Associations of the unhealthy plant-based diet index with hsCRP and BMI in Korean adults
Background This study investigated the associations of the unhealthy Plant-based Diet Index (uPDI) with high-sensitivity C-reactive protein (hsCRP) and body mass index (BMI) using data from the 2022–2023 Korea National Health and Nutrition Examination Survey. Methods The study included adults aged 19–64 years, excluding individuals with implausible energy intake (<500 or >5,000 kcal/day), underweight status, or missing data, resulting in a final sample of 5,610 participants. The uPDI was calculated by summing energy-adjusted, quintile-based scores across 19 predefined food groups. Elevated hsCRP was defined as ≥3 mg/L, and obesity as BMI ≥ 25 kg/m2. Survey-weighted regression analyses were performed after adjustment for demographic and lifestyle covariates. Results Among women, higher uPDI scores were positively associated with both hsCRP (p < 0.001) and BMI (p < 0.001) in multivariable-adjusted linear regression models. Logistic regression analyses revealed that higher uPDI scores correlated with elevated hsCRP (odds ratio [OR]: 2.043; 95% confidence interval [CI], 1.298–3.217; P-trend = 0.006) and obesity (OR: 1.876; 95% CI, 1.440–2.444; P-trend < 0.001). In contrast, no significant associations were identified in men across any model. Conclusion Greater adherence to an unhealthy plant-based dietary pattern was associated with increased inflammation and adiposity among Korean women. While sensitivity analyses consistently supported these findings, the cross-sectional design means these results indicate associations, not causal relationships.