Total Body Bone Area Research Articles

Fetal exposure to bisphenols and phthalates and childhood bone mass: a population-based prospective cohort study.

BackgroundExposure to bisphenols and phthalates might influence bone health. We hypothesized that exposure to bisphenols and phthalates during fetal life has persistent effects on bone development. ObjectivesTo analyze the associations of fetal exposure to bisphenols and phthalates with bone health in school-aged children. MethodsAmong 1,362 mother-child pairs participating in a population-based cohort study, we measured maternal urinary concentrations of bisphenols and phthalates at first, second and third trimester with high performance liquid chromatography electrospray ionization-tandem mass spectrometry. Total body bone mineral density (BMD) and bone area (BA) were measured using dual-energy X-ray absorptiometry (DXA) at 6 and 10 years, and were both used to calculate bone mineral content (BMC) and area-adjusted BMC (aBMC, a measure of volumetric BMD). ResultsMaternal bisphenol concentrations were not associated with childhood bone measures at 6 years. After adjustment for covariates and multiple testing correction, an interquartile range increase in maternal first trimester bisphenol S (BPS) concentrations was associated with lower BMD and aBMC at 10 years (−6.08 (95% confidence interval (CI), −9.97 to −2.19) mg/cm2 and -0.12 (95% CI, −0.20 to −0.04) g). Maternal third trimester low molecular weight (LMW) phthalate concentrations were associated with higher aBMC at 6 years whereas, maternal third trimester di-n-octylphthalate (DNOP) concentrations were associated with lower aBMC at 10 years. However, these associations did not remain statistically significant after multiple testing correction. DiscussionMaternal first trimester BPS concentrations are associated with lower BMD and aBMC in school-aged children. These findings should be considered as hypothesis generating and need further replication and exploration of potential underlying mechanisms.

Examination of protein intakes at 2-years and weight status and body composition at 5-years in the Cork BASELINE Birth Cohort

AbstractDietary protein is critical for normal growth and development through its contribution of essential amino acids. In high-resource settings, protein intakes are generally adequate. Previous studies have suggested that higher protein intakes in infancy and early childhood are associated with higher body mass index in later childhood.This analysis was performed in a subgroup of 2-year-old children (n = 468) with detailed dietary intake data (2-d weighed food record) participating in an extensively-characterised, prospective birth cohort, the Cork BASELINE Birth Cohort Study (n = 2183). Body weight and height were measured at 2- and 5-years, and indices of body composition (fat mass, fat free mass) were obtained at 5 years in a subgroup of 295 children. Total protein intake was estimated at 2-years and the contribution of animal and plant sources to total protein intake was quantified. Children were split into thirds of protein intake (as % total energy, %TE) and anthropometry and body composition at 5 years was compared across groups. The relationship between protein intake (total and animal sources) and BMI-SDS, fat mass index-SDS and fat free mass index-SDS was explored in multivariate linear regression models, adjusted for common confounders (energy intake, gestational age, duration of breastfeeding, birthweight-SDS, maternal education).Mean (SD) daily protein intake was 41.3 (11.2) g/d, representing 16.1 %TE (girls: 16.2 %TE; boys: 15.9 %TE, P = 0.202) and all children met EFSA average requirement and population reference intake thresholds. Meat (25%), cows’ milk (22%), breads (7%), yoghurt (6%), breakfast cereals (6%) and cheese (5%) were key sources of protein intake in toddlers. The majority of dietary protein intake was from animal sources (69%).Girls with high %TE from protein [mean (SD): 19.7 (2.6) %TE] were significantly heavier and taller at 5 years than their counterparts [low: 13.1 (1.4) %TE; medium: 16.0 (0.7) %TE], and had significantly higher fat free mass, fat free mass index and total body bone area (indicative of body size), but not fat mass. When adjusted for confounders in multivariate regression models, no association was observed between total protein intake and BMI-SDS, fat mass index-SDS or fat free mass index-SDS at 5 years.Children with high animal protein intakes (as %TE) had significantly higher fat free mass than their low and medium group counterparts; however, when adjusted for height and other confounders, no association was observed.Protein intakes in early childhood were associated with larger body size, but not BMI or body composition at 5-years.

Associations between serum levels of insulin-like growth factor-I and bone mineral acquisition in pubertal children: a 3-year follow-up study in Hamamatsu, Japan

BackgroundEpidemiological data regarding the association between serum levels of IGF-I and bone mineral acquisition during childhood are scarce. Here, we investigated the association between serum levels of IGF-I and bone status during puberty.MethodsWe analyzed prospective 3-year follow-up data of 254 community-dwelling children who completed both baselines (at age 11.2 years) and follow-up (at age 14.2 years) surveys in Hamamatsu, Japan. Total body (TB) bone area and bone mineral parameters were assessed using dual-energy X-ray absorptiometry.ResultsDuring the 3-year follow-up period, there were significant (P < 0.05) increases in total body less head (TBLH) areal bone mineral density (aBMD), TBLH bone mineral content (BMC), and TB bone area, and a significant decrease in TB bone mineral apparent density (BMAD, volumetric bone mineral density, vBMD). IGF-I levels showed significant positive relationships with TBLH BMC and TBLH aBMD at both baseline and follow-up. TBLH aBMD in boys and TB BMAD in girls at follow-up showed significant increases from the lowest to highest quartiles of baseline IGF-I levels after adjusting for confounding factors. Similarly, changes in TBLH aBMD in boys and TB BMAD in girls during the 3-year follow-up period showed significant increases from the lowest to highest quartiles of baseline IGF-I levels after adjusting for confounding factors.ConclusionsThese results suggest that pubertal children with high levels of serum IGF-I tended to have high bone mineral acquisition later on.

Whole egg consumption and cortical bone in healthy children.

This study examined the relationships between egg consumption and cortical bone in children. The cross-sectional study design included 294 9-13-year-old black and white males and females. Three-day diet records determined daily egg consumption. Peripheral quantitative computed tomography measured radius and tibia cortical bone. Body composition and biomarkers of bone turnover were assessed using dual-energy X-ray absorptiometry and ELISA, respectively. Egg intake was positively correlated with radius and tibia cortical bone mineral content (Ct.BMC), total bone area, cortical area, cortical thickness, periosteal circumference, and polar strength strain index in unadjusted models (r = 0.144-0.224, all P < 0.050). After adjusting for differences in race, sex, maturation, fat-free soft tissue mass (FFST), and protein intakes, tibia relationships were nullified; however, egg intake remained positively correlated with radius Ct.BMC (r = 0.138, P = 0.031). Egg intake positively correlated with total body bone mineral density, BMC, and bone area in the unadjusted models only (r = 0.119-0.224; all P < 0.050). After adjusting for covariates, egg intake was a positive predictor of radius FFST (β = 0.113, P < 0.050) and FFST was a positive predictor of Ct.BMC (β = 0.556, P < 0.050) in path analyses. There was a direct influence of egg on radius Ct.BMC (β = 0.099, P = 0.035), even after adjusting for the mediator, FFST (β = 0.137, P = 0.020). Egg intake was positively correlated with osteocalcin in both the unadjusted (P = 0.005) and adjusted (P = 0.049) models. If the positive influence of eggs on Ct.BMC observed in this study is confirmed through future randomized controlled trials, whole eggs may represent a viable strategy to promote pediatric bone development and prevent fractures.

Bone Mineral Density Is Positively Related to Carotid Intima-Media Thickness: Findings From a Population-Based Study in Adolescents and Premenopausal Women.

ABSTRACTOsteoporosis and cardiovascular disease (CVD) are both common causes of morbidity and mortality. Previous studies, mainly of people older than 60 years, suggest a relationship between these conditions. Our aim was to determine the association between bone characteristics and CVD markers in younger and middle‐aged individuals. Women (n = 3366) and their adolescent offspring (n = 4368) from the UK population‐based cohort study, Avon Longitudinal Study of Parents and Children (ALSPAC), were investigated. We measured total body (TB) and hip bone mineral density (BMD), TB bone area (BA) and bone mineral content (BMC) by dual‐energy X‐ray absorptiometry (DXA), and carotid intima‐media thickness (cIMT) by high‐resolution ultrasound. Arterial distensibility was calculated as the difference between systolic and diastolic arterial diameters. Linear regression determined associations between bone exposures and cIMT (in adolescents) and both cIMT and arterial distensibility (in women), generating partial correlation coefficients. Mean (SD) age of women was 48 (4.2) years, body mass index (BMI) was 26.2 (5.0) kg/m2, and 71% were premenopausal. In confounder‐adjusted analyses (age, height, lean mass, fat mass, menopause, smoking, estrogen replacement, calcium/vitamin D supplementation, and education) TB and hip BMD were both positively associated with cIMT (0.071 [0.030, 0.112], p = 0.001; 0.063 [0.025, 0.101], p = 0.001, respectively). Femoral neck BMD and TB BMD, BMC, and BA were positively associated with arterial distensibility. Mean (SD) age of adolescents was 17 (0.4) years, BMI was 23 (4.1) kg/m2, and 44.5% were male. Total hip and TB measurements were positively associated with cIMT, with similar magnitudes of association to those found in their mothers. In contrast to most published findings, we identified weak positive associations between BMD and cIMT in predominantly premenopausal women and their adolescent offspring. We found greater femoral neck BMD and TB DXA measurements to be associated with reduced arterial stiffness. Rather than a relationship with preclinical atherosclerosis, in these relatively young populations, we speculate our associations between BMD, cIMT, and arterial distensibility may reflect a shared relationship between bone and vascular growth and development. © 2016 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Bone Health Status in Indian Overweight/Obese Children.

This cross-sectional study, to assess bone health in Indian overweight, obese children in comparison with healthy controls was conducted in 245 (126 girls) children and adolescents aged 6-17y in Pune, India. It was found that total body bone mineral content, bone area and bone mineral density adjusted for Tanner stage and weight were significantly lower in obese children as compared to overweight children, which in turn, was significantly lower than normal weight children (p < 0.05). Thus, overweight and obesity is negatively related to bone health in children and adolescents. Interventions need to be planned to increase peak bone mass accrual in overweight and obese children to reduce future risk of fracture and osteoporosis.

Bone status of Indian children and adolescents with type 1 diabetes mellitus

ObjectiveLow bone mineral density has been reported in children and adolescents with type 1 diabetes (T1DM). The aims of this cross-sectional study were to study growth, serum IGF1 concentrations and bone health parameters assessed by Dual Energy X-ray Absorptiometry (DXA). MethodsHeight was measured and converted to Z scores (HAZ). Serum IGF1 concentrations were measured (ELISA) in a subset. Bone mineral content for total body (less head) (TBBMC) and lumbar spine was measured (n=170, 77 boys, 6–16years old) and converted to Z scores using local normative data. ResultMean age was 11.1±3.8years, disease duration was 2.2±2.5years and HbA1C was 10.1±1.8%. Diabetic children were shorter than reference population (HAZ −0.6±1.1); Z scores for height and total body bone area (TBBA) for height were <−2SD in 12% & 6% respectively. Serum IGF1 Z scores were lower amongst group with longer disease duration (−1.58±1.3 vs −2.63±0.7; P=0.037). Disease duration (β=−0.180, P=0.000) and metabolic control (HbA1C; β=−0.096, P=0.042) were negative predictors of HAZ and TBBA for height Z in younger children. Using the Molgaard approach, children with longer disease duration had lower HAZ (−0.31±0.92 vs −1.28±1.11; P=0.000; “short bones”) and TBBA for height Z scores (0.12±1.62 vs −0.53±0.94; P=0.044; “slender bones”). Older children (tanner stages 4 and 5) had lower BMC and BA as compared to reference population possibly due to delayed growth spurt. ConclusionLonger duration of diabetes was associated with shorter and slender but appropriately mineralized bones. Small and slender bones in diabetic children may increase risk of fragility fractures in the future.This article is part of a Special Issue entitled “Bone and diabetes”.

Does fetal smoke exposure affect childhood bone mass? The Generation R Study

We assessed the intrauterine influence of maternal smoking on childhood bone mass by comparing parental prenatal and postnatal smoking habits. We observed higher bone mass in children exposed to maternal smoking, explained by higher body weight. Maternal smoking or related lifestyle factors may affect childhood weight gain rather than skeletal growth. Maternal smoking during pregnancy may adversely affect bone health in later life. By comparing the associations of maternal and paternal smoking and of prenatal and postnatal exposure with childhood bone measures, we aimed to explore whether the suggested association could be explained by fetal programming or reflects confounding by familial factors. In 5565 mothers, fathers and children participating in a population-based prospective cohort study, parental smoking habits during pregnancy and current household smoking habits were assessed by postal questionnaires. Total body bone mineral content (BMC), bone area (BA) and bone mineral density (BMD) were measured by dual-energy X-ray absorptiometry (DXA) at the median age of 6.0 years (IQR 0.37). In confounder-adjusted models, maternal smoking during pregnancy was associated with a higher BMC of 11.6 g (95 % confidence interval (CI) 5.6, 17.5), a larger BA of 9.7 cm(2) (95 % CI 3.0, 16.4), a higher BMD of 6.7 g/cm(2) (95 % CI 2.4, 11.0) and a higher BMC of 5.4 g (95 % CI 1.3, 9.6) adjusted for BA of the child. Current weight turned out to mediate these associations. Among mothers who did not smoke, paternal smoking did not show evident associations with childhood bone measures. Also, household smoking practices during childhood were not associated with childhood bone measures. Our results do not support the hypothesis of fetal smoke exposure affecting childhood bone mass via intrauterine mechanisms. Maternal smoking or related lifestyle factors may affect childhood weight gain rather than skeletal growth.

Conditional disruption of miR17-92 cluster in collagen type I-producing osteoblasts results in reduced periosteal bone formation and bone anabolic response to exercise.

In this study, we evaluated the role of the microRNA (miR)17-92 cluster in osteoblast lineage cells using a Cre-loxP approach in which Cre expression is driven by the entire regulatory region of the type I collagen α2 gene. Conditional knockout (cKO) mice showed a 13-34% reduction in total body bone mineral content and area with little or no change in bone mineral density (BMD) by DXA at 2, 4, and 8 wk in both sexes. Micro-CT analyses of the femur revealed an 8% reduction in length and 25-27% reduction in total volume at the diaphyseal and metaphyseal sites. Neither cortical nor trabecular volumetric BMD was different in the cKO mice. Bone strength (maximum load) was reduced by 10% with no change in bone toughness. Quantitative histomorphometric analyses revealed a 28% reduction in the periosteal bone formation rate and in the mineral apposition rate but with no change in the resorbing surface. Expression levels of periostin, Elk3, Runx2 genes that are targeted by miRs from the cluster were decreased by 25-30% in the bones of cKO mice. To determine the contribution of the miR17-92 cluster to the mechanical strain effect on periosteal bone formation, we subjected cKO and control mice to 2 wk of mechanical loading by four-point bending. We found that the periosteal bone response to mechanical strain was significantly reduced in the cKO mice. We conclude that the miR17-92 cluster expressed in type I collagen-producing cells is a key regulator of periosteal bone formation in mice.

Gender differences in the relationships between lean body mass, fat mass and peak bone mass in young adults

The relationships between fat mass and bone mass in young adults are unclear. In 1,183 young Australians, lean body mass had a strong positive relationship with total body bone mass in both genders. Fat mass was a positive predictor of total body bone mass in females, with weaker association in males. Body weight and lean body mass are established as major determinants of bone mass, but the relationships between fat mass (including visceral fat) and peak bone mass in young adults are unclear. The aim of this study was to evaluate the associations between bone mass in young adults and three body composition measurements: lean body mass, fat mass and trunk-to-limb fat mass ratio (a surrogate measure of visceral fat). Study participants were 574 women and 609 men aged 19-22 years from the Raine study. Body composition, total body bone mineral content (TBBMC), bone area and areal bone mineral density (TBBMD) were measured using DXA. In multivariate linear regression models with height, lean body mass, fat mass and trunk-to-limb fat mass ratio as predictor variables, lean mass was uniquely associated with the largest proportion of variance of TBBMC and TBBMD in males (semi-partial R(2) 0.275 and 0.345, respectively) and TBBMC in females (semi-partial R(2) 0.183). Fat mass was a more important predictor of TBBMC and TBBMD in females (semi-partial R(2) 0.126 and 0.039, respectively) than males (semi-partial R(2) 0.006 and 0.018, respectively). Trunk-to-limb fat mass ratio had a weak, negative association with TBBMC and bone area in both genders (semi-partial R(2) 0.004 to 0.034). Lean body mass has strong positive relationship with total body bone mass in both genders. Fat mass may play a positive role in peak bone mass attainment in women but the association was weaker in men; different fat compartments may have different effects.

Infant and maternal bone status are associated in lactating adolescents when calcium intake is low but not following calcium plus vitamin D supplementation

The aim of the study was to evaluate the influence of calcium plus vitamin D supplementation during adolescent pregnancy on relationships between infant and maternal bone status during lactation. Adolescent mothers (13–19y) with dietary calcium intake ≈600 mg/d, received daily calcium (600 mg) plus vitamin D3 (200 IU) (n=30) or placebo (n=25) from 26 wk gestation until parturition. Infant and maternal DXA scans were done at 5 wk postpartum. Infant measures included total body bone mineral content (BMC), bone area (BA), and bone mineral density (BMD). In mothers, BMD was measured at total body, lumbar spine (L1–L4), total hip and femoral neck. Associations between infant bone measurements and maternal BMD Z scores were evaluated by partial correlation analysis. In the placebo group, infant BMC and BA were negatively associated with maternal total BMD Z score (r = −0.40; P &lt; 0.05 and r = −0.47; P &lt; 0.02, respectively) while infant BMD was positively associated with mothers’ BMD Z scores at all evaluated regions (r ≥ 0.39; P ≤ 0.05). No associations between infant and maternal bone measurements were observed in the supplemented group. Our results suggest that in adolescent pregnancy the calcium demand for neonate bone accumulation is supplied at the expense of maternal bone mass when calcium intake is low.Financial support: CNPq and FAPERJ (Brazil).

Fat mass increase in 7-year-old children: More Bone Area but lower Bone Mineral density

The main aims of this study were, to evaluate what effect a change in fat mass (FM) and lean body mass (LBM) has on bone parameters over 2years' time, in 7-year-old school children and to see what effect fitness had on bone parameters in these children. A repeated-measures design study was conducted where children born in 1999 from six elementary schools in Reykjavik, Iceland were measured twice. All children attending second grade in these six schools were invited to participate. Three hundred twenty-one children were invited, 211 underwent dual-energy X-ray absorptiometry (DXA) scans at the age of seven, and 164 (78%) of the 211 had DXA scans again 2years later. Increase in both FM and LBM was associated with increased total body bone mineral content (BMC) and bone area (BA). An increase in FM was more strongly positively associated with BA while an increase in LBM was more strongly associated with an increase in BMC. An increase in FM was negatively associated with change in bone mineral density (BMD), but an increase in LBM was positively associated with change in BMD. Fitness was positively associated with bone parameters when weight, height and sex were accounted for. The present results suggest that an increase in fat mass over 2years is associated with an increase in BA and BMC, but a decrease in BMD in the whole body. An increase in LBM accrual, on the other hand, is positively associated with all bone parameters in the body. Fitness is associated with both BMC and BMD but not BA.

Insulin-like growth factor-1 cytokines cross-talk in type 1 diabetes mellitus: Relationship to microvascular complications and bone mineral density

ObjectiveThis study was designed to investigate the association between inflammatory cytokines (IL-8, IL-6) and IGF-1 levels in relation to metabolic control, microvascular complications and bone mineral density (BMD) in a cohort of Egyptian adolescents with T1DM. Research design and methodsSixty patients with T1DM (mean age was 14.67±1.53years, mean disease duration was 6.87±1.25years) and 40 controls participated in the study. Thirty-six patients (60%) had poor glycemic control (HbA1C measurements ⩾8%) while the rest (n=24%, 40%) had good glycemic control (HbA1C measurements <8%). Serum IL-6, IL-8, and IGF-1 levels were measured. Whole body DXA scan were assessed. Total body and lumbar spine (L2–L4) bone mineral content (BMC, g) and bone area (BA, cm2) were measured by DXA scan, bone mineral density (BMD, g/cm2) was calculated by BMC/BA. ResultsPatients with T1DM had higher IL-6 and IL-8 levels with lower IGF-1 than healthy controls (P<0.001). Within the T1DM patients those with poor glycemic control had higher IL-6 and IL-8 as well as lower IGF-1 and total BMD than those with good glycemic control (P<0.001 for all). IL-6 and IL-8 were negatively correlated with IGF-1 (P=0.005 and 0.021, respectively). The peripheral neuropathy rate was also greater in T1DM patients with poor glycemic control (P=0.02). Presence of nephropathy or retinopathy was not different (P=0.69 and 0.50, respectively). ConclusionHigh IL-6, IL-8 with low IGF-1 levels are found in adolescents with T1DM. It seems that poor glycemic control exacerbates inflammatory cytokines, increases peripheral neuropathy, and decreases bone mineral density.

Poor bone health in underprivileged Indian girls: An effect of low bone mass accrual during puberty

A socio-economic gradient exists for most reasons of morbidity and mortality including delayed puberty in lower (LSES) as compared to higher (HSES) socio-economic stratum and puberty is an important factor affecting bone status in children and adolescents. Thus, a cross-sectional study was conducted on 195 age-matched pairs of girls (8–17years) from LSES and HSES in Pune City, India to assess the hypothesis that socio-economic factors working through late puberty would have a negative association with bone status of adolescents. Height, weight and Tanner stage were assessed. Total body bone mineral content (TBBMC), total body bone area (TBBA), total body bone mineral density (TBBMD), lean body mass (LBM) and total body fat mass (TBFM) were measured using GE Lunar DPX Pro Pencil Beam DXA (Wisconsin, USA) scanner. Mean TBBMC (1172±434g), TBBA (1351±356cm2), TBBMD (0.846±0.104g/cm2), LBM (21,622±5306g) and TBFM (7746±5194g) in LSES girls were significantly lower than that of HSES girls [TBBMC (1483±525g), TBBA (1533±380cm2), TBBMD (0.942±0.119g/cm2), LBM (24,308±5829g) and TBFM (12,196±7404g)] (p<0.01). There was a significant effect of age and puberty on all bone parameters. The differences in TBBMC, TBBA, LBM and TBFM between the 2 socio-economic strata at Tanner stage I were not significant (p>0.1) whereas there were significant differences in these parameters from Tanner stages II to V (p<0.05). The percentage difference between LSES and HSES girls in TBBMC, TBBA, TBBMD, LBM and TBFM was 3.4%, 0%, 3.7%, 0.2% and 17.3% respectively at Tanner stage I which increased to 19.1%, 9.7%, 10.4%, 8.8% and 31.2% respectively at Tanner stage V. In conclusion, our results suggest that pubertal years may provide a window of opportunity to promote bone health in adolescent girls from the lower socio-economic stratum.

Insights into the programming of bone development from the Avon Longitudinal Study of Parents and Children (ALSPAC)

We examined associations between proxy measures of in utero nutrition and total body bone mineral content (BMC), bone area (BA), and bone mineral density (BMD) assessed at age 9.9 y in the Avon Longitudinal Study of Parents and Children (ALSPAC). There were positive relations between birth weight and BMC, BA, and BMD. These associations were explained by the co-association of birth weight with body size in later childhood. In height- and weight-adjusted analyses, an inverse association was observed between birth weight and BMD at age 9.9 y, which suggests that birth weight had a negative influence on bone mass after relations with bone and body size were taken into account. In analyses of associations between bone mass at age 9 y and background ultraviolet B exposure during the third trimester of pregnancy (a proxy measure for maternal vitamin D status), maternal ultraviolet B exposure was positively related to BMC, BA, and BMD. After adjustment for height, these associations were only partially attenuated, which suggests that maternal ultraviolet B exposure affected skeletal size and mass independently of longitudinal growth, possibly by the increase of periosteal expansion. There was a positive relation between maternal folate intake and BMD of the spine subregion independent of body size. Although a co-association with folate intake in childhood could explain this relation, the maternal methylenetetrahydrofolate reductase (MTHFR) genotype affected spine BMD independently of the child MTHFR genotype, which suggests that maternal folate status has an independent effect on bone development of offspring. Together, these results confirm that there is a relation between bone development in childhood and several proxy measures for nutritional status in utero.

Maternal and paternal relationships with offspring bone mass: response to Harvey et al.

Dear Editor, We thank Harvey et al. for their comment [1] regarding our paper comparing relationships of maternal and paternal smoking during pregnancy with offspring bone measures at age 10 years in the Avon Longitudinal Study of Parents and Children (ALSPAC) [2]. We agree that the associations the authors report of maternal smoking and pre-pregnancy BMI with offspring whole body bone mineral content (BMC) at birth in the Southampton Women’s Survey, without similar paternal effects [1], provide some support for intrauterine influences on fetal bone development. However, we emphasise that in our study we aimed to assess whether any intrauterine effects on bone mineral accrual persist into childhood. The authors refer to differences between maternal and paternal associations in our complete case analysis as potentially representing an intrauterine effect. We point out that in our complete case, as in our multiple imputation analysis, there were similar-sized associations of maternal and paternal smoking with offspring total body BMC, bone area and bone mineral density in confounder-adjusted models; parental differences were apparent only in models for spinal bone outcomes. Furthermore, in both analyses, any associations of maternal smoking with offspring bone measures were positive, and thus in the opposite direction to those found with BMC at birth [1, 3, 4], and completely explained by the child’s height and, in particular, weight. Our findings, therefore, are not consistent with an adverse intrauterine effect of maternal smoking on bone development which persists into later childhood. In our other study referenced by the authors, the positive relationship of maternal BMI with offspring bone mass at age 10 years [5] is consistent with that reported at birth [1]. In our complete case, but not in our multiple imputation analysis, maternal effects were slightly stronger than paternal effects, so an intrauterine influence is plausible. However, detailed analyses suggested that these associations were completely driven by the association of maternal BMI with child’s BMI, rather than direct effects on bone development. Previous studies investigating maternal and paternal–offspring BMI associations have had inconsistent findings [6–9], although similar associations of maternal and paternal BMI with offspring BMI demonstrated in ALSPAC [6] and in the largest study to date [9] give support to our findings from multiple imputation of similarsized parental BMI associations with offspring bone mass. Finally, the authors suggest that maternal smoking status and BMI during/pre-pregnancy will be highly correlated with those post-pregnancy. We would expect that this is also true for fathers, suggesting that effects of parental exposures would be similar unless there was a specific effect of the maternal exposure during the intrauterine period [10]. Furthermore, we do not agree that an association of birth weight with later bone density is proof of an intrauterine effect. Smoking is the strongest environmental determinant of birth weight and strongly related to socioeconomic position (and largely explains the association of socioeconomic position with birth weight [11]); thus, familial socioeconomic position and associated lifestyles would C. Macdonald-Wallis (*) :G. Davey Smith :D. A. Lawlor MRC Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK e-mail: C.Macdonald-Wallis@bristol.ac.uk

Diet containing low n-6/n-3 polyunsaturated fatty acids ratio, provided by canola oil, alters body composition and bone quality in young rats

Adipocytes and osteoblasts were derived from a common progenitor, and canola oil intake may have an adipogenic and osteogenic effect. Thus, our objective was to evaluate the effect on adipocyte, lipid profile, glucose homeostasis, and bone of canola oil as main lipid source on the diet during development. After weaning, rats were divided into two groups (n=10 per group): control (S) and experimental (C) diets containing 7mL/100g soybean or canola oil, respectively. At 60days, body composition, liver and intra-abdominal fat mass, adipocyte morphology, serum analysis, femur and lumbar vertebras density by dual-energy X-ray absorptiometry and computed tomography were determined. Differences were considered significant with P<0.05. C group showed the following: lower liver (-12%) and intra-abdominal fat mass (-19%) area of adipocyte (-60%), cholesterol (-33%), insulin (-22%), lower total body (-9%) and spine (-33%) bone mineral content and bone area (-7 and -24%, respectively), femur mass (-9%), width of the diaphysis (-6%), femur (-10%) and lumbar vertebrae bone mineral density (-9%), and radiodensity of femoral head (-8%). The lower intra-abdominal adiposity could have more beneficial effects in a short term, since it can be associated with a better insulin sensitivity and lipid profile, than the small reduction in femur and lumbar vertebra density. However, it has to be considered the incremental effect of this reduction along the aging process.

Bone mineral accrual from 8 to 30 years of age: An estimation of peak bone mass

Bone area (BA) and bone mineral content (BMC) were measured from childhood to young adulthood at the total body (TB), lumbar spine (LS), total hip (TH), and femoral neck (FN). BA and BMC values were expressed as a percentage of young-adult values to determine if and when values reached a plateau. Data were aligned on biological ages [years from peak height velocity (PHV)] to control for maturity. TB BA increased significantly from -4 to +4 years from PHV, with TB BMC reaching a plateau, on average, 2 years later at +6 years from PHV (equates to 18 and 20 years of age in girls and boys, respectively). LS BA increased significantly from -4 years from PHV to +3 years from PHV, whereas LS BMC increased until +4 from PHV. FN BA increased between -4 and +1 years from PHV, with FN BMC reaching a plateau, on average, 1 year later at +2 years from PHV. In the circumpubertal years (-2 to +2 years from PHV): 39% of the young-adult BMC was accrued at the TB in both males and females; 43% and 46% was accrued in males and females at the LS and TH, respectively; 33% (males and females) was accrued at the FN. In summary, we provide strong evidence that BA plateaus 1 to 2 years earlier than BMC. Depending on the skeletal site, peak bone mass occurs by the end of the second or early in the third decade of life. The data substantiate the importance of the circumpubertal years for accruing bone mineral.

Modifiable factors associated with low bone mineral content in underprivileged premenarchal Indian girls

Low adolescent peak bone mass is associated with bone problems in adulthood. Our aim was to assess underprivileged premenarchal Indian girls for low bone mineral content and to study the influence of anthropometric, lifestyle factors on bone health. Data on anthropometry, diet, lifestyle, total body bone mineral content (TBBMC), bone area, bone mineral density, and biochemical parameters [parathyroid hormone, vitamin D (25OH-D), calcium, and zinc] were assessed in 214 premenarchal girls (8-12 years). Compared with the Indian reference database, 15.6% girls had TBBMC for age Z-scores below -2 and 37.5% had Z-scores between -2 and -1. The TBBMC for total body bone area Z-scores were below -2 for one fifth of girls, indicating undermineralized bones. Mean rate of increase in TBBMC with age and Tanner stage was lower in our study population (11.6% and 20.7%, respectively) than reference database (14.2% and 33.4%, respectively). Low weight, 25OH-D, and intake of protein, calcium, and zinc adversely affected TBBMC (p < 0.05). Many underprivileged premenarchal Indian girls are at risk of achieving low bone mass. Steps to improve underweight, 25OH-D, intakes of protein, calcium, and zinc might improve bone health.

Vitamin D supplementation and bone mass accrual in underprivileged adolescent Indian girls.

Vitamin D deficiency is common among children and adolescents in India, in spite of abundant sunshine. We conducted a pilot; double blind randomised controlled trial to investigate the effect of vitamin D supplementation on bone mineral content in underprivileged adolescent girls, in Pune, India. Fifty post-menarcheal girls aged 14 to 15 years were randomised to receive 300,000 IU (7.5 mg) of ergocalciferol or placebo orally, 4 times/year. All participants received 250 mg elemental calcium (calcium carbonate) daily. Outcome measures included change in serum 25-hydroxyvitamin D, size adjusted bone area and bone mineral content at total body and lumbar spine. Post supplementation, the median serum concentration of 25-hydroxyvitamin D was 75.2 (64.2-85.5) nmol/L in the intervention group and 28.1 (16.7-34.0) nmol/L in the placebo group. Increment in bone outcome measures was not different in the two groups. However, there was a positive effect of intervention in the size adjusted total body bone area (p<0.05), total body bone mineral content (p<0.05) and lumbar spine bone mineral content (p<0.05), and positive trend in lumbar spine bone area (p=0.07) in girls who were within 2 years of menarche. We conclude that vitamin D supplementation did not have a beneficial effect on skeletal mineralization in girls who were more than 2 years post menarcheal. However, there was a significant positive effect of the intervention on size adjusted total body and lumbar spine bone mineral content and a positive trend in lumbar spine bone area, in girls who were <= 2 years of menarche.