Characterizing the molecular signature of obesity through urine metabolomics in a large Chinese population.

Human obesity is a growing public health problem and has been considered as a pandemic non-communicable disease. Obesity and its related comorbidities have become a major health concern worldwide, but the metabolic factors underlying obesity are not well-understood. In the present study, we conducted large-scale untargeted metabolomics to clarify the metabolic links between obesity and the urinary metabolome. In total, 340 candidate urinary metabolites from 5831 Chinese individuals were identified by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QToF MS). The cross-sectional associations between urinary metabolites and body mass index (BMI) were examined. Height, weight, dietary and lifestyle habits of the participants were collected by questionnaire. The urinary metabolome was profiled by LC-QToF MS. The potential associations were evaluated by multiple linear regression adjusted for age and gender. Results revealed that 32 urinary metabolites were significantly associated with BMI, including 16 amino acids and peptides, 3 nucleotides, 1 carbohydrate, 1 lipid, 7 food components, and 4 exposure chemicals (Q < 0.01). Many of these potential associations have not been reported previously, including several peptides and exposure chemicals. In total, 59 candidate metabolites were associated with BMI at the P < 0.05 level. These findings provide a comprehensive view of metabolic phenotyping of obesity in the Chinese population. The untargeted metabolomic results suggest a broadly modifiable metabolic profile during the progress of obesity for future research.