Body composition, oxidative stress and bone strength parameters in patients with obesity: a cross sectional observational study

Introduction Obesity, with its plethora of complications, nowadays causes more deaths of malnutrition. The bone at least was thought to be protected, as this condition is associated with higher BMD and thicke structure, but emerging evidence reporting an increased fracture risk suggests that body composition and other factors may play a detrimental role (1). Indeed, the bone is a dynamic tissue whose resistance is not only influenced by BMD (Bone Mineral Density), but also by geometry, measured through Dual X-ray Absorptiometry (DXA) derived Hip Structural Analysis (HSA). Obesity is a condition characterized by an impaired redox state due to an imbalance between fat produced radicals and antioxidant activity, potentially affecting bone tissue. We herein aimed at analyzing the relationship between oxidative stress indices and body composition with bone density and geometry in subjects with obesity. Methods 42 patients (F 90%) with a mean BMI of 39±8 kg/m 2 and a mean age of 42±12 years underwent a DXA scan for the evaluation of body composition parameters, BMD and HSA. Oxidative stress indices were measured on peripheral blood through commercially available kits. Results Confirming previous reports, we observed a positive correlation between BMI (Body Mass Index) and hip BMD (R.445, p.004), and between BMI and HSA strength parameters FS (Femoral Shaft) CSA (Cross Sectional Area), CSMI (Cross Sectional Moment of Inertia), Z (Section Modulus) (R.337, p.051; R.428, p.012 and R.370, p.031, respectively). Upon correction for age, BMI and gender, an inverse correlation between total fat mass and HSA parameters, in particular NN (narrow neck) CSMI, FS CSA, CSMI and Z (R-.292, p.045; R-.503, p.004; R -.525, p.002; R -.488, p.005, respectively) were observed. Finally, we report an age-, BMI-, and gender-adjusted direct correlation between the antioxidant glutathione peroxidase levels and NN CSA (R.478, p.008), and no correlation with BMD observed. Conclusions Body composition and reduced antioxidant capacity seem to play a diversified role on factors contributing to the risk of fracture in patients with obesity. Further studies are warranted to investigate the mechanisms underlying our findings. Meanwhile, it is important to keep in mind that BMD alone may fail to stratify the risk in this population, making the use of additional parameters in clinical practice possibly useful.