Childhood obesity is associated with changes in the serum metabolite profile.

Objective: The human serum metabolite profile is reflective of metabolic processes, including pathophysiological changes characteristic of diseases. Therefore, investigation of serum metabolite concentrations in obese children might give new insights into biological mechanisms associated with childhood obesity. Methods: Serum samples of 80 obese and 40 normalweight children between 6 and 15 years of age were analyzed using a mass spectrometrybased metabolomics approach targeting 163 metabolites. Metabolite concentrations and metabolite ratios were compared between obese and normal-weight children as well as between children of different pubertal stages. Results: Metabolite concentration profiles of obese children could be distinguished from those of normal-weight children. After correction for multiple testing, we observed 14 metabolites (glutamine, methionine, proline, nine phospholipids, and two acylcarnitines, p ! 3.8 ! 10 –4 ) and 69 metabolite ratios ( p ! 6.0 ! 10 –6 ) to be significantly altered in obese children. The identified metabolite markers are indicative of oxidative stress and of changes in sphingomyelin metabolism, in -oxidation, and in pathways associated with energy expenditure. In contrast, pubertal stage was not associated with