Phthalates, physical activity, and diet, which are the most strongly associated with obesity? A case-control study of Chinese children

Purpose Phthalate esters have been a research hotspot recently owing to potential obesogenic activity, but conflicting results have been reported. This case-control study was designed to investigate whether there was an association between phthalate metabolites and childhood obesity in China. Methods A total of 240 pairs of obese/overweight children and age- (±3 months) and gender-matched controls were recruited. Nine phthalate metabolites were analyzed in the first morning urine sample. Physical activity and dietary intake were recorded using validated questionnaires. Results In monofactor analysis, the levels of monomethyl phthalate (MMP) and monobutyl phthalate (MnBP) in controls were significantly higher than those of overweight/obese children ( p < 0.05). Moderate physical activity ( p = 0.004), consumption of vegetables, fruits, and tonic were significantly higher in controls (all p < 0.05), and consumption of fried food, western fast food, carbonated drinks, and juice were higher in cases (all p < 0.05). After adjusting for physical activity and dietary intake, neither MMP [OR = 0.825, (95% CI: 0.559–1.217)] nor MnBP [(OR = 0.808, 95% CI: 0.556–1.176)], were significantly associated with obesity. In all models, moderate physical activity was negatively associated and high glucose high fat dietary patterns were positively associated with the risk of childhood obesity ( p < 0.01). Conclusion Diet and physical activity, but not phthalate metabolites were associated with childhood obesity. Further studies are needed to verify our findings. The trial was registered at clinicaltrials.gov as NCT05622513.