Endocrinology Unit, Pediatric University Department, Bambino Gesù Children's Hospital, Rome, Italy.
Diabetes and Growth Disorders Unit, Dipartimento Pediatrico Universitario Ospedaliero Bambino Gesù Children's Hospital, Tor Vergata University, Rome, Italy.
Front Endocrinol (Lausanne). 2020 Apr 24;11:200. doi: 10.3389/fendo.2020.00200. eCollection 2020.
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.
儿童时期的超重可能会影响骨骼发育，最终导致骨骼脆弱。之前的报告显示，肥胖儿童四肢骨折的发生率增加，这支持了这种担忧。另一方面，也有证据表明，肥胖儿童的骨矿物质含量高于正常体重的同龄人。脂肪细胞和成骨细胞都来源于多能间充质干细胞（MSCs），肥胖会促使 MSCs 向脂肪细胞分化，而不是向成骨细胞分化。此外，骨髓微环境中的脂肪细胞会释放大量促炎和免疫调节分子，上调破骨细胞的形成和激活，从而导致骨骼脆弱。另一方面，身体脂肪代表一种机械负荷，有利于骨骼积累。在这种情况下，骨骼质量和结构是由炎症和机械刺激的平衡决定的。饮食、体育活动和青春期的激素环境在这种平衡中起着关键作用。在这篇综述中，我们将探讨肥胖儿童和青少年的骨骼是否与正常体重的同龄人相比不健康的问题，并讨论导致骨骼质量和结构差异的机制。我们预计，到目前为止，许多偏见和混杂因素影响了已进行的临床研究，使我们无法得出可靠的结论。样本量、缺乏适当的对照、研究设计的异质性是现有报告的主要缺点。由于肥胖儿童的身体尺寸较大，双能 X 线吸收法可能会高估这些个体的骨密度。磁共振成像、外周定量 CT（pQCT）扫描和高分辨率 pQCT 是准确估计肥胖儿童骨矿物质含量的有前途的技术。此外，肥胖儿童和青少年在成年早期发生骨质疏松症的风险尚无纵向研究。最后，我们将讨论新兴的饮食问题（即多不饱和脂肪酸和多酚对骨骼健康可能有益），因为健康饮食（即地中海饮食）和平衡摄入某些与体力活动相关的营养物质仍然是实现年轻人获得足够骨量的基石，无论其肥胖程度如何。
