Adult Bone Mass Research Articles

High dose dietary vitamin D3 increases bone mass and strength in mice

Vitamin D plays a critical role in skeletal homeostasis. Vitamin D supplementation is used worldwide to maintain optimal bone health, but the most appropriate level of supplementation remains controversial. This study aimed to determine the effects of varying doses of dietary vitamin D3 on the mechanical properties and morphology of growing bone.Eight-week-old female mice were supplied with one of 3 diets, each containing a different dose of vitamin D3: 1000IU/kg (control), 8000IU/kg or 20,000IU/kg. Mice had ad libitum access to the specialty diet for 4weeks before they were culled and their tibiae collected for further analysis. The collected tibia underwent three-point bending and reference-point indentation from which their mechanical properties were determined, and cortical and trabecular morphology determined by micro computed tomography.Dietary supplementation with 20,000IU/kg vitamin D3 resulted in greater ductility (~200%) and toughness (~150%) compared to the 1000IU/kg control. The 20,000IU/kg diet was also associated with significantly greater trabecular bone volume fraction and trabecular number. The 8000IU/kg diet had no significant effect on trabecular bone mass.We conclude that vitamin D3 supplementation of 20,000IU/kg during early adulthood leads to tougher bone that is more ductile and less brittle than that of mice supplied with standard levels of dietary vitamin D3 (1000IU/kg) or 8000IU/kg. This suggests that dietary vitamin D3 supplementation may increase bone health by improving bone material strength and supports the use of vitamin D3 supplementation, during adolescence, for achieving a higher peak bone mass in adulthood and thereby preventing osteoporosis.

Association between sleep apnea and low bone mass in adults: a systematic review and meta-analysis.

This study aimed to synthesize existing evidence on the potential association between sleep apnea and low bone mass in adults. Electronic searches of five databases were performed. The inclusion criteria consisted of studies in humans that assessed potential associations between sleep apnea and bone metabolic diseases in an adult population. For diagnosis of sleep apnea overnight polysomnography, home polygraphy, or validated records from healthcare databases were considered. Reduced bone density, osteoporosis, serum/urinary levels for markers of bone formation and resorption, or risk of fractures caused without history of trauma were considered indicators of low bone mass. A random-effects model meta-analysis was applied when possible. Of the 963 relevant references, 12 studies met our inclusion criteria and were assessed to be of medium to low bias. Nine out of 12 studies reported an association between sleep apnea and low bone mass (increased bone resorption markers, reduced bone density, and higher risk of osteoporosis). Two studies did not report a significant association, whereas one study reported an increase of bone density in sleep apnea patients compared to non-sleep apnea patients. Meta-analysis of 2 studies (n=112,258 patients) showed that sleep apnea was a significant risk factor for osteoporosis (odds ratio (OR), 1.92; 95%CI, 1.24 to 2.97; I2=66%); females only had an OR of 2.56 (95% CI, 1.96 to 3.34; I2=0%) while the OR in males was 2.03 (95% CI, 1.24 to 3.35; I2=38%). An association between sleep apnea and low bone mass in adults is plausible, but supporting evidence has a risk of bias and is inconsistent.

Sports Practice and Bone Mass in Prepubertal Adolescents and Young Adults: A Cross-sectional Analysis

AIM To compare bone mass and body composition variables between adolescents engaged in high-impact sports and adults who were sedentary during early life. METHOD A cross-sectional study with 155 participants (64 adolescents and 91 adults) aged between 11 and 50 years old. Among the adults, history of sports was evaluated during face-to-face interviews, and information regarding the adolescents' training routines was provided by their coaches. Body composition was evaluated using Dual Energy X-Ray Absorptiometry which provided data about bone mineral density (BMD), bone mineral content (BMC), fat mass (FM), and free fat mass (FFM). RESULTS Adults who engaged in sports practice during early life had higher values of BMC (ES-r = 0.063), FFM (ES-r = 0.391), and lower values of FM (ES-r = 0.396) than sedentary adults. Higher values of BMC (ES-r = 0.063) and BMD in lower limbs (ES-r = 0.091) were observed in active adolescents. Adolescents engaged in sports and adults who were sedentary in early life presented similar values in all bone variables, FM, and FFM. CONCLUSIONS Sports involvement in early life is related to higher bone mass in adulthood. Adolescents engaged in sports presented similar bone mass to adults who had been sedentary in early life.

Depressive symptoms, body composition and bone mass in young adults: a prospective cohort study.

An association between depression and obesity is well recognised, but longitudinal studies of depressive symptoms in adolescents as a predictor of body composition are lacking. We examined depressive symptoms at age 14, 17 and 20 years as predictors of lean, fat and bone mass at age 20 years in a birth cohort. In 1161 participants (569 females) in the Western Australia Pregnancy Cohort (Raine) Study, depressive symptoms were assessed using the Beck Depression Inventory for Youth at age 14 and 17 years, and the Depression, Anxiety and Stress Scale 21 at age 20 years. Participants were further classified into two trajectories using latent class analysis: no/transient and persistent/recurrent depression. At age 20 years, lean body mass (LBM), fat body mass (FBM) and total body bone mass were measured by dual-energy X-ray absorptiometry. In females, accounting for age and lifestyle factors, depression scores at age 14 and 20 years were positively associated with body weight, body mass index (BMI), FBM and % FBM (r=0.110-0.184, P<0.05) but negatively correlated with % LBM (r=-0.120, P<0.05) at age 20 years. Females in the persistent/recurrent depression trajectory (n=99) had significantly higher body weight (+5.1 kg), BMI (+1.8 kg m-2), FBM (+3.9 kg) and % FBM (+2.2%) and significantly lower % LBM (-2.2%) at age 20 years than those with no/transient depression (n=470; all P<0.05). In males, depression scores at age 17 and 20 years were negatively associated with LBM but not weight or BMI, and depression trajectory was not a predictor of body composition at age 20 years. Depression scores and trajectories did not predict bone mass in either males or females. Depressive symptoms and persistent/recurrent depression in adolescence are predictors of greater adiposity at age 20 years in females, but not males, but do not predict bone mass in either gender.

Prevalence and associated factors of low bone mass in adults with systemic lupus erythematosus.

Background Systemic lupus erythematosus (SLE) patients are often treated with glucocorticoids, which place them at risk of bone loss. Objectives The objectives of this article are to determine: (1) the prevalence of low bone mineral density (BMD) and factors associated with low BMD and (2) the prevalence of symptomatic fragility fractures in inception patients of the Toronto Lupus Cohort (TLC). Methods Prospectively collected data from the TLC (1996-2015) of inception patients' first BMD were analyzed. For pre-menopausal women/males <50 years, BMD 'below expected range for age' was defined by Z-score ≤ -2.0 SD. For post-menopausal women/males age 50 or older, osteoporosis was defined by T-score ≤ -2.5 SD and low bone mass by T-score between -1.0 and -2.5 SD. Patients' BMDs were defined as abnormal if Z-score ≤ -2.0 or T-score < -1.0 SD, and the remainder as normal. Descriptive analysis and logistic regression were employed. Results Of 1807 patients, 286 are inception patients with BMD results (mean age 37.9 ± 13.7 years); 88.8% are female. The overall prevalence of abnormal BMD is 31.5%. In pre-menopausal women ( n = 173), the prevalence of BMD below expected range is 17.3%. In post-menopausal women ( n = 81), the prevalence of osteoporosis and low BMD are 12.3% and 43.2%, respectively. Age and cumulative dose of glucocorticoids are statistically significantly associated with abnormal BMD in multivariate analysis. Of 769 inception patients from TLC, 11.1% experienced symptomatic fragility fractures (peripheral and vertebral) over the course of their disease. Conclusion The prevalence of low BMD is high in SLE patients, and is associated with older age and higher cumulative glucocorticoid dose.

Role of connexins and pannexins during ontogeny, regeneration, and pathologies of bone.

Electron micrographs revealed the presence of gap junctions in osteoblastic cells over 40 years ago. These intercellular channels formed from connexins are present in bone forming osteoblasts, bone resorbing osteoclasts, and osteocytes (mature osteoblasts embedded in the mineralized bone matrix). More recently, genetic and pharmacologic studies revealed the role of connexins, and in particular Cx43, in the differentiation and function of all bone types. Furthermore, mutations in the gene encoding Cx43 were found to be causally linked to oculodentodigital dysplasia, a condition that results in an abnormal skeleton. Pannexins, molecules with similar structure and single-membrane channel forming potential as connexins when organized as hemichannels, are also expressed in osteoblastic cells. The function of pannexins in bone and cartilage is beginning to be uncovered, but more research is needed to determine the role of pannexins in bone development, adult bone mass and skeletal homeostasis. We describe here the current knowledge on the role of connexins and pannexins on skeletal health and disease.

Changes in Physical Activity and Sedentary Time are Related to a Better Bone Profile in Youth

The benefits of physical activity (PA) in a positive bone health are well known, and sedentary time (ST) has been independently associated with poor bone mass in adults. In children and adolescents, this relationship is unclear. Moreover, studies strongly support that fat accumulation is unfavorable to bone mass. PURPOSE: To explore whether changes in PA time in different intensities and ST are related to a better bone profile in obese/overweight children and adolescents involved in a school-based PA program. METHODS: 53 youth (28 girls, age=10.6±3.5) took part in an 8-month school-based PA intervention programme. PA by accelerometers, bone area (BA), bone mass (BM), bone mineral density (BMD), percentage of body fat (%BF) by DEXA, and vitamin D (VITD) were taken at the baseline and at the end of the intervention. Three Linear Regression models were done with deltas BA, BM and BMD as dependent variables, and deltas VITD, PA time, and ST as predictors, to analyze the longitudinal effect of PA time and ST changes in bone variables changes. Analyses were adjusted for age, sex and delta height. RESULTS: Descriptive statistics showed significant and positive paired differences for height (2.71%), body mass (1.11%), body lean mass (1.43%), bone area (0.41%), bone mass (0.06%), bone mineral density (0.02%), with p<0.001, and moderate physical activity-MPA (7.39%; p=0.011). There was a significative decrease in sedentary time (-39,09%; p=0.002). Delta ST was negative and significantly associated with deltaBM (β=-.526) and deltaBMD (β=-.019), while deltaMPA was positively associated with deltaBM (β=.673), delta BA(β=.584) and deltaBMD (β=-.014). CONCLUSION: Positive changes in MPA and ST after an 8-months PA intervention program provided significant positive changes in BA, BM, and BMD in children and adolescents, highlighting the positive impact of this type of intervention on children and adolescents bone health.

Predicting bone mineral acquisition during puberty: data from a 3-year follow-up study in Hamamatsu, Japan.

Although most adult bone mass is acquired before adolescence, only a few studies have assessed bone turnover markers in children. Thus, the utility of bone markers to evaluate and predict bone mineral accrual in children is unclear. The present study assessed the association between serum bone markers at 11years of age and subsequent changes in bone gain. Information on bone minerals and bone markers at baseline and at the 3-year follow-up were obtained from 121 children who registered as fifth-grade students in 2010, in Hamamatsu, Japan. Whole-body bone mineral content (WBBMC) and whole-body bone mineral density (WBBMD) were measured using dual-energy X-ray absorptiometry. Boys showed significant (P<0.05) positive relationships between intact osteocalcin at baseline and WBBMC at follow-up (β=0.24), between tartrate-resistant acid phosphatase isoenzyme 5b (TRAP5b) and WBBMC (β=0.34), and between TRAP5b and WBBMD (β=0.34), after adjusting for potential confounding factors. In girls, adjusted means of 3-year gain in both WBBMC and WBBMD significantly increased from the lowest to highest quartiles of type 1 collagen cross-linked C-terminal telopeptide. In boys, adjusted means of 3-year gain in both WBBMC and WBBMD significantly increased from the lowest to highest quartiles of TRAP5b. Children with a high concentration of bone turnover markers tended to exhibit substantial accrual of bone minerals. These results suggest that serum levels of circulating biomarkers at age 11 predict subsequent bone mineral accrual.

Pathophysiology and therapeutic options in osteogenesis imperfecta: an update

Pathophysiology and therapeutic options in osteogenesis imperfecta: an update Evelise Brizola,1 Temis M Félix,2 Jay R Shapiro3 1Bone and Osteogenesis Imperfecta Department, Kennedy Krieger Institute, Johns Hopkins School of Medicine, Baltimore, MD, USA; 2Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; 3Osteoporosis and Metabolic Bone Disorders Center, Bethesda, MD, USAAbstract: Osteogenesis imperfecta (OI) is a rare, heritable systemic disorder of bone and connective tissue, which in almost 90% of cases is due to mutations affecting the normal synthesis of type I collagen. In 1979, four OI phenotypes were categorized which where inherited as autosomal dominant characteristics. Individuals with OI present both genetic and phenotypic variabilities. Major characteristics of OI are bone fragility, blue sclerae, dentinogenesis imperfecta, short stature, scoliosis, and joint hyperextensibility. Both autosomal dominant and recessive inheritance are now recognized. Advances in molecular diagnosis have led to a major expansion in our understanding of the genetic basis for different OI phenotypes. To date, sequence variants in 17 genes are described as causative of OI. These genes regulate the synthesis of type I collagen pro-alpha polypeptide chains, proteins involved in type I collagen processing in the endoplasmic reticulum and proteins involved in osteoblast function. These new genetic associations have also led to uncertainty with regard to the current classification of OI phenotypes. Bisphosphonates have been widely used to improve bone mass and decrease fractures in both children and adults with OI. While effective in many but not all children when administered for 2–4 years, bisphosphonates have not proven effective in adults with OI. Studies are limited for treatment of adults with teriparatide and denosumab. Advances have been reported in the surgical management of OI. Although the role of physical therapy in the management of children and adults was previously described, this important treatment modality is significantly underutilized. Keywords: osteogenesis imperfecta, sequence variants, collagen, bisphosphonates, bone, treatment

Characterization of genetically engineered mouse models carrying Col2a1-cre-induced deletions of Lrp5 and/or Lrp6.

Mice carrying Collagen2a1-cre-mediated deletions of Lrp5 and/or Lrp6 were created and characterized. Mice lacking either gene alone were viable and fertile with normal knee morphology. Mice in which both Lrp5 and Lrp6 were conditionally ablated via Collagen2a1-cre-mediated deletion displayed severe defects in skeletal development during embryogenesis. In addition, adult mice carrying Collagen2a1-cre-mediated deletions of Lrp5 and/or Lrp6 displayed low bone mass suggesting that the Collagen2a1-cre transgene was active in cells that subsequently differentiated into osteoblasts. In both embryonic skeletal development and establishment of adult bone mass, Lrp5 and Lrp6 carry out redundant functions.

The National Osteoporosis Foundation's position statement on peak bone mass development and lifestyle factors: a systematic review and implementation recommendations.

Lifestyle choices influence 20–40 % of adult peak bone mass. Therefore, optimization of lifestyle factors known to influence peak bone mass and strength is an important strategy aimed at reducing risk of osteoporosis or low bone mass later in life. The National Osteoporosis Foundation has issued this scientific statement to provide evidence-based guidance and a national implementation strategy for the purpose of helping individuals achieve maximal peak bone mass early in life. In this scientific statement, we (1) report the results of an evidence-based review of the literature since 2000 on factors that influence achieving the full genetic potential for skeletal mass; (2) recommend lifestyle choices that promote maximal bone health throughout the lifespan; (3) outline a research agenda to address current gaps; and (4) identify implementation strategies. We conducted a systematic review of the role of individual nutrients, food patterns, special issues, contraceptives, and physical activity on bone mass and strength development in youth. An evidence grading system was applied to describe the strength of available evidence on these individual modifiable lifestyle factors that may (or may not) influence the development of peak bone mass (Table 1). A summary of the grades for each of these factors is given below. We describe the underpinning biology of these relationships as well as other factors for which a systematic review approach was not possible. Articles published since 2000, all of which followed the report by Heaney et al. [1] published in that year, were considered for this scientific statement. This current review is a systematic update of the previous review conducted by the National Osteoporosis Foundation [1].Lifestyle FactorGrade Macronutrients FatD ProteinC Micronutrients CalciumA Vitamin DB Micronutrients other than calcium and vitamin DD Food Patterns DairyB FiberC Fruits and vegetablesC Detriment of cola and caffeinated beveragesC Infant Nutrition Duration of breastfeedingD Breastfeeding versus formula feedingD Enriched formula feedingD Adolescent Special Issues Detriment of oral contraceptivesD Detriment of DMPA injectionsB Detriment of alcoholD Detriment of smokingC Physical Activity and Exercise Effect on bone mass and densityA Effect on bone structural outcomesB Considering the evidence-based literature review, we recommend lifestyle choices that promote maximal bone health from childhood through young to late adolescence and outline a research agenda to address current gaps in knowledge. The best evidence (grade A) is available for positive effects of calcium intake and physical activity, especially during the late childhood and peripubertal years—a critical period for bone accretion. Good evidence is also available for a role of vitamin D and dairy consumption and a detriment of DMPA injections. However, more rigorous trial data on many other lifestyle choices are needed and this need is outlined in our research agenda. Implementation strategies for lifestyle modifications to promote development of peak bone mass and strength within one’s genetic potential require a multisectored (i.e., family, schools, healthcare systems) approach.

Associations between hypothalamic–pituitary–adrenal axis function and peak bone mass at 20 years of age in a birth cohort

In older adults, high-normal circulating cortisol levels are associated with lower bone mass, but relationships between hypothalamic–pituitary–adrenal axis function and peak bone mass in young adults have not been examined. We studied 411 male and 390 female participants in the Western Australia Pregnancy Cohort (Raine) Study. At 18years of age, participants underwent a Trier Social Stress Test (TSST) with measurement of plasma and salivary cortisol at baseline and at multiple time points after stress. Cortisol responses were classified as anticipatory responder (significant fall in cortisol during the test), reactive responder (significant increase) or non-responder. At 20years, total body bone mineral content (BMC) and density (BMD) were measured by DXA. In males, after adjustment for weight, height (for BMC and bone area only), alcohol and smoking, there was a significant inverse relationship between both plasma and salivary cortisol measured at baseline in the TSST and each of BMC and BMD, such that each additional 10% of salivary cortisol was associated with reductions of 6.9g (95% CI −11.7, −2.2) in BMC, and 1.8mg/cm2 (95% CI −3.3, −0.4) in BMD. Males classified as anticipatory responders in the TSST had 3.2% lower BMC (adjusted mean±SE: 3131±28 vs. 3233±18g, P=0.006) and 2.5% lower BMD (1108±9 vs. 1136±6mg/cm2, P=0.022) than reactive responders. In females, there were no significant relationships between baseline cortisol or TSST responses and BMC or BMD in covariate-adjusted analyses. We conclude that in young males (but not females), higher circulating cortisol at the baseline of the stress test and an anticipatory responder pattern on the TSST are associated with lower total body bone mass.

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

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

Identification of a dietary pattern prospectively associated with bone mass in Australian young adults

Relatively little is known about the relations between dietary patterns and bone health in adolescence, which is a period of substantial bone mass accrual. We derived dietary patterns that were hypothesized to be related to bone health on the basis of their protein, calcium, and potassium contents and investigated their prospective associations with bone mineral density (BMD), bone area, and bone mineral content (BMC) in a cohort of young adults. The study included 1024 young adults born to mothers who were participating in the Western Australian Pregnancy Cohort (Raine) Study. Dietary information was obtained from food-frequency questionnaires at 14 and 17 y of age. Dietary patterns were characterized according to protein, calcium, and potassium intakes with the use of reduced-rank regression. BMD, bone area, and BMC were estimated with the use of a total body dual-energy X-ray absorptiometry scan at 20 y of age. We identified 2 major dietary patterns. The first pattern was positively correlated with intakes of protein, calcium, and potassium and had high factor loadings for low-fat dairy products, whole grains, and vegetables. The second pattern was positively correlated with protein intake but negatively correlated with intakes of calcium and potassium and had high factor loadings for meat, poultry, fish, and eggs. After adjustment for anthropometric, sociodemographic, and lifestyle factors, a higher z score for the first pattern at 14 y of age was positively associated with BMD and BMC at 20 y of age [differences: 8.6 mg/cm(2) (95% CI: 3.0, 14.1 mg/cm(2)) and 21.9 g (95% CI: 6.5, 37.3 g), respectively, per SD increase in z score]. The z score for this same pattern at 17 y of age was not associated with bone outcomes at 20 y of age. The second pattern at 14 or 17 y of age was not associated with BMD, BMC, or bone area. A dietary pattern characterized by high intakes of protein, calcium, and potassium in midadolescence was associated with higher BMD and BMC at 20 y of age. Our results indicate that high consumption of low-fat dairy products, whole grains, and vegetables in adolescence are associated with beneficial effects on bone development.

Polymorphisms of the WNT16 gene are associated with the heel ultrasound parameter in young adults.

Bone mineral content is influenced by genetic factors. We investigated the role of WNT16 in bone properties determined using quantitative ultrasound (QUS) on young adults. Three WNT16 genetic markers (rs2908007, rs2908004, and rs2707466) were found to have a significant association with the broadband ultrasound attenuation (BUA) measurement, suggesting that WNT16 influences bone mass in young adults. The aim of this study was to investigate whether genetic markers on the WNT16 gene are associated with bone mass, as assessed using QUS in a population of healthy young Spanish adults. A cross-sectional study was conducted on 575 individuals (mean age 20.41 ± 2.69). Bone quality was assessed using BUA measurements (dB/MHz) on the right calcaneus. Six single nucleotide polymorphisms (SNPs) (rs2908007, rs2908004, rs3801387, rs3801385, rs2707466, and rs2536184) covering the WNT16 gene were selected as genetic markers and genotyped to test their association with BUA variations. The rs2908007, rs2908004, and rs2707466 SNPs were found to have a significant association with BUA (p = 0.004, p = 0.001, and p = 0.004, respectively). We demonstrate for the first time that WNT16 genetic polymorphisms influence QUS traits in a population of young adults. This finding suggests that WNT16 might be an important genetic factor in determining peak bone mass acquisition.

Preterm Children Born Small for Gestational Age are at Risk for Low Adult Bone Mass.

Cross-sectional studies suggest that premature birth and low birth weight may both be associated with low peak bone mass. We followed bone traits in preterm individuals and controls for 27 years and examined the effects of birth weight relative to gestational age [stratified as small for gestational age (SGA) or appropriate for gestational (AGA)] on adult bone mineral density (BMD). We measured distal forearm BMC (g/cm) and BMD (g/cm(2)) with single-photon absorptiometry (SPA) in 46 preterm children (31 AGA and 15 SGA) at mean age 10.1 years (range 4-16) and in 84 healthy age-matched children. The measurements were repeated 27 years later with the same SPA apparatus but then also with dual energy absorptiometry and peripheral computed tomography (pQCT). Preterm individuals were shorter (p = 0.03) in adulthood than controls. Preterm AGA individuals had similar BMC and BMD height-adjusted Z-scores in adulthood compared to controls. Preterm SGA individuals had lower distal forearm BMC and BMD height-adjusted Z-scores in adulthood than both controls and preterm AGA individuals. Preterm SGA individuals had lower gain from childhood to adulthood in distal forearm BMC height-adjusted Z-scores than controls (p = 0.03). The deficits in preterm SGA individuals in adulthood were also captured by DEXA in height-adjusted femoral neck (FN) BMC Z-score and height-adjusted FN BMD Z-score and by pQCT in tibial cross-sectional area (CSA) Z-score and stress strain index (SSI) Z-score, where all measurements were lower than controls (all p values <0.05). Preterm SGA individuals are at increased risk of reaching low adult bone mass, at least partly due to a deficit in the accrual of bone mineral during growth. In our cohort, we were unable to find a similar risk in preterm AGA individuals.

Low load, high repetition resistance training program increases bone mineral density in untrained adults.

High load, low repetition resistance training increases BMD in untrained adults; however, many older and untrained adults cannot maintain this type of strenuous program. Our goal was to evaluate whether a low load, high repetition resistance training program would increase BMD in untrained adults. Twenty sedentary, but otherwise healthy, adults (6 men and 14 women, age 28-63 yrs) completed a 27-week group exercise program. The participants were randomly assigned to one of two strength groups: one group completed full body, low load, high repetition weight training classes (S-WEIGHT), while the other group completed core focused fusion classes (S-CORE). Both groups also completed indoor cycling classes for cardiovascular conditioning. After a 3-week familiarization period, all participants completed a 12-week block of 5 fitness classes per week (3 cycling + 2 strength) and concluded with another 12-week block of 6 classes per week (3 cycling + 3 strength). We completed iDXA scans at baseline (week 3) and final (week 28). Compared to baseline, BMD significantly increased for S-WEIGHT in the arms (+4%, P<0.001), legs (+8%, P<0.01), pelvis (+6%, P<0.01) and lumbar spine (+4%, P<0.05), whereas BMD did not significantly change for S-CORE at any site. These results suggest that a low load, high repetition resistance training program may be an effective method to improve bone mass in adults.

Adverse bone health among children and adolescents growing up with HIV

Adverse bone health is one of the important non-communicable conditions during the course of life-long HIV treatment. Adolescence is the critical period of bone mineral acquisition for attaining adult peak bone mass. With traditional and HIV-related risk factors, adolescents growing with HIV have a greater chance of having impaired bone mineral density (BMD). Prevalence of low BMD has been reported in 16–32% of HIV-infected adolescents from middle-income countries. The deep interaction between the immune and skeletal systems, called the immunoskeletal interface, is proposed as one of the underlying mechanisms of adverse bone health in HIV-infected individuals. Dual-energy X-ray absorptiometry (DXA) is a standard tool to assess BMD among HIV-infected adolescents. Non-invasive imaging techniques such as quantitative computed tomography (QCT) and quantitative magnetic resonance imaging (QMRI) provide more information on true volumetric density and bone microarchitecture. To date, there are no paediatric recommendations on the treatment and prevention of adverse bone health. Having a healthy lifestyle, routine weight-bearing exercises and adequate dietary intake are the standard approaches to optimise bone health. There are several ongoing randomised clinical trials using pharmacological treatment options, for example vitamin D, calcium and alendronate to improve bone health among this population.

Early Trabecular Development in Human Vertebrae: Overproduction, Constructive Regression, and Refinement.

Early bone development may have a significant impact upon bone health in adulthood. Bone mineral density (BMD) and bone mass are important determinants of adult bone strength. However, several studies have shown that BMD and bone mass decrease after birth. If early development is important for strength, why does this reduction occur? To investigate this, more data characterizing gestational, infant, and childhood bone development are needed in order to compare with adults. The aim of this study is to document early vertebral trabecular bone development, a key fragility fracture site, and infer whether this period is important for adult bone mass and structure. A series of 120 vertebrae aged between 6 months gestation and 2.5 years were visualized using microcomputed tomography. Spherical volumes of interest were defined, thresholded, and measured using 3D bone analysis software (BoneJ, Quant3D). The findings showed that gestation was characterized by increasing bone volume fraction whilst infancy was defined by significant bone loss (≈2/3rds) and the appearance of a highly anisotropic trabecular structure with a predominantly inferior–superior direction. Childhood development progressed via selective thickening of some trabeculae and the loss of others; maintaining bone volume whilst creating a more anisotropic structure. Overall, the pattern of vertebral development is one of gestational overproduction followed by infant “sculpting” of bone tissue during the first year of life (perhaps in order to regulate mineral homeostasis or to adapt to loading environment) and then subsequent refinement during early childhood. Comparison of early bone developmental data in this study with adult bone volume values taken from the literature shows that the loss in bone mass that occurs during the first year of life is never fully recovered. Early development could therefore be important for developing bone strength, but through structural changes in trabecular microarchitecture rather than bone mass.

The Effect of a Whey Protein Supplement on Bone Mass in Older Caucasian Adults.

It has been assumed that the increase in urine calcium (Ca) that accompanies an increase in dietary protein was due to increased bone resorption. However, studies using stable Ca isotopes have found that dietary protein increases Ca absorption without increasing bone resorption. The objective of the study was to investigate the impact of a moderately high protein diet on bone mineral density (BMD). This was a randomized, double-blind, placebo-controlled trial of protein supplementation daily for 18 months. The study was conducted at two institutional research centers. Two hundred eight older women and men with a body mass index between 19 and 32 kg/m(2) and a self-reported protein intake between 0.6 and 1.0 g/kg participated in the study. Subjects were asked to incorporate either a 45-g whey protein or isocaloric maltodextrin supplement into their usual diet for 18 months. BMD by dual-energy x-ray absorptiometry, body composition, and markers of skeletal and mineral metabolism were measured at baseline and at 9 and 18 months. There were no significant differences between groups for changes in L-spine BMD (primary outcome) or the other skeletal sites of interest. Truncal lean mass was significantly higher in the protein group at 18 months (P = .048). C-terminal telopeptide (P = .0414), IGF-1 (P = .0054), and urinary urea (P < .001) were also higher in the protein group at the end of the study period. There was no difference in estimated glomerular filtration rate at 18 months. Our data suggest that protein supplementation above the recommended dietary allowance (0.8 g/kg) may preserve fat-free mass without adversely affecting skeletal health or renal function in healthy older adults.