Association Between Plant-Based Diets and Metabolic Syndrome in Zhejiang, China: A Cross-Sectional Study

<b>Background/Objectives:</b> Plant-based diets are associated with reduced chronic disease risk, though regional variations persist. In Zhejiang, China, where plant-based food intake is high, this study aimed to explore the association between plant-based diets and metabolic syndrome (MetS) in adults aged 35-75. <b>Methods:</b> This cross-sectional study utilized data from the 2024 Zhejiang Nutrition and Health Survey (ZJNHS). Three plant-based diet indices were calculated: the overall plant-based diet index (PDI), healthy plant-based diet index (hPDI), and unhealthy plant-based diet index (uPDI). Multivariate logistic regression models evaluated associations between diet index quintiles and MetS and its components. <b>Results:</b> Among the 4695 participants included in the study, 23.9% (<i>n</i> = 1122) had MetS. After adjusting for demographic and lifestyle factors, individuals in the highest uPDI quintile showed a significantly higher MetS risk compared to the lowest quintile (OR = 1.37, 95% CI: 1.08-1.73, <i>p</i>-trend = 0.013). Subgroup analyses revealed significant gender interaction (<i>p</i> for interaction < 0.001), with women exhibiting elevated MetS risk (OR = 1.03, 95% CI: 1.01-1.04, <i>p</i> < 0.001). For MetS components, the highest uPDI quintile was associated with increased risks of abdominal obesity (OR = 1.32, 95% CI: 1.05-1.66; <i>p</i>-trend = 0.032), elevated blood pressure (OR = 1.41, 95% CI: 1.12-1.78; <i>p</i>-trend = 0.003), and elevated fasting glucose (OR = 1.27, 95% CI: 1.01-1.59; <i>p</i>-trend = 0.037). <b>Conclusions:</b> Unhealthy plant-based foods are associated with increased MetS risk, particularly in women. Reducing intake of such foods, considering sex differences, and implementing precision nutrition interventions are essential.