The role of trunk region body composition in lumbar spine bone mineral content and density

Abstract

BACKGROUND: The aim of this study was to investigate the differential effects of trunk region body composition-specifically fat mass (FM) and lean mass (LM)-on lumbar spine bone mineral density (BMD) and bone mineral content (BMC), with a focus on variations by gender and menopausal status. MATERIALS AND METHODS: We identified 331 adult patients (69 men, 161 premenopausal women, and 101 postmenopausal women) who underwent dual-energy X-ray absorptiometry (DXA) to simultaneously measure trunk body composition and lumbar spine BMD (L(2)-L(4)). The Pearson correlation coefficient was used to assess the linear relationships between body composition components and lumbar spine BMD and BMC, stratified by gender and menopausal status. Additionally, multiple linear regression analysis with the forward stepwise elimination procedure was applied to find a reasonable subset of predictor variables. RESULT: The highest correlation coefficients between body composition and BMD were seen for men and post- and premenopausal individuals in the following areas: pelvic fat mass (r = 0.325; P < 0.01), chest lean mass (r = 0.260; P < 0.01), and total lean mass (r = 0.312; P < 0.01), respectively. Additionally, total lean mass (r = 0.477; P < 0.01), chest lean mass (r = 0.360; P < 0.01), and total lean mass (r = 0.459; P < 0.01) had the strongest correlation coefficients between body composition and BMC. Forward stepwise regression identified age, chest lean mass, and midriff fat mass as predictors of BMC in postmenopausal women; BMI and total lean mass in premenopausal women; and total lean mass in men. For BMD, chest lean mass (postmenopausal), total lean mass (premenopausal), and BMI (men) were significant predictors. CONCLUSIONS: Fat mass does not affect BMD or BMC, while lean mass, strongly predicts bone health. Trunk body composition showed varying relationships with BMD and BMC, making it challenging to pinpoint how lean mass distribution in the chest and midriff specifically impacts bone health.