Increased fat mass is associated with increased bone size but reduced volumetric density in pre pubertal children

Abstract

Recent studies have shown that obesity is associated with an increased risk of fracture in both adults and children. It has been suggested that, despite greater bone size, obese individuals may have reduced true volumetric density; however this is difficult to assess using two dimensional techniques such as DXA. We evaluated the relationship between fat mass, and bone size and density, in a population cohort of children in whom DXA and pQCT measurements had been acquired. We recruited 530 children at 6 years old from the Southampton Women's Survey. The children underwent measurement of bone mass at the whole body, lumbar spine and hip, together with body composition, by DXA (Hologic Discovery, Hologic Inc., Bedford, MA, USA). In addition 132 of these children underwent pQCT measurements at the tibia (Stratec XCT2000, Stratec Biomedical Systems, Birkenfeld, Germany). Significant positive associations were observed between total fat mass and both bone area (BA) and bone mineral content (BMC) at the whole body minus head, lumbar spine and hip sites (all p<0.0001). When true volumetric density was assessed using pQCT data from the tibia, fat mass (adjusted for lean mass) was negatively associated with both trabecular and cortical density (β=-14.6 mg/mm(3) per sd, p=0.003; β=-7.7 mg/mm(3) per sd, p=0.02 respectively). These results suggest that fat mass is negatively associated with volumetric bone density at 6 years old, independent of lean mass, despite positive associations with bone size.

Quantitative Computed Tomography and Computed Tomography in Children

“…In a cross-sectional cohort (n=172) of 6-year olds in the United Kingdom, Cole et al [18] evaluated tibia trabecular (4% site), cortical vBMD (38% site), and geometric measures, and total fat and lean mass assessed by DXA.…”

Bone mineralization, geometry and strength in pigs growing from 56 to 115 day of life as affected by body fatness

“…Content of the first two components, especially fat, can influence bone size, mineral content and density in adolescents (Janicka et al, 2007;Farr et al, 2010;Cole et al, 2012;Mosca et al, 2014) and adults (Reid et al, 1992;Kirchengast et al, 2001;Hsu et al, 2006;Dytfeld et al, 2011). The results of recent works (Wetzsteon et al, 2008;Aguirre et al, 2014) indicated also that the proportion between fat : lean mass in the body has an important meaning.…”

“…Similarly, Hsu et al (2006) showed an inverse relationship between fat mass and bone density. Cole et al (2012) suggested that fat mass is negatively associated with volumetric bone density in children (independently from lean mass) despite of positive associations with bone size. Similarly, Bredella et al (2011) demonstrated that adipose tissue was inversely associated with bone mineral density, in contrast to muscle content in the organism that positively influenced this bone parameter.…”

Assessing Early Growth and Adiposity: Report from an EarlyNutrition Academy Workshop

“…Around 90% of bone mass is built up during childhood and adolescence, and the impact of these first 2 decades of life on bone health and risk for osteoporosis is well accepted. There is increasing interest to use pQCT for bone assessment in children and adolescents [60]. This technique can be applied to measure the meta- and diaphysis of long bones (radius, tibia or femur) and only requires a low radiation dose [61,62].…”