(P37-12-26) Body Composition Is Independently Associated With Skeletal Health in 14-Year-Old Adolescents

Objectives: The study aims to explore whether adiposity, nutrition, fitness and low-grade systemic inflammation biomarker affect total bone mineral density in 14 -year- old adolescents.

Methods: Adolescents (n=190) were enrolled in the Beginnings follow-up study at age 14y. Body composition  (FMI, FFMI and BMD) was assessed using DXA. Race-neutral BMD Z-scores were calculated using the LMS method, based on age- and sex-references. Following an overnight fast (≥8 h) CRP (mg/dL) levels were measured (MSD MULTI-SPOT Assay System Vascular Injury Panel 2 (human) Kits, USA). The VO_{2 peak} was determined by indirect calorimetry. Diet quality was assessed using the Healthy Eating Index (HEI-2020), and dietary calcium (mg/d) was derived from 3 food records analyzed with the NDSR software (version 2024). Pubertal status was estimated by self-assessment using the Sexual Maturity Rating (SMR). The study was approved by the IRB of the University of Arkansas for Medical Sciences. Statistical analyses were performed using R (version 4.4.2), and included GLM adjusted for SMR, FMI, FFMI, fitness, HEI, and calcium intake.

Results: A total of 99 females (52%) and 91 males (48%) ( age range =13.4-14.9 years) were enrolled. FMI was negatively associated with BMD (β= -0.008, p=0.02), whereas FFMI was positively associated with BMD (β= 0.035, p< 0.001), independent of SMR, cardiorespiratory fitness test, HEI, and calcium intake. CRP was not associated with BMD (p=0.98). Adolescents were categorized into low BMD Z scores for age (≤ -1.0, N=60) or normal BMD Z scores for age ( >-1.0, N=126). Adolescents with low BMD Z scores had lower FFMI (13.84 ± 1.80 kg/m².  vs. 15.91 ± 2.24 kg/m²., respectively, p< 0.001), and calcium intake (836.65±378.33 mg vs. 1038.94±469.57mg, respectively, p=0.05) compared with those with normal BMD Z scores.

Conclusions: BMD was primarily associated with body composition rather than low-grade systemic inflammation. Adiposity was inversely associated with BMD. Adolescents with lower calcium intake were more likely to present low BMD for age. Therefore, body composition and calcium intake are important factors associated with bone mineralization during adolescence.

Funding Sources: This study was supported by the United States Department of Agriculture (USDA)/Agricultural Research Service (ARS) Project/ /Award Number: 6026-10700-001-000D.