Adipose tissue and volumetric bone mineral density of older Afro-Caribbean men

Abnormal Trabecular and Cortical Bone Microarchitecture in Chronic Hepatitis C Infection and Associations With Select Inflammatory Cytokines

Background

Hepatitis C virus (HCV) infection is associated with reduced bone mineral density (BMD) and increased fracture risk. The structural underpinnings for skeletal fragility with HCV and contributions of inflammatory cytokines remain unknown. We used high-resolution peripheral quantitative computed tomography (HR-pQCT) to compare skeletal parameters by chronic HCV.

Methods

We conducted a cross-sectional study among 58 participants with chronic HCV and 58 participants without HCV. Volumetric BMD and cortical dimensions of the radius and tibia were determined by HR-pQCT; visceral fat area and appendicular lean mass were assessed by whole body dual-energy x-ray absorptiometry; serum levels of tumor necrosis factor α (TNF-α), interleukin 6, and interleukin 18 were measured. Multivariable linear regression was used to estimate group differences in bone measurements and cytokines.

Results

Participants with chronic HCV had lower radius trabecular volumetric BMD (-24.2 mg hydroxyapatite [HA]/cm3) and lower tibia trabecular volumetric BMD (-20.5 mg HA/cm3), cortical area (-20.9 mm2), and cortical thickness (-0.47 mm) than participants without HCV (all P < .05), independent of age, sex, visceral fat area, appendicular lean mass, and smoking. Mean log TNF-α was higher with chronic HCV (+0.1-log pg/mL; P < .001), but no differences in mean log interleukin 6 or interleukin 18 were observed. Higher log TNF-α was associated with lower radius trabecular volumetric BMD (-99.7 mg HA/cm3), lower tibia cortical volumetric BMD (-91.6 mg HA/cm3), and higher tibia cortical porosity (+1.39%) by HR-pQCT (all P < .05).

Conclusions

Patients with chronic HCV had decreased trabecular volumetric BMD and cortical dimensions and higher TNF-α than individuals without infection, suggesting that HCV-associated inflammation might contribute to bone deficits.

Relationship between abdominal fat volume and bone base material pairs from dual-energy spectral computed tomography in young and middle-aged patients with metabolic syndrome

Background

Metabolic syndrome (MetS) has complex effects on bone health, and dual-energy spectral computed tomography (CT) has become increasingly valuable for bone quantification. However, the relationship between bone base material pairs (BMPs) and abdominal fat volume in patients with MetS remains underexplored. This study thus aimed to analyze the relationship between abdominal fat volume and various bone BMPs using dual-energy spectral CT in young and middle-aged patients with MetS.

Methods

Patients with MetS who underwent sleeve gastrectomy at the Center of Obesity and Metabolic Diseases, Beijing Shijitan Hospital, Capital Medical University, from June to November 2021 were retrospectively collected. The abdominal fat measurements and BMPs were acquired using dual-energy spectral CT imaging. These included the volumes of total abdominal fat (TAF), abdominal visceral fat (AVF), and abdominal subcutaneous fat (ASF), as well as bone densities based on hydroxyapatite (water), i.e., HAP (water), and calcium (water), i.e., Ca (water), BMPs. After grouping the patients by sex, we analyzed the differences in clinical and imaging features. The correlation between the clinical and imaging parameters of patients with MetS was evaluated with Pearson correlation coefficients. Age- and sex-adjusted partial correlation analysis between fat volume and bone BMPs was conducted for patients of different sexes. Additionally, multiple linear regression analyses were performed with age, sex, and TAF volume as the independent variables and with Ca (water) and HAP (water) as dependent variables.

Results

A total of 112 young and middle-aged patients with MetS were included in this study, including 85 females and 27 males. Compared to male patients with MetS, the females with MetS exhibited higher lumbar Ca (water) and HAP (water) BMPs, with lower volumes of TAF and AVF and a smaller abdominal circumference (P<0.01). The volumes of TAF, AVF, and ASF were negatively correlated with the average Ca (water) and HAP (water) BMPs in the first to third lumbar vertebrae (L1-L3) (P<0.05). Ca (water) and HAP (water) BMPs decreased with age and increasing TAF volume (P<0.001). The fitted equations for the relationship between bone BMPs with age, sex, and TAF volume were as follows: (I) bone Ca (water) BMP = 76.469 - 0.500 age + 6.762 sex - 0.002 TAF volume; (II) bone HAP (water) BMP =171.704 - 1.138 age + 11.825 sex - 0.004 TAF volume.

Conclusions

In young and middle-aged patients with MetS, the abdominal fat volume was negatively correlated with lumbar bone Ca (water) and HAP (water) BMPs, implying that increased abdominal fat volume may play a crucial role in the pathogenesis of osteopenia among those with MetS. The reduction of bone Ca (water) and HAP (water) with high abdominal fat volume may hold clinical significance for fracture risk in individuals with MetS.

Association between segmental body composition and bone mineral density in US adults: results from the NHANES (2011-2018)

OBJECTIVE

The association between segmental body composition and bone mineral density (BMD) remains uncertain. The primary aim of this cross-sectional investigation was to elucidate the connection between segmental body composition and BMD within the United States adult population.

METHODS

We selected a cohort of 10,096 individuals from the National Health and Nutrition Examination Survey (NHANES) database, with a mean age of 39 years and a mean BMI of 28.5 kg/m². The parameter of segmental body composition was achieved by quantifying body fat and lean mass percentages across various anatomical regions, including the torso, Android, Gynoid, arms and legs. We conducted a weighted multivariate linear regression analysis to investigate the association between segmental body composition and total BMD. Additionally, subgroup analysis was performed based on age and gender.

RESULTS

We found an inverse association between fat proportion in each anatomical region and total BMD, with the arm and leg regions demonstrating the most significant negative correlation. Conversely, a positive correlation was observed between lean mass and BMD across all anatomical regions. These associations remained consistent in subgroup analyses.

CONCLUSION

Our investigation revealed a negative association between adipose levels in various anatomical regions and BMD among Americans aged 20 to 59. Importantly, higher fat proportion in the extremities exerted the most deleterious impact on BMD. Furthermore, an increase in lean mass within each anatomical region was ascertained to confer a positive effect on bone health. Consequently, the evaluation of segmental body composition is well-positioned to predict bone health status.

Association of visceral and subcutaneous fat with bone mineral density in US adults: a cross-sectional study

The relationship between the accumulation of fat in visceral or subcutaneous tissue and bone mineral density (BMD) remains unclear. Our primary objective in this study was to illuminate this relationship by conducting an investigation on a vast scale, encompassing a nationally representative population in the United States. A weighted multiple linear regression model was established to evaluate the relationship between visceral fat, subcutaneous fat, and BMD. Additionally, the exploration of the potential nonlinear relationship was conducted employing the methodology of smooth curve fitting. In order to determine potential inflection points, a two-stage linear regression model was utilized. A total of 10,455 participants between the ages of 20 and 59 were included in this study. Various weighted multiple linear regression models revealed a negative correlation between lumbar BMD and visceral mass index (VMI) and subcutaneous mass index (SMI). However, the association between VMI and lumbar BMD displayed a U-shaped pattern upon employing the smooth curve fitting, and the inflection point of 0.304 kg/m2was determined using a two-stage linear regression model. Our findings indicated a negative association between subcutaneous fat and BMD. A U-shaped relationship was observed between visceral fat and BMD.

Dietary fat intake associated with bone mineral density among visfatin genotype in obese people

Osteoporosis and adipose tissue are closely related with many contradictions. Visfatin is an adipokine that is related to osteoporosis and adiposity. This nutrigenomics study examined the interaction between visfatin genotypes and dietary fat intake, with regard to bone mineral density (BMD) among an obese population. In this cross-sectional study, 336 subjects were enrolled; the mean age was 38·25 (sd 11·69) years and the mean BMI was 31·79 (sd 4·77) kg/m2. Laboratory measurements were lipid profile, insulin and fasting blood sugar. Bone density measurements were assessed by dual-energy X-ray absorptiometry. Dietary data were collected through a 3-d 24-h dietary recall. Genotyping for visfatin gene SNP (rs2110385) was performed by the PCR-restriction fragment length polymorphism method. The frequency of GG, GT and TT genotypes were 33·92 48·51 and 17·54 %, respectively, and 86·6 % of participants were women. The results showed that subjects with TT genotypes had significantly higher lumbar BMD, T score and z score (P<0·0001). After categorisation by percentage of fat intake (30 % of total energy content as a cut-off point), no interaction was found, but when categorised by fat types, we found an interaction between visfatin genotypes and dietary PUFA intake in terms of the hip T score and z score (P=0·043, B= -0·08; P=0·04, B= -0·078, respectively). There was a significant relationship between high PUFA intake and lower energy and protein intake. When participants were categorised by median PUFA intake (22·8 g), it was concluded that subjects with GG genotype who had high PUFA-intake diets had lower hip z scores and T scores, unlike the other genotypes.

Skeletal muscle and pediatric bone development

PURPOSE OF REVIEW

The purpose of this review is to summarize the recent clinical findings surrounding the muscle-bone relationships in children, while considering muscle adiposity, endocrine factors, and lifestyle influences (i.e., diet and exercise) involved in pediatric musculoskeletal development.

RECENT FINDINGS

Positive relationships between cortical bone geometry and muscle mass, size and function have been reported. Prospective studies in particular have helped clarify some of the inconsistent relationships between muscle and cortical bone volumetric density. Muscle fat is associated with impaired glucose handling and muscular functionality, which may in turn have a downstream effect on cortical bone growth during adolescence. Lifestyle factors such as healthful diets and higher impact physical activities can promote optimal skeletal development by improving the muscular phenotype and endocrine profile.

SUMMARY

Muscle and bone are two intricately-related tissue types; however, factors such as sex, maturation, study design, and outcome measures studied can modify this relationship. Further research is warranted to understand the impact of muscle adiposity on cardiometabolic health, muscle function and, subsequently, pediatric musculoskeletal development and fracture risk. Following age-specific diet and physical activity recommendations should be a major focus in obtaining optimal muscle and bone development throughout maturation.

The Relation between Visceral and Subcutaneous Fat to Bone Mass among Egyptian Children and Adolescents

BACKGROUND: The relation between fat distribution and bone mass is still being debated in children and adolescents.AIM: To verify the influence of both visceral and subcutaneous fat on bone mass among Egyptian children and adolescents.SUBJECTS AND METHODS: The study involved 78 (38 boys and 40 girls) individuals from children (42) and adolescents (36), aged 8-17 years. They were divided into 2 age groups: children group (20 boys and 22 girls) aged 8-12 years and adolescent group (18 boys and 18 girls) aged 13-17 years. Anthropometric measurements, visceral and subcutaneous fat (measured by ultrasound), body composition, BMD and BMC (Measured by DXA), were attempted.RESULTS: Among children, significant positive correlations between visceral fat; in males; and subcutaneous fat; in females; with total BMC, BMD and its Z-score were revealed. After exclusion of age effect, the association between visceral fat in females with total BMD and its Z-score and lumbar BMD-Z-score became significant.  For adolescents, no correlation was observed between either visceral or subcutaneous fat with any parameter of bone mass.CONCLUSIONS: Visceral and subcutaneous fat had significant positive association with bone mass in children; males and females respectively. On the contrary such association disappeared during adolescence.

Associations between fat distribution and volumetric bone mineral density in Chinese adults

The aim of this study was to explore the association between fat distribution and volumetric bone mineral density (vBMD) in Chinese Adults. Using a cross-sectional investigation of 867 participants including 521 women and 346 men from China, vBMD and subcutaneous adipose tissue (SCAT) or visceral adipose tissue (VAT) were measured accordingly by quantitative computed tomography. The peak vBMD values of the spine were observed at ages 30-39 years in women and at ages 20-29 years in men. In women, the peak values of VAT and SCAT were observed, respectively, at ages ≥ 70 years and at the age range of 60-69 years. In men, the peak values of VAT and SCAT were observed, respectively, at ages ≥ 70 years and at ages 30-39 years. Using the correlation tests, there was no correlation between SCAT and vBMD in both genders. Most relationships between VAT and BMD were negative (r = -0.204, P < 0.01, in premenopausal women; r = -0.150, P < 0.05, in postmenopausal women; and r = -0.181, P < 0.05, in middle-aged men). After multiple linear regression analysis, no correlations were observed. There appears to be no correlation between fat distribution and vBMD in Chinese adults, and further studies are needed to explore associations between fat distribution and vBMD.

Effects of physical activity and muscle quality on bone development in girls

INTRODUCTION

Poor muscle quality and sedentary behavior are risk factors for metabolic dysfunction in children and adolescents. However, because longitudinal data are scarce, relatively little is known about how changes in muscle quality and physical activity influence bone development.

PURPOSE

In a 2-yr longitudinal study, we examined the effects of physical activity and changes in muscle quality on bone parameters in young girls.

METHODS

The sample included 248 healthy girls age 9-12 yr at baseline. Peripheral quantitative computed tomography was used to measure calf and thigh muscle density, an indicator of skeletal muscle fat content or muscle quality, as well as bone parameters at diaphyseal and metaphyseal sites of the femur and tibia. Physical activity was assessed using a validated questionnaire specific for youth.

RESULTS

After controlling for covariates in multiple regression models, increased calf muscle density was independently associated with greater gains in cortical (β = 0.13, P < 0.01) and trabecular (β = 0.25, P < 0.001) volumetric bone mineral density and the bone strength index (β = 0.25, P < 0.001) of the tibia. Importantly, these relationships were generalized, as similar changes were present at the femur. Associations between physical activity and changes in bone parameters were weaker than those observed for muscle density. Nevertheless, physical activity was significantly (all P < 0.05) associated with greater gains in trabecular volumetric bone mineral density and the bone strength index of the distal femur.

CONCLUSIONS

These findings suggest that poor muscle quality may put girls at risk for suboptimal bone development. Physical activity is associated with more optimal gains in weight-bearing bone density and strength in girls, but to a lesser extent than changes in muscle quality.

Muscle density predicts changes in bone density and strength: a prospective study in girls

OBJECTIVE

We sought to determine whether muscle density, an index of skeletal muscle fat content, was predictive of 2-year changes in weight-bearing bone parameters in young girls.

METHODS

Two-year prospective data from 248 girls, aged 8-13 years at baseline. Peripheral quantitative computed tomography was used to measure changes in bone strength indices (bone strength index [BSI, mg(2)/mm(4)] and strength-strain index [SSIp, mm(3)]) and volumetric bone mineral density [vBMD, mg/cm(3)] at distal metaphyseal and diaphyseal regions of the femur and tibia, as well as calf and thigh muscle density (mg/cm(3)), and muscle cross-sectional area (MCSA, mm(2)), indices of skeletal muscle fat content and muscle force production, respectively.

RESULTS

After controlling for potential confounders, greater gains in femur BSI (44%, P<0.002), total femur vBMD (114%, P<0.04) and femur trabecular vBMD (306%, P<0.002) occurred in girls in the lowest versus the highest groups of baseline thigh muscle density. Greater gains in tibial BSI (25%, P<0.03) and trabecular vBMD (190%, P<0.002) were also observed in the lowest versus the highest baseline calf muscle density groups.

CONCLUSION

Baseline muscle density is a significant predictor of changes in bone density and bone strength in young girls during a period of rapid skeletal development.

Top 10 research questions related to body composition

An understanding of body composition is crucial to understanding human health, disease, and function. Research in body composition has focused on the development of assessment methods, description of normal changes in body composition with growth and development and aging, and the changes that occur in body composition in response to challenges ranging from illness to planned interventions. Each focus is significant, and in a sense, they are interdependent, because technological advances allow more sophisticated questions to be addressed, which in turn drives the development of better methods. Significant advances have been made in each area, although perhaps surprisingly basic questions remain. For example, growth trajectories are often estimated from cross-sectional data, given the resources needed for long-term observational studies, and thus, longitudinal descriptive data are still needed. Along with advances in laboratory methods, development of field methods remains relevant for screening and clinical practice. Despite recognition of wide interindividual differences in intervention response, average outcomes continue to be emphasized. With technological advances, it is now possible to examine genetic along with nongenetic factors that underlie changes in body composition, and these techniques need to be applied in long-term, well-controlled trials. In this article, we review 10 key questions in related areas in which research is needed to continue to advance the field.

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 2 years' 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 2 years 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 2 years 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.

Relationship of body fat and its distribution with bone mineral density in Indian population

Obesity has been associated with increased bone mineral density (BMD). There is evidence of differential effect of regional fat on BMD. Hence, we undertook this study to evaluate the correlation between total body fat and its distribution with BMD in nonobese (mean body mass index: 25.0 ± 4.7 kg/m²) Indian adult volunteers. A total of 2347 participants (men: 39.4% and women: 60.6%) included in this cross-sectional study were divided according to sex and age. Fasting blood samples were drawn for biochemical parameters. Percent total body, truncal, and leg fat and BMD at lumbar spine, femur, and forearm were measured by dual-energy X-ray absorptiometry. The BMD at all sites (radius, femur, and spine) increased from lowest to highest quartiles of percent body fat. Percent truncal fat was positively correlated with BMD at all sites in both sexes, except for femoral neck in men, where it had negative correlation. Percent leg fat was positively related with BMD at all sites in premenopausal women, and spine and radius BMD in postmenopausal women. However, in men, it had negative correlation with femoral neck BMD. On multiple regression analysis, regional fat had positive association with BMD at all sites after adjusting for age, sex, lean mass index, 25-hydroxyvitamin D, and intact parathyroid hormone levels. Leg-to-total body fat ratio was negatively associated with BMD at all sites in men and pre- and postmenopausal women. Percent total body and regional fat have positive association with BMD at all sites in men and women.

Longitudinal relationships between whole body and central adiposity on weight-bearing bone geometry, density, and bone strength: a pQCT study in young girls

Longitudinal relationships between adiposity (total body and central) and bone development were assessed in young girls. Total body and android fat masses were positively associated with bone strength and density parameters of the femur and tibia. These results suggest adiposity may have site-specific stimulating effects on the developing bone.

INTRODUCTION

Childhood obesity may impair bone development, but the relationships between adiposity and bone remain unclear. Failure to account for fat pattern may explain the conflicting results.

PURPOSE

Longitudinal associations of total body fat mass (TBFM) and android fat mass (AFM) with 2-year changes in weight-bearing bone parameters were examined in 260 girls aged 8-13 years at baseline. Peripheral quantitative computed tomography was used to measure bone strength index (BSI, square milligrams per quartic millimeter), strength-strain index (SSI, cubic millimeters), and volumetric bone mineral density (vBMD, milligrams per cubic centimeter) at distal metaphyseal and diaphyseal regions of the femur and tibia. TBFM and AFM were assessed by dual-energy x-ray absorptiometry.

RESULTS

Baseline TBFM and AFM were positively associated with the change in femur BSI (r = 0.20, r = 0.17, respectively) and femur trabecular vBMD (r = 0.19, r = 0.19, respectively). Similarly, positive associations were found between TBFM and change in tibia BSI and SSI (r = 0.16, r = 0.15, respectively), and femur total and trabecular vBMD (r = 0.12, r = 0.14, respectively). Analysis of covariance showed that girls in the middle thirds of AFM had significantly lower femur trabecular vBMD and significantly higher tibia cortical vBMD than girls in the highest thirds of AFM. All results were significant at p < 0.05.

CONCLUSIONS

Whereas baseline levels of TBFM and AFM are positive predictors of bone strength and density at the femur and tibia, higher levels of AFM above a certain level may impair cortical vBMD growth at weight-bearing sites. Future studies in obese children will be needed to test this possibility.

Relation of visceral and subcutaneous adipose tissue to bone mineral density in chinese women

The relationship between adipose and bone tissues is still being debated. The purpose of our study was to evaluate whether the distribution and volume of abdomen adipose tissue are correlated to trabecular bone mineral density in the lumbar spine. In this cross-sectional study, 320 Chinese women, being divided into two groups according to age ≥55 years and <55 years, were evaluated with quantitative computed tomography (QCT) of the spine to simultaneously evaluate the average trabecular BMD of L2-L4, VAT, and SAT. Possible covariates of height, weight, age, and comorbidities were considered. In the <55-year-old sample, multiple linear regression analyses indicated that VAT volume was negatively correlated to trabecular BMD (P value = 0.0003) and SAT volume had no correlation to trabecular BMD. In contrast, there was no significant correlation between VAT or SAT and BMD in the ≥55-year-old sample. Our results indicate that high VAT volume is associated with low BMD in Chinese women aged <55 years and SAT has no relation with BMD.

Advances in osteoimmunology: pathophysiologic concepts and treatment opportunities

Osteoimmunology is an emerging research area that deals with the mutual interactions between bone and the immune system. Osteoclasts have long been the center of attention in osteoimmunological research due to their hematopoietic origin and strong activation through cytokines. However, also the osteoclast's opponent - the osteoblast - has recently sought the spotlight, and novel functions of its descendant - the osteocyte - have been unraveled. A considerable number of investigations carried out over the past decade have identified critical proteins with osteoimmune functions including the pro-osteoclastic cytokine receptor activator of NF-ĸB ligand and inhibitors of the pro-osteoblastic Wnt signaling pathway. These discoveries have also led to the development of targeted therapies to counteract not only inflammation-induced bone loss but also postmenopausal osteoporosis and osteoporosis associated with aging.

Body composition and skeletal health: too heavy? Too thin?

The relationship between body composition and skeletal metabolism has received growing recognition. Low body weight is an established risk factor for fracture. The effect of obesity on skeletal health is less well defined. Extensive studies in patients with anorexia nervosa and obesity have illuminated many of the underlying biologic mechanisms by which body composition modulates bone mass. This review examines the relationship between body composition and bone mass through data from recent research studies throughout the weight spectrum ranging from anorexia nervosa to obesity.

Relationship between MRI-measured bone marrow adipose tissue and hip and spine bone mineral density in African-American and Caucasian participants: the CARDIA study

CONTEXT

An increasing number of studies suggest that bone marrow adipose tissue (BMAT) might play a role in the pathogenesis of osteoporosis. Our previous study of Caucasian women demonstrated that there is an inverse relationship between BMAT and whole-body bone mineral density (BMD). It is unknown whether visceral adipose tissue (VAT), sc adipose tissue (SAT), and skeletal muscle had an effect on the relationship between BMAT and BMD.

OBJECTIVE

In the present study we investigated the relationship between pelvic, hip, and lumbar spine BMAT with hip and lumbar spine BMD in the population-based Coronary Artery Risk Development in Young Adults (CARDIA) sample with adjustment for whole-body magnetic resonance imaging (MRI)-measured VAT, SAT, and skeletal muscle.

DESIGN

T1-weighted MRI was acquired for 210 healthy African-American and Caucasian men and women (age 38-52 yr). Hip and lumbar spine BMD were measured by dual-energy x-ray absorptiometry.

RESULTS

Pelvic, hip, and lumbar spine BMAT had negative correlations with hip and lumbar spine BMD (r = -0.399 to -0.550, P < 0.001). The inverse associations between BMAT and BMD remained strong after adjusting for demographics, weight, skeletal muscle, SAT, VAT, total adipose tissue (TAT), menopausal status, lifestyle factors, and inflammatory markers (standardized regression coefficients = -0. 296 to -0.549, P < 0.001). Among body composition measures, skeletal muscle was the strongest correlate of BMD after adjusting for BMAT (standardized regression coefficients = 0.268-0.614, P < 0.05), with little additional contribution from weight, SAT, VAT, or total adipose tissue.

CONCLUSION

In this middle-aged population, a negative relationship existed between MRI-measured BMAT and hip and lumbar spine BMD independent of demographics and body composition. These observations support the growing evidence linking BMAT with low bone density.

Relationship between abdominal fat and bone mineral density in white and African American adults

Several studies have documented relationships between adipose tissue and bone mineral density (BMD); however, the degree to which there are racial differences in this relationship is not known. The purpose of this study was to examine the relationships between abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) and BMD among white and African American adults. The sample included 330 white women, 328 African American women, 307 white men, and 116 African American men 18-74 years of age. Dual-energy X-ray absorptiometry scans were used to measure BMD and computed tomography scans were used to measure abdominal VAT and SAT. Linear regression was used to assess the relationships between abdominal adiposity and BMD and to explore possible sex and race differences in the associations. In the total sample as well as in all sex-by-race groups, VAT and SAT were negatively related to BMD, after adjustment for lean body mass (LBM) and several covariates. The VAT model (including covariates) explained 33.3% of the variance in BMD and the SAT model (including covariates) explained 32.7% of the variance in BMD. Being African American, being male, and having high LBM were all associated with higher BMD. Race and sex interactions were not significant, indicating that the relationships were similar across race and sex groups. In conclusion, BMD was inversely related to abdominal VAT and SAT in white and African American adults after adjustment for LBM.

Skeletal muscle fat content is inversely associated with bone strength in young girls

Childhood obesity is an established risk factor for metabolic disease. The influence of obesity on bone development, however, remains controversial and may depend on the pattern of regional fat deposition. Therefore, we examined the associations of regional fat compartments of the calf and thigh with weight-bearing bone parameters in girls. Data from 444 girls aged 9 to 12 years from the Jump-In: Building Better Bones study were analyzed. Peripheral quantitative computed tomography (pQCT) was used to assess bone parameters at metaphyseal and diaphyseal sites of the femur and tibia along with subcutaneous adipose tissue (SAT, mm(2) ) and muscle density (mg/cm(3) ), an index of skeletal muscle fat content. As expected, SAT was positively correlated with total-body fat mass (r = 0.87-0.89, p < .001), and muscle density was inversely correlated with total-body fat mass (r = -0.24 to -0.28, p < .001). Multiple linear regression analyses with SAT, muscle density, muscle cross-sectional area, bone length, maturity, and ethnicity as independent variables showed significant associations between muscle density and indices of bone strength at metaphyseal (β = 0.13-0.19, p < .001) and diaphyseal (β = 0.06-0.09, p < .01) regions of the femur and tibia. Associations between SAT and indices of bone strength were nonsignificant at all skeletal sites (β = 0.03-0.05, p > .05), except the distal tibia (β = 0.09, p = .03). In conclusion, skeletal muscle fat content of the calf and thigh is inversely associated with weight-bearing bone strength in young girls.