Bone Characteristics and Their Determinants in Adolescents and Young Adults with Early-Onset Severe Obesity

Bone mineral density and muscle mass associated with healthy eating index in postmenopausal women; results from RaNCD cohort study

BACKGROUND

The Healthy Eating Index 2015 (HEI-2015) is a tool for checking the quality of diet. This index is used to examine how well people's dietary behavior fits certain criteria for achieving a healthy diet in Dietary Guidelines for Americans 2015-2020. We look at the possible association between the HEI-2015 and bone mineral density (BMD) and muscle strength in postmenopausal women.

METHODS

This research included 1012 postmenopausal women from the recruitment phase of the Ravansar Noncommunicable Diseases (RaNCD) cohort study in Kermanshah-Iran. A standardized and repeatable food-frequency questionnaire (FFQ) that contains 118 items was used to quantify dietary consumption. Anthropometric indices measured via Bio-Impedance Analyzer BIA (Inbody 770, Inbody Co, Seoul, Korea).

RESULT

The mean age of postmenopausal women was (56.41 ± 5.31) years. Participants in the highest quartile had a more daily energy intake compared to the lowest quartile (2329.89 ± 837.59), (P < 0.001). Women in the upper quartiles had greater Skeletal Muscle Mass (SMM) than those in the lower quartiles (21.61 ± 2.80 vs 20.52 ± 3.13; p = 0.0002). The linear model didn't show a significant relationship between HEI score and greater BMD (β = 0.0014, P = 0.169).

CONCLUSION

A diet of high quality followed by a high HEL-2015 score was shown to be strongly connected to increased BMD and muscle mass in Kurdish postmenopausal women.

Obesity and Bone: A Complex Relationship

There is a large literature on the relationship between obesity and bone. What we can conclude from this review is that the increase in body weight causes an increase in BMD, both for a mechanical effect and for the greater amount of estrogens present in the adipose tissue. Nevertheless, despite an apparent strengthening of the bone witnessed by the increased BMD, the risk of fracture is higher. The greater risk of fracture in the obese subject is due to various factors, which are carefully analyzed by the Authors. These factors can be divided into metabolic factors and increased risk of falls. Fractures have an atypical distribution in the obese, with a lower incidence of typical osteoporotic fractures, such as those of hip, spine and wrist, and an increase in fractures of the ankle, upper leg, and humerus. In children, the distribution is different, but it is not the same in obese and normal-weight children. Specifically, the fractures of the lower limb are much more frequent in obese children. Sarcopenic obesity plays an important role. The authors also review the available literature regarding the effects of high-fat diet, weight loss and bariatric surgery.

Modification of bone mineral density, bone geometry and volumetric BMD in young women with obesity

BACKGROUND

Most obese women with low-trauma fractures present normal areal bone mineral density (aBMD), suggesting that other bone parameters are more determinant for fracture risk in these patients.

OBJECTIVES

(i) Determine the effects of obesity in young women on areal bone mineral density (aBMD), bone geometry, strength, and volumetric BMD determined by advanced DXA-based methods; (ii) model the profiles of bone parameters for each population with age; and (iii) determine the factors related to body composition (i.e. lean tissue mass and fat mass) potentially implicated in the "bone adaptation" in the femoral region.

SUBJECTS AND METHODS

Two hundred and twenty adolescent and young women from 18 to 35 years old were enrolled in this study: 128 patients with obesity and 92 age-matched (±6 months) normal-weight controls. aBMD was determined with DXA, whereas hip geometry and strength parameters were assessed by hip structural analysis (HSA) and volumetric BMD by 3D-SHAPER® software.

RESULTS

Compared with controls, subjects with obesity presented significantly higher aBMD at all bone sites, but the difference was greater at hip compared with lumbar spine or radius. Bone size estimates (i.e. cortical thickness), as well as strength estimates (i.e. cross-sectional area) were higher at all femoral subregions including femoral neck, intertrochanteric region and femoral shaft in young women with obesity. In whole proximal femur and all femoral compartments, vBMD was also higher in subjects with obesity, but the difference between groups was greater for cortical vBMD compared with trabecular vBMD. When hip bone parameters were modelled for each group from individual values, maximal values were reached between 20 and 26 years in both groups but, whatever the age, subjects with obesity presented higher values than controls. In both groups, lean body mass (LBM) was the parameter most positively associated with the greatest number of bone parameters studied.

CONCLUSION

Our study confirmed that young women with obesity presented higher aBMD, better hip geometry and greater strength compared with normal-weight controls. Additionally, cortical and trabecular compartments measured by 3D-SHAPER® were favourably and concomitantly modified. However, it remains to be demonstrated whether the evaluation of these new parameters would provide better prediction of fracture risk in this population than aBMD.

Changes in bone mass associated with obesity and weight loss in humans: Applicability of animal models

The implications of obesity and weight loss for human bone health are not well understood. Although the bone changes associated with weight loss are similar in humans and rodents, that is not the case for obesity. In humans, obesity is generally associated with increased bone mass, an outcome which is exacerbated by advanced age and menopause. In rodents, by contrast, bone mass decreases in proportion to severity and duration of obesity, and is influenced by sex, age and mechanical load. Despite these discrepancies, rodents are frequently used to model the situation in humans. In this review, we summarise the existing knowledge of the effects of obesity and weight loss on bone mass in humans and rodents, focusing on the translatability of findings from animal models. We then describe how animal models should be used to broaden the understanding of the relationship between obesity, weight loss, and skeletal health in humans. Specifically, we highlight the aspects of study design that should be considered to optimise translatability of the rodent models of obesity and weight loss. Notably, the sex, age, and nutritional status of the animals should ideally match those of interest in humans. With these caveats in mind, and depending on the research question asked, our review underscores that animal models can provide valuable information for obesity and weight-management research.

Healthy eating index-2015 and bone mineral density among adult Iranian women

This is the first study to examine the potential association of adherence to the healthy eating index-2015 (HEI-2015) and bone health. Findings suggest that better diet quality (i.e., a higher HEI-2015 score) is significantly associated with a small but clinically important increase in bone mineral density among adult Iranian women.

PURPOSE

The HEI-2015 is a multidimensional measure of diet quality used to assess how well people's dietary behaviors align with key recommendations of the 2015-2020 Dietary Guidelines for Americans for achieving a healthy dietary pattern. We examined the potential association of the HEI-2015 and bone mineral density (BMD) among adult Iranian women, hypothesizing that a higher HEI-2015 score is associated with greater BMD.

METHODS

Four-hundred sixteen participants (mean age 48.0 years; 64.7% premenopausal) participated in this cross-sectional study. Lumbar spine and femoral neck BMDs were measured via dual-energy X-ray absorptiometry. Dietary intakes were assessed using a valid and reliable food frequency questionnaire. The HEI-2015 score was calculated based on dietary intakes of 13 components emphasized or minimized in the HEI-2015. The higher the HEI-2015 score, the better the diet quality.

RESULTS

After adjusting for potential covariates in the multiple linear regression analysis, higher HEI-2015 scores were associated with greater lumbar spine and femoral neck BMDs (lumbar spine: standardized beta-coefficient [β] = 0.292; femoral neck: β = 0.192; both P < 0.001). Similar significant associations were found among premenopausal (lumbar spine: β = 0.337; femoral neck: β = 0.262; both P < 0.001) and postmenopausal women (lumbar spine: β = 0.198; femoral neck: β = 0.287; both P < 0.050). Overall, every 10-unit increase in the HEI-2015 score was associated with a 0.03 g/cm² higher multivariable-adjusted BMD at both lumbar spine and femoral neck (both P < 0.001).

CONCLUSION

Findings suggest that better diet quality, as indicated by a higher HEI-2015 score, is significantly associated with a small but clinically important increase in BMD among adult Iranian women.

The Impact of Smoking on Bone Metabolism, Bone Mineral Density and Vertebral Fractures in Postmenopausal Women

BACKGROUND

Smoking is recognized among the risk factors for osteoporosis, but only few studies have comprehensively explored its influence on bone metabolism and strength. We aimed to evaluate smoking effects on calcium-phosphate metabolism, bone mineral density (BMD) and fracture risk in postmenopausal women.

METHODS

Our sample included 1067 postmenopausal women who arrived to our osteoporosis outpatient clinic. Anamnestic data, smoking habits (categorized as never, former, and current; and by smoking intensity and duration), biochemical parameters, lumbar/femoral BMD, and presence of vertebral fractures were recorded. In a subsample of 357 women, the changes in BMD after a 2-yr follow-up period were also assessed.

RESULTS

Current smokers had shorter reproductive age, lower body mass index, and higher prevalence of heavy alcohol consumption than former/never smokers. They also had lower PTH values and weaker linear association between serum vitamin D and parathyroid hormone (current β = -0.11[SE = 0.004]; former β = -0.14[SE = 0.01]; never β = -0.20[SE = 0.003]; p < 0.01 for all). Baseline BMD did not reflect differences based on smoking habits, duration or intensity. However, after 2 years, only current smokers significantly worsened in femural BMD. After adjustment for confounders, the chance of having sustained vertebral fractures at the first evaluation increased by 74% (95% confidence interval:1.07-2.83) in current compared with never smokers, especially among heavy smokers.

CONCLUSIONS

Smoking may negatively affect bone by inhibiting vitamin D-parathyroid hormone axis, reducing estrogen exposure, promoting risky health behaviors, and accelerating bone loss, especially at the femur. No significant differences were observed in these outcomes among former smokers, suggesting that quitting smoking has beneficial effects on bone health.

Adiposity is not beneficial to bone mineral density in 0-5 year old Chinese children: The Jiangsu bone health study

OBJECTIVE

Data on obesity in relation to bone mineral density(BMD) in infants and preschool children were sparse in China. The objective of this study was to examine the associations between body mass index (BMI) and BMD.

SUBJECTS AND METHODS

This was a large population-based multicenter study in which the representative children aged 0-5 years were recruited from 13 Children's Health Care Centers by a stratified cluster random-sampling method in Jiangsu Province, China. BMD was measured by using quantitative ultrasound. The association of BMD with BMI and obesity were evaluated using multiple linear regression and logistic regression analysis taking into account the effects of confounders. The relations between age, weight, height, BMI and BMD were analyzed by using Pearson's correlation and further tested using partial correlation in the additive model.

RESULTS

A total of 5,289 children (2786 boys and 2503 girls) were recruited. The BMD was positively linear relation with age, length/height, and was inversely linear relation with BMI (r=0.711, P<0.001; r=0.727, P<0.001; r=-0.318, P<0.001, respectively). The BMD gradually increased when the weight was in the range within 21.2kg, but started to gain slowlyand even decreased when the weight was over 21.2kg. After adjusting for confounders, compared with control group, children with obesityhad higher odds of low BMD (OR 95%CI: 2.73 (1.57, 4.76), P<0.001), the speed of sound (SOS)value in children with obesity was lower 47.45 (β=-47.45, 95%CI=-85.07, -9.83, P=0.013).

CONCLUSIONS

Adiposity was not advantageous for bone mineral density in 0-5-year-old Chinese children.

Associations between body mass index, body composition and bone density in young adults: findings from a southern Brazilian cohort

BACKGROUND

This study aimed to evaluate the association of body composition components and obesity with bone density.

METHODS

Prospective study with data on 2968 members of the 1993 Pelotas Birth Cohort from follow-ups at 18 and 22 years of age. Areal bone mineral density (aBMD, g/cm²) was evaluated for whole body, lumbar spine, and femoral neck at 22 years using dual-energy X-ray absorptiometry. Simple and multiple linear regression, stratified by sex, were used to assess the effect of BMI, fat mass (FMI) and lean mass index (LMI), evaluated at 18 and 22 years, and obesity trajectories classified by FMI and categorized as "never", "only at 18 years", "only at 22 years" or "always" on aBMD.

RESULTS

Among men, the largest coefficients were observed for BMI, followed by lean mass and fat mass. Compared to fat mass, lean mass presented the largest coefficients for all sites, with the strongest associations observed for the femoral neck (β: 0.035 g/cm²; 95% CI: 0.031; 0.039 for both follow-ups), while the largest effect for FMI was observed for whole-body aBMD at 18 years (β: 0.019 g/cm²; 95% CI: 0.014; 0.024). Among women, the strongest associations were observed for LMI. The largest coefficients for LMI and FMI were observed for femoral neck at age 18, presented β: 0.030 g/cm², 95% CI: 0.026, 0.034 for LMI and β: 0.012 g/cm²; 95% CI: 0.009; 0.015) for FMI. Men who were "always obese" according to FMI had smallest aBMD for spine (β: -0.014; 95%CI: - 0.029; - 0.001). Women who were obese "only at 18 years" had smallest aBMD for the whole-body (β: -0.013; 95%CI: - 0.023; - 0.002), whereas those who were obese "only at 22 years" had larger whole-body and femoral neck aBMD (β: 0.013; 95%CI: 0.009; 0.017 and β: 0.027; 95%CI: 0.016; 0.038, respectively) and those "always obese" for whole-body aBMD (β: 0.005; 95%CI: 0.001; 0.011) compared to the reference category.

CONCLUSIONS

The indexes were positively associated with aBMD in this sample. Fat mass had smaller positive influence on these outcomes than lean mass, suggesting the most important body composition component for bone density is the lean mass.

Testicular Function and Bone in Young Men with Severe Childhood-Onset Obesity

BACKGROUND

Previous studies suggest increased risk for hypoandrogenism and fractures in men with obesity. We aimed to describe the effects of severe childhood-onset obesity on the cross talk between metabolic state, testes, and skeleton at late puberty.

METHODS

A cohort of adolescent and young adult males with severe childhood-onset obesity (n = 21, mean age 18.5 years) and an age-matched control group were assessed for testicular hormones and X-ray absorptiometry-derived bone mass.

RESULTS

Current median body mass indexes for the obese and control subjects were 37.4 and 22.9. Severe early-onset obesity manifested with lower free testosterone (median [interquartile range] 244 [194-332] vs. 403 [293-463] pmol/L, p = 0.002). Lower insulin-like 3 (1.02 [0.82-1.23] vs. 1.22 [1.01-1.46] ng/mL, p = 0.045) and lower ratio of testosterone to luteinizing hormone (2.81 [1.96-3.98] vs. 4.10 [3.03-5.83] nmol/IU, p = 0.008) suggested disrupted Leydig cell function. The degree of current obesity inversely correlated with free testosterone (τ = -0.516, p = 0.003), which in turn correlated positively with bone area at all measurement sites in males with childhood-onset obesity.

CONCLUSIONS

Severe childhood-onset obesity is associated with impaired Leydig cell function in young men and lower free testosterone may contribute to impaired skeletal characteristics.

Obesity and bone metabolism

The interaction between obesity and bone metabolism is complex. The effects of fat on the skeleton are mediated by both mechanical and biochemical factors. Though obesity is characterized by higher bone mineral density, studies conducted on bone microarchitecture have produced conflicting results. The majority of studies indicate that obesity has a positive effect on skeletal strength, even though most likely the effects are site-dependent and, in fact, obese individuals might be at risk of certain types of fractures. Mechanical loading and higher lean mass are associated with improved outcomes, whereas systemic inflammation, observed especially with abdominal obesity, may exert negative effects. Weight loss interventions likely lead to bone loss over time. Pharmacological treatment options seem to be safe in terms of skeletal health; however, the skeletal effects of bariatric surgery are dependent on the type of surgical procedure. Malabsorptive procedures are associated with higher short-term adverse effects on bone health. In this narrative review, we discuss the effects of obesity and weight loss interventions on skeletal health.

Metabolic milieu associates with impaired skeletal characteristics in obesity

High leptin concentration, low-grade inflammation, and insulin resistance often coexist in obese subjects; this adverse metabolic milieu may be the main culprit for increased fracture risk and impaired bone quality seen in patients with type 2 diabetes. We examined the associations of leptin, hs (high sensitivity)- CRP and insulin resistance with bone turnover markers (BTMs) and bone characteristics in 55 young obese adults (median BMI 40 kg/m²) and 65 non-obese controls. Mean age of the subjects was 19.5 ± 2.5 years (mean ± SD). Concentrations of leptin, adiponectin, hs-CRP, MMP-8 and TIMP-1, fasting plasma glucose and insulin (to calculate HOMA), BTMs (BAP, P1NP, CTX-1, and TRAC5b) were measured. Bone characteristics were determined with pQCT at radius and tibia, and with DXA for central sites. Leptin, hs-CRP and HOMA correlated inversely with BTMs: the partial coefficients were 1.5–1.9 fold higher in males than in females. After adjusting for age, BMI, and other endocrine factors, leptin displayed an independent effect in males on radial bone mass (p = 0.019), tibial trabecular density (p = 0.025) and total hip BMD (p = 0.043), with lower densities in males with high leptin. In females, the model adjusting for age, BMI, and other endocrine factors, revealed that hs-CRP had independent effects on radial bone mass (p = 0.034) and lumbar spine BMD (p = 0.016), women with high hs-CRP having lower values. Partial correlations of adiponectin and TIMP-1 with bone characteristics were discrepant; MMP-8 showed no associations. In conclusion, in young obese adults and their controls, leptin, hs-CRP and HOMA associate inversely with BTMs and bone characteristics. Leptin appears to be the key independent effector in males, whereas hs-CRP displayed a predominant role in females.

Peripheral quantitative computed tomography (pQCT) for the assessment of bone strength in most of bone affecting conditions in developmental age: a review

Peripheral quantitative computed tomography provides an automatical scan analysis of trabecular and cortical bone compartments, calculating not only their bone mineral density (BMD), but also bone geometrical parameters, such as marrow and cortical Cross-Sectional Area (CSA), Cortical Thickness (CoTh), both periosteal and endosteal circumference, as well as biomechanical parameters like Cross-Sectional Moment of Inertia (CSMI), a measure of bending, polar moment of inertia, indicating bone strength in torsion, and Strength Strain Index (SSI). Also CSA of muscle and fat can be extracted. Muscles, which are thought to stimulate bones to adapt their geometry and mineral content, are determinant to preserve or increase bone strength; thus, pQCT provides an evaluation of the functional 'muscle-bone unit', defined as BMC/muscle CSA ratio. This functional approach to bone densitometry can establish if bone strength is normally adapted to the muscle force, and if muscle force is adequate for body size, providing more detailed insights to targeted strategies for the prevention and treatment of bone fragility. The present paper offers an extensive review of technical features of pQCT and its possible clinical application in the diagnostic of bone status as well as in the monitoring of the skeleton's health follow-up.