Association between Urinary 3-hydroxypropyl Mercapturic Acid Levels and Metabolic Syndrome: Increased Risk in Female Non-smokers

Acrolein, a toxic aldehyde from smoking and environmental sources, has been linked to metabolic disturbances, but its relationship with metabolic syndrome (MetS) in non-smokers, especially women, is unclear. This study examined the association between urinary 3-hydroxypropyl mercapturic acid (3-HPMA) and MetS. This study analyzed 1,525 Korean adults from the Korea National Health and Nutrition Examination Survey, using sampling weights to account for its complex design. The participants were classified according to their MetS and smoking status, with subgroup analyses performed on non-smoking women. The associations between the urinary 3-HPMA and MetS scores were assessed using complex-sample general linear models with stepwise covariate adjustment. MetS-positive participants were significantly older, had a higher BMI, and exhibited higher urinary 3-HPMA levels than the MetS-negative participants. Daily smokers had higher 3-HPMA and MetS scores than non-smokers. Among the non-smokers, male participants showed no significant association between the 3-HPMA and MetS scores (P=0.804). By contrast, female non-smokers exhibited a significant positive association between the 3-HPMA and MetS scores, even after full adjustment in Model 3 (B=0.0141, 95% CI: 0.0031~0.0252, P=0.012). Environmental or endogenous acrolein exposure may contribute to the metabolic risk. Importantly, the association was evident only in non-smoking women, highlighting acrolein as a potential sex-specific factor in MetS development and underscoring the need for further research into its underlying mechanisms.