendations were developed following a nominal group methodology and based on a systematic review. The level of evidence and degree of recommendation were classified according to the model proposed by the Center for Evidence Based Medicine at Oxford. The level of agreement was established through Delphi technique. Evidence from previous consensus and available clinical guidelines was used.

RESULTS

We have produced recommendations on diagnosis, evaluation and management of osteoporosis. These recommendations include the glucocorticoid-induced osteoporosis, premenopausal and male osteoporosis.

CONCLUSIONS

We present the SER recommendations related to the biologic therapy risk management.

Bone mineral density in healthy female adolescents according to age, bone age and pubertal breast stage

Objectives:

This study was designed to evaluate bone mineral density (BMD) in healthy female Brazilian adolescents in five groups looking at chronological age, bone age, and pubertal breast stage, and determining BMD behavior for each classification.

Methods:

Seventy-two healthy female adolescents aged between 10 to 20 incomplete years were divided into five groups and evaluated for calcium intake, weight, height, body mass index (BMI), pubertal breast stage, bone age, and BMD. Bone mass was measured by bone densitometry (DXA) in lumbar spine and proximal femur regions, and the total body. BMI was estimated by Quetelet index. Breast development was assessed by Tanner’s criteria and skeletal maturity by bone age. BMD comparison according to chronologic and bone age, and breast development were analyzed by Anova, with Scheffe’s test used to find significant differences between groups at P≤0.05.

Results:

BMD (g·cm^-2) increased in all studied regions as age advanced, indicating differences from the ages of 13 to 14 years. This group differed to the 10 and 11 to 12 years old groups for lumbar spine BMD (0.865±0.127 vs 0.672±0.082 and 0.689±0.083, respectively) and in girls at pubertal development stage B3, lumbar spine BMD differed from B5 (0.709±0.073 vs 0.936±0.130) and whole body BMD differed from B4 and B5 (0.867±0.056 vs 0.977±0.086 and 1.040±0.080, respectively).

Conclusion:

Bone mineralization increased in the B3 breast maturity group, and the critical years for bone mass acquisition were between 13 and 14 years of age for all sites evaluated by densitometry.

Vitamin D status among adolescents in Europe: the Healthy Lifestyle in Europe by Nutrition in Adolescence study

An adequate vitamin D status is essential during childhood and adolescence, for its important role in cell growth, skeletal structure and development. It also reduces the risk of conditions such as CVD, osteoporosis, diabetes mellitus, infections and autoimmune disease. As comparable data on the European level are lacking, assessment of vitamin D concentrations was included in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study. Fasting blood samples were obtained from a subsample of 1006 adolescents (470 males; 46·8 %) with an age range of 12·5-17·5 years, selected in the ten HELENA cities in the nine European countries participating in this cross-sectional study, and analysed for 25-hydroxycholecalciferol (25(OH)D) by ELISA using EDTA plasma. As specific reference values for adolescents are missing, percentile distribution were computed by age and sex. Median 25(OH)D levels for the whole population were 57·1 nmol/l (5th percentile 24·3 nmol/l, 95th percentile 99·05 nmol/l). Vitamin D status was classified into four groups according to international guidelines (sufficiency/optimal levels ≥ 75 nmol/l; insufficiency 50-75 nmol/l; deficiency 27·5-49·99 nmol/l and severe deficiency < 27·5 nmol/l). About 80 % of the sample had suboptimal levels (39 % had insufficient, 27 % deficient and 15 % severely deficient levels). Vitamin D concentrations increased with age (P < 0·01) and tended to decrease according to BMI. Geographical differences were also identified. Our study results indicate that vitamin D deficiency is a highly prevalent condition in European adolescents and should be a matter of concern for public health authorities.

Lifetime sedentary living accelerates some aspects of secondary aging

Lifetime physical inactivity interacts with secondary aging (i.e., aging caused by diseases and environmental factors) in three patterns of response. First, lifetime physical inactivity confers no apparent effects on a given set of physiological functions. Second, lifetime physical inactivity accelerates secondary aging (e.g., speeding the reduction in bone mineral density, maximal oxygen consumption, and skeletal muscle strength and power), but does not alter the primary aging of these systems. Third, a lifetime of physical activity to the age of ∼60-70 yr old totally prevents decrements in some age-associated risk factors for major chronic diseases, such as endothelial dysfunction and insulin resistance. The present review provides ample and compelling evidence that physical inactivity has a large impact in shortening average life expectancy. In summary, physical inactivity plays a major role in the secondary aging of many essential physiological functions, and this aging can be prevented through a lifetime of physical activity.

Bone mass in male and female children and adolescents with Down syndrome

SUMMARY

Children and adolescents with Down syndrome (DS) have lower levels of bone mass compared with youths without DS. Their sexual dimorphism in bone mass also differs from that observed in children and adolescents without Down syndrome.

INTRODUCTION

This study aimed to compare bone mass and sexual dimorphism in bone mass between male and female youths with DS and age- and sex-matched controls without DS.

METHODS

Bone mineral density (BMD), volumetric BMD, bone mineral apparent density (BMAD), BMD/height (BMDH), and total lean mass were measured or calculated from DXA. Thirty-two youths (15 females) with DS and 32 youths (13 females) without DS participated in the study.

RESULTS

ANOVA tests showed lower BMAD and BMDH in females with DS compared with females without DS. ANCOVA tests revealed lower BMD in the whole body of males and females as well as BMD in the hip region of the females with DS compared with their counterparts without DS. Within the group with DS, females had greater lumbar spine BMD than the males.

CONCLUSIONS

The low values of BMD and related parameters, together with the differences in the sexual dimorphism, indicate a non-standard bone development in this specific population of children and adolescents with DS.

Cortical consolidation due to increased mineralization and endosteal contraction in young adult men: a five-year longitudinal study

CONTEXT

Peak bone mass is an important factor in the lifetime risk of developing osteoporosis. Large, longitudinal studies investigating the age of attainment of site-specific peak bone mass are lacking. OBJECTIVE AND MAIN OUTCOME MEASURES: The main outcome measures were to determine the site-specific development of peak bone mass in appendicular and axial skeletal sites and in the trabecular and cortical bone compartments, using both dual x-ray absorptiometry and peripheral computed tomography.

DESIGN, SETTING, AND POPULATION

In total, 833 men [aged 24.1 ± 0.6 yr (mean ± sd)] from the original population-based Gothenburg Osteoporosis and Obesity Determinants Study (n = 1068) were included in this follow-up examination at 61.2 ± 2.3 months. Areal bone mineral density (aBMD) was measured with dual x-ray absorptiometry, whereas cortical and trabecular volumetric bone mineral density and bone size were measured by peripheral computed tomography at baseline and at the 5-yr follow-up.

RESULTS

During the 5-yr study period, aBMD of the total body, lumbar spine, and radius increased by 3.4, 4.2, and 7.8%, respectively, whereas a decrease in aBMD of the total hip of 1.9% was observed (P < 0.0001). Increments of 2.1 and 0.7% were seen for cortical volumetric bone mineral density of the radius and tibia, respectively (P < 0.0001), whereas cortical thickness increased by 3.8% at the radius and 6.5% at the tibia due to diminished endosteal circumference (radius 2.3% and tibia 4.6%, P < 0.0001).

CONCLUSION

aBMD decreased at the hip but increased at the spine and radius, in which the increment was explained by continued mineralization and augmented cortical thickness due to endosteal contraction in men between ages 19 and 24 yr.

Levels of physical activity that predict optimal bone mass in adolescents: the HELENA study

BACKGROUND

Physical activity is necessary for bone mass development in adolescence. There are few studies quantifying the associations between physical activity and bone mass in adolescents.

PURPOSE

To assess the relationship between moderate-to-vigorous physical activity (MVPA) and vigorous physical activity (VPA) and bone mass in adolescents.

METHODS

Bone mass was measured by dual-energy X-ray absorptiometry and physical activity by accelerometers in 380 healthy Spanish adolescents (189 boys, aged 12.5-17.5 years) from the HELENA-CSS (2006-2007). Subjects were classified according to the recommended amount of MVPA (<60 minutes or ≥60 minutes of MVPA/day). Receiver operating characteristic curve analysis was applied to calculate the relationship between physical activity and bone mass.

RESULTS

Less than 41 and 45 minutes of MVPA/day are associated with reduced bone mass at the trochanter and femoral neck. More than 78 minutes of MVPA/day is associated with increased bone mineral density (BMD) at the femoral neck. Regarding VPA, more than 28 minutes/day for the hip and intertrochanter and more than 32 minutes/day for the femoral neck are associated with increased BMD.

CONCLUSIONS

The recommended amount of physical activity (minutes/day) seems insufficient to guarantee increased bone mass. With some minutes of VPA/day, bone adaptations could be obtained at different bone sites.

Dietary sources and sociodemographic and economic factors affecting vitamin D and calcium intakes in Flemish preschoolers

BACKGROUND/OBJECTIVES

Low calcium and vitamin D intakes have been associated with health risks in childhood and adulthood. This study aims to investigate dietary sources of calcium and vitamin D intake, and its associated sociodemographic, economic and lifestyle factors among preschoolers.

SUBJECTS/METHODS

Three-day estimated diet records from 696 Flemish preschoolers 2.5-6.5 years old (51% boys) were used (66% of 1052 collected diaries). Contribution of 58 food groups to calcium and vitamin D intake were computed. Multiple linear regression was used to examine associations of intakes with sociodemographic, economic and lifestyle factors.

RESULTS

Mean calcium intake (844 mg per day) was above, and mean vitamin D intake (2.0 μg per day) largely below the Belgian recommendations. Milk, sweetened milk drinks and cheese were the main sources of calcium intakes (26, 25 and 11%, respectively). Butter and margarine were the main vitamin D sources (26%), followed by growth milk (=fortified milk) (20%) and fish (15%). Calcium and vitamin D intake were negatively associated with participants' age, and calcium positively with parental education and family size. The child's gender, supplement use and physical activity level, and the employment status and smoking behaviour of the parents were not associated with calcium or vitamin D intake.

CONCLUSIONS

Flemish preschoolers had too low vitamin D intakes while most had adequate calcium intakes. Milk (including sweetened, fortified/growth milk) was the main food source of calcium intake and the second important source of vitamin D intake after butter and margarine. Calcium intake was positively associated with parental education, while vitamin D intake was not.

Children and adolescents with severe mental illness need vitamin D supplementation regardless of disease or treatment

BACKGROUND

To protect against osteoporosis, keeping the vitamin D blood level (25[OH]D; VDBL) above 30 ng/mL is recommended. It is established that regular intake of vitamin D, calcium intake, and physical exercise contribute to maximizing bone mineral mass during childhood and adolescence. Recent articles suggest that patients with schizophrenia treated with antipsychotics have low VDBL and may have a higher risk of hip fractures in their later years than the general population.

OBJECTIVES

To evaluate whether adolescent psychiatric inpatient VDBL is lower than the 30-ng/mL optimal threshold and to document low-VDBL risk factors.

METHOD

We determined the VDBL of all consecutive inpatients from three adolescents units in 2009 (N = 136). Univariate analyses explored the influence on VDBL of (1) well-documented risk factors (e.g., age, gender, ethnic origin, body mass index, or season) and (2) suspected risk factors (e.g., disease type or antipsychotic treatment).

RESULTS

All but six patients had a VDBL <30 ng/mL (mean [ ± SD]: 15.9 [ ± 8.4] ng/mL). VDBL was significantly lower for all patients during the first quarter of the year compared to the other three (all p < 0.01). VDBL was also lower for blacks/North Africans 12.8 (±7.0) than for Caucasians/Europeans 17.2 (±8.5): t = 2.62, p = 0.009. We found no differences between patients regarding disease category (K = 3.75, p = 0.154) or antipsychotic treatment (t = 0.127, df = 124, p = 0.89).

CONCLUSION

VDBL in an adolescent population with severe mental illness is lower than current recommendations of optimal level for bone health regardless of treatment or disease type. Because adolescence is a period of bone construction and could represent a critical window of opportunity for maximizing bone mass, especially among patients with severe mental illness, we recommend vitamin D supplementation.

Effect of a general school-based physical activity intervention on bone mineral content and density: a cluster-randomized controlled trial

BACKGROUND

Specific physical loading leads to enhanced bone development during childhood. A general physical activity program mimicking a real-life situation was successful at increasing general physical health in children. Yet, it is not clear whether it can equally increase bone mineral mass. We performed a cluster-randomized controlled trial in children of both gender and different pubertal stages to determine whether a school-based physical activity (PA) program during one school-year influences bone mineral content (BMC) and density (BMD), irrespective of gender.

METHODS

Twenty-eight 1st and 5th grade (6-7 and 11-12 year-old) classes were cluster randomized to an intervention (INT, 16 classes, n=297) and control (CON; 12 classes, n=205) group. The intervention consisted of a multi-component PA intervention including daily physical education with at least 10 min of jumping or strength training exercises of various intensities. Measurements included anthropometry, and BMC and BMD of total body, femoral neck, total hip and lumbar spine using dual-energy X-ray absorptiometry (DXA). PA was assessed by accelerometers and Tanner stages by questionnaires. Analyses were performed by a regression model adjusted for gender, baseline height and weight, baseline PA, post-intervention pubertal stage, baseline BMC, and cluster.

RESULTS

275 (72%) of 380 children who initially agreed to have DXA measurements had also post-intervention DXA and PA data. Mean age of prepubertal and pubertal children at baseline was 8.7±2.1 and 11.1±0.6 years, respectively. Compared to CON, children in INT showed statistically significant increases in BMC of total body, femoral neck, and lumbar spine by 5.5%, 5.4% and 4.7% (all p<0.05), respectively, and BMD of total body and lumbar spine by 8.4% and 7.3% (both p<0.01), respectively. There was no gender *group, but a pubertal stage *group interaction consistently favoring prepubertal children.

CONCLUSION

A general school-based PA intervention can increase bone health in elementary school children of both genders, particularly before puberty.

Bone health and the female athlete triad in adolescent athletes

Peak bone mass (PBM) is a negative predictor of osteoporosis and lifelong fracture risk. Because osteoporosis is such a prevalent disease with life-threatening consequences, it is important to try to maximize PBM. Adolescence is a critical period for bone acquisition. This article discusses some of the differences in male and female skeletal development and modifiable factors that enhance bone accrual in this age group, particularly in athletes. Hormonal influences, effects of physical activity, and nutritional contributions are included, with a focus on the adolescent athlete. Emphasis is placed on the importance of appropriate energy availability in this age group. We also review prevention and treatment strategies for the female athlete triad (ie, the inter-relationship of decreased energy availability, menstrual irregularity, and low bone density) in adolescents and athletic women. Recommendations for maximizing bone density in both male and female adolescents are discussed.