Associations of Plasma and Fecal Metabolites with Body Mass Index and Body Fat Distribution in Children

Context: Childhood obesity continues to be a critical public health concern with far-reaching implications for well-being. Objective: This study aimed to investigate the association between metabolites in plasma and feces and indicators including body mass index (BMI), BMI for age Z score (BMIZ), and body fat distribution among children aged 6 to 9 years in China. Methods: This cross-sectional study enrolled 424 healthy children, including 186 girls and 238 boys. Dual-energy X-ray absorptiometry was used to determine the body fat content and regional fat distribution. Plasma and fecal metabolites were analyzed using targeted metabolomic technologies. Results: A total of 200 plasma metabolites and 212 fecal metabolites were accurately quantified via ultra-performance liquid chromatography coupled with tandem mass spectrometry. By using orthogonal projections to latent structures discriminant analysis and random forest model, we discovered that 9 plasma metabolites and 11 fecal metabolites were associated with different weight statuses. After adjusting for potential covariates and false discovery rate correction, multiple linear regression analyses revealed that plasma metabolites (fumaric acid, glycine, l-glutamine, methylmalonic acid, and succinic acid) and fecal metabolites (protocatechuic acid) were negatively associated (beta -1.373 to -.016, pFDR < 0.001-0.031; beta -1.008 to -.071, pFDR 0.005-0.033), while plasma metabolites (isovaleric acid, isovalerylcarnitine, l-glutamic acid, and pyroglutamic acid) and fecal metabolites (3-aminoisobutanoic acid, butyric acid, N-acetylneuraminic acid, octanoylcarnitine, oleoylcarnitine, palmitoylcarnitine, stearoylcarnitine, taurochenodesoxycholic acid, and taurodeoxycholic acid) exhibited positive associations with BMI, BMIZ, and body fat distribution (beta .023-2.396, pFDR < 0.001; beta .014-1.736, pFDR < 0.001-0.049). Conclusion: Plasma and fecal metabolites such as glutamine may serve as potential therapeutic targets for the development of obesity.