High bone density in young Hutterite children

Fat mass is positively associated with bone mass acquisition in children with small or normal lean mass: A three-year follow-up study

The independent impact of fat mass (FM) on bone health is difficult to assess, as FM is correlated with lean soft tissue mass (LSTM). In a previous cross-sectional study, FM was suggested to help promote high bone mass acquisition in adolescents with small LSTM. The present prospective cohort study investigated the effects of FM on bone in pubertal children after stratification by height-normalized index of LSTM (LSTMI). The source population was all 5th grade children enrolled in either one of the two public elementary schools in Hamamatsu, Japan. Of these, 545 children who participated in both baseline (at age 11) and follow-up (at age 14) surveys were included in the present analysis. Body composition and whole body areal bone mineral density (aBMD) were measured using dual-energy X-ray absorptiometry. From baseline to follow-up, significant (P<0.05) differences were observed in changes in aBMD among tertiles of change in FM in both sexes after adjusting for confounding factors including LSTMI. After stratification by tertiles of sex-specific LSTMI, adjusted means of changes in aBMD according to tertiles of change in FM within the lowest and second lowest tertiles of LSTMI in both sexes showed a significant increase from the lower tertiles to the highest tertile of change in FM. In the highest tertile of LSTMI, changes in FM showed no significant association with changes in aBMD. These findings suggest that adipose tissue might help promote high bone mass acquisition in pubertal children with small or normal LSTMI.

Prevalence and predictors of low serum 25-hydroxyvitamin D levels in rural Canadian children

Objectives

Studies in Canada have reported varying prevalences of low serum 25-hydroxyvitamin D (25(OH)D) levels, but none have been conducted in rural paediatric populations. The purpose of this study was to determine the prevalence and predictors of low vitamin D levels in rural communities.

Methods

We conducted a cross-sectional study of children aged 3 to 15 living in Canadian Hutterite communities. Serum 25(OH)D levels were measured between October 2008 and April 2009 using a chemiluminescence assay. Predictors of vitamin D levels were evaluated using multivariable linear regression. A multilevel model was used to evaluate the impact of individual, household and colony factors on the variation in vitamin D levels.

Results

Serum 25(OH)D levels were available on 743 children/adolescents. The median was 62.0 nmol/L (interquartile range 51.0, 74.0). Levels lower than 50 nmol/L and 75 nmol/L were found in 152 (20.5%) and 565 (76%) children, respectively. Adolescents were at highest risk for levels <75 nmol/L (odds ratio 3.38, 95% confidence interval 2.00, 5.80). Age and latitude were negatively correlated with serum 25(OH)D level. In the multilevel model, most of the variation in levels was associated with individual children.

Conclusion

Low vitamin D levels are a significant problem in rural Hutterite communities in Canada. Adolescents were at greatest risk for low levels and represent an important target group for supplementation. Variation in serum 25(OH)D levels was explained mostly at the individual level. Additional studies are needed to explore factors associated with individuals (e.g., genetics) leading to lower 25(OH)D levels.

Fat mass is positively associated with bone mass in relatively thin adolescents: data from the Kitakata Kids Health Study

Epidemiologic studies have found that higher body weight is associated with better bone health. Body weight consists of both fat mass (FM) and lean soft tissue mass (LSTM). Previous studies have examined the effects of FM levels during childhood on bone health, with conflicting results. In the present study, we investigated the independent contributions of FM to bone mass in Japanese adolescents. Subjects were 235 adolescents aged 15-18 years old in August 2010 and in August 2013 from the Kitakata Kids Health Study in Japan. We obtained cross-sectional data on body composition as well as bone mineral density (BMD). Body composition and BMD were measured using a dual-energy X-ray absorptiometry scanner. We found moderate and positive relationships between FM index and LSTM index (males, r=0.69; females, r=0.44). To verify a potentially additive effect of FM on the variance of bone variables beyond LSTM, we assessed the association between FM index and bone variables after stratification by tertiles of the LSTM index. In the lowest tertile of the LSTM index, FM index was significantly (P<0.05) associated with both femoral neck BMD (males, β=0.48; females, β=0.33) and whole body BMC (males, β=0.41; females, β=0.25). On the other hand, we found no significant associations between FM index and bone variables in other tertiles of the LSTM index. These findings indicate that FM can influence how high bone mass is obtained among relatively thin adolescents, but not among those who are of normal weight or overweight.

Human biology at the interface of paediatrics: measuring bone mineral accretion during childhood

BACKGROUND

Professor Tanner established a paradigm for the study of growth and development that demands precise growth measurements, description of normal variability through development to adulthood, consideration of the effects of tempo and the study of factors that influence growth outcomes. The relatively new field of paediatric bone health assessment fits this paradigm and reflects the collaboration of human biologists and paediatricians in understanding the growth of the human skeleton.

REVIEW

This review describes the reasons for clinical assessment of bone density in children, the technological developments in bone health assessment in children, the development of reference curves and the effects of growth, body composition, pubertal timing, genetics and lifestyle on bone health outcomes.

Longitudinal effects of fat and lean mass on bone accrual in infants

There are conflicting reports on the influence of lean and fat mass on bone accrual during childhood. No infant's studies have been reported that describe the influence of changes in body composition with changes in bone accrual during the first year of life. The objective of this research was to test the hypothesis that greater gains in lean mass will have a positive effect on bone mineral content (BMC) accrual, while greater gains in fat mass will have a negative effect on BMC accrual in infants. Longitudinal data from 3 previous infant studies were used. Linear mixed models, adjusting for age, sex, dietary calcium, and length were used to investigate longitudinal and cross-sectional associations between total body BMC and lean and fat mass in the individual studies and in a combined analysis. In both individual and combined analyses, we found that lean and fat mass were positively associated with whole body BMC accrual (all, P<0.001). The cross-sectional association of BMC and dietary calcium was negative in one study (P<0.05). No differences in BMC change between sexes were observed in three studies. Our results showed positive cross-sectional and longitudinal associations between total body BMC and lean mass in infants. In contradiction to our hypothesis for fat mass, we found a positive cross-sectional and longitudinal association between total body BMC and fat mass in infants.

Cross-sectional versus longitudinal associations of lean and fat mass with pQCT bone outcomes in children

CONTEXT

Cross-sectional associations for lean mass (LM) and fat mass (FM) with bone may not reflect longitudinal associations.

OBJECTIVE

Cross-sectional and longitudinal associations of LM and FM with radial bone measurements in children were compared.

DESIGN AND PARTICIPANTS

We conducted a longitudinal study on 370 (232 females) children, 8-18 yr of age.

MAIN OUTCOME MEASURES

LM and FM were measured by dual-energy absorptiometry. Peripheral quantitative computed tomography at the 4% radius (4R) and 20% radius (20R) measured bone mineral content (BMC), volumetric bone mineral density (vBMD), area, and strength [polar stress strain index (pSSI)].

RESULTS

Males at 20R had negative FM cross-sectional and longitudinal associations with cortical area and BMC and pSSI (P < 0.02); negative cross-sectional association with total area (P < 0.001); and negative longitudinal association with cortical thickness (P < 0.001). Females at 20R had FM cross-sectional association with total area, cortical BMC, and pSSI and longitudinal associations with cortical BMC and area, vBMD, and pSSI that went from positive to negative with age and, in some cases, varied with menarche. Both sexes at 4R had a negative FM cross-sectional association with BMC and area (P < 0.001) but negative longitudinal association with vBMD (P < 0.05). LM associations with bone outcomes were generally positive, except for negative longitudinal associations with cortical BMC and vBMD in young females (P < 0.01). LM associations were greater magnitude than FM associations and often depended on age.

CONCLUSIONS

For males and older females, cross-sectional associations indicated a reduced bone size with higher FM, whereas longitudinal associations showed a decrease in cortical area without changes in bone size. LM was positively associated with BMC and area.

Rates of bone loss in young adult males

Osteoporosis-related fractures occur more frequently in women compared with men, but mortality is greater in men compared with women. Peak bone mass is a significant predictor of osteoporosis and fracture risk; therefore, it is important to optimize peak bone mass during young adulthood. Several recent longitudinal studies, which are summarized in this article, have investigated bone changes among young men. Cortical bone loss does not appear to be significant until individuals reach their mid-30s and is associated with decreased sex hormone concentrations. Significant trabecular bone loss in young men aged in their 20s has been reported and is associated with reduced lean mass and activity levels, especially among former athletes. Whether changes in activity levels among nonathletes lead to bone loss among young men requires further investigation.