Inverse association between total bilirubin and metabolic syndrome in rural Korean women

Background: Chronic inflammation and oxidative stress are associated with the development of metabolic syndrome (MetS). Bilirubin is an antioxidant and has a protective effect against cardiovascular disease (CVD). The purpose of this study was to examine the association between total bilirubin levels and the prevalence of MetS in rural Korean women. Methods: This cross-sectional study included 5,266 women (>40 years) enrolled in the Korean Genomic Rural Cohort (KGRC). MetS was defined using the American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI) guidelines. Total bilirubin levels were categorized into quartiles. Results: Subjects in the upper quartiles of total bilirubin were younger and had lower waist circumferences, systolic blood pressure, and triglyceride levels and higher high-density lipoprotein cholesterol (HDL-C) concentrations. The overall prevalence of MetS was 39.0%. When the participants were categorized into quartiles by total bilirubin level, the prevalence of MetS according to increasing total bilirubin quartiles was 47.9%, 41.2%, 34.3%, and 32.7%, respectively. By comparison to the lowest quartile of total bilirubin (<0.61 mg/dL), the odds ratio (OR) (95% confidence interval [CI]) for MetS in the highest quartile of total bilirubin (≥0.94 mg/dL) was 0.63 (0.52-0.77) after adjusting for menopausal status, C-reactive protein (CRP) levels, insulin resistance, and other covariates. Conclusions: Total bilirubin level appears to be inversely associated with the prevalence of MetS in rural Korean women >40 years of age in the KGRC, even after adjusting for risk factors of MetS, including body mass index (BMI), menopausal status, CRP levels, and homeostasis model assessment of insulin resistance (HOMA-IR).