The Bones of Children With Obesity

Abstract

Excess adiposity in childhood may affect bone development, ultimately leading to bone frailty. Previous reports showing an increased rate of extremity fractures in children with obesity support this fear. On the other hand, there is also evidence suggesting that bone mineral content is higher in obese children than in normal weight peers. Both adipocytes and osteoblasts derive from multipotent mesenchymal stem cells (MSCs) and obesity drives the differentiation of MSCs toward adipocytes at the expense of osteoblast differentiation. Furthermore, adipocytes in bone marrow microenvironment release a number of pro-inflammatory and immunomodulatory molecules that up-regulate formation and activation of osteoclasts, thus favoring bone frailty. On the other hand, body adiposity represents a mechanical load, which is beneficial for bone accrual. In this frame, bone quality, and structure result from the balance of inflammatory and mechanical stimuli. Diet, physical activity and the hormonal milieu at puberty play a pivotal role on this balance. In this review, we will address the question whether the bone of obese children and adolescents is unhealthy in comparison with normal-weight peers and discuss mechanisms underlying the differences in bone quality and structure. We anticipate that many biases and confounders affect the clinical studies conducted so far and preclude us from achieving robust conclusions. Sample-size, lack of adequate controls, heterogeneity of study designs are the major drawbacks of the existing reports. Due to the increased body size of children with obesity, dual energy absorptiometry might overestimate bone mineral density in these individuals. Magnetic resonance imaging, peripheral quantitative CT (pQCT) scanning and high-resolution pQCT are promising techniques for the accurate estimate of bone mineral content in obese children. Moreover, no longitudinal study on the risk of incident osteoporosis in early adulthood of children and adolescents with obesity is available. Finally, we will address emerging dietary issues (i.e., the likely benefits for the bone health of polyunsaturated fatty acids and polyphenols) since an healthy diet (i.e., the Mediterranean diet) with balanced intake of certain nutrients associated with physical activity remain the cornerstones for achieving an adequate bone accrual in young individuals regardless of their adiposity degree.

Survey of MRI Usefulness for the Clinical Assessment of Bone Microstructure

“…Bone loss occurs early after the initiation of corticosteroid therapy and is correlated to dose and treatment duration [ 29 ]. Fragility fractures have been associated with early mortality and increased morbidity having a significant effect on the quality of life of both patients affected by diabetes [ 30 , 31 , 32 ], anorexia nervosa [ 33 , 34 ], and obesity [ 35 , 36 , 37 ].…”

Predictors of Bone Mineral Density in Adolescents With Excess Weight

“…1 The skeletal system is one of the organic systems with intense development at this stage of the life cycle, period in which the peak bone mass occurs and the magnitude of this process contributes to reduce the risk of fractures in adulthood. 2 Body weight, age and sexual maturation can be considered as the main factors related to bone mass during adolescence. 3 The variation in peak bone mass is explained by numerous factors, such as gender, race, dietary habits and physical activity, hereditary factors, hormonal factors, presence of intercurrent diseases, chronic use of medications and body composition characteristics.4 Adiposity excess, although associated with increased bone size, can have an adverse effect on its quality.…”

“…3 The variation in peak bone mass is explained by numerous factors, such as gender, race, dietary habits and physical activity, hereditary factors, hormonal factors, presence of intercurrent diseases, chronic use of medications and body composition characteristics.4 Adiposity excess, although associated with increased bone size, can have an adverse effect on its quality. 2 Increased body weight interferes with both bone mass acquisition and loss and is directly linked to the risk of being overweight or obese. 4 Adipose and bone tissues are metabolically active organs due to the constant production and release of molecules, cytokines and hormones.…”

“…These molecules modulate via endocrine and paracrine signaling a number of metabolic activities. 2 The pathophysiological role of adipose tissue in bone tissue homeostasis is probably related to the action of these molecules in a homeostatic feedback system, in which adipokines and molecules secreted by osteoblasts and osteoclasts act on the bone-adipose-active axis. Deregulation of secreted factors in adipose tissue is not only linked to overweight and its complications, but also has important effects on bone metabolism.…”

“…5 Obesity is a worrisome condition due to the increasing number of cases in children and adolescents, being a strong predictor of adult obesity 6 and related to the presence of comorbidities in all life cycle stages. 2 The prevalence of overweight and obesity among children and adolescents aged 5 to 19 increased dramatically from only 4% in 1975 to just over 18% in 2016. While just under 1% of children and adolescents aged 5 to 19 were obese in 1975, more than 124 million children and adolescents (6% of girls and 8% of boys) were obese in 2016, which requires immediate public health actions.…”