Association of priori dietary patterns with metabolic syndrome and its components: a systematic review and meta-analysis.

BACKGROUND: Metabolic syndrome (MetS) poses an increasing threat to global health. Dietary patterns are recognized as modifiable factors related to MetS, but evidence on the associations of a priori dietary patterns with MetS remains inconsistent across studies. METHODS: Embase, Web of Science, and PubMed were systematically searched up to March 20, 2025. Observational studies (cross-sectional, cohort, case-control) exploring the associations of a priori dietary patterns with MetS were included. The Joanna Briggs Institute tool and the Newcastle-Ottawa Scale were applied to assess the study quality. The certainty of the pooled evidence was assessed via the Grading of Recommendations Assessment, Development and Evaluation approach. A random-effects model was adopted to combine effect sizes. RESULTS: Thirty-nine studies were incorporated. Categorical analyses showed that higher dietary inflammatory index (DII) was associated with higher prevalence of MetS (odds ratio [OR] [95% confidence interval (CI)]: 1.33 [1.23-1.43], p < 0.001). Higher Oxidative Balance Score (OBS) was associated with lower prevalence of MetS (0.48 [0.41-0.58], p < 0.001). High adherence to the Mediterranean diet (MD), Dietary Approaches to Stop Hypertension (DASH), Dietary Diversity Score (DDS), or Healthy Eating Index (HEI) showed no significant associations with MetS. Given the limited data for continuous variables, continuous analyses were only conducted for OBS and MD. These continuous analyses indicated that higher OBS and MD scores were associated with lower prevalence of MetS (for OBS: 0.94 [0.92-0.96], p < 0.001; for MD: 0.89 [0.83-0.96], p = 0.001). CONCLUSION: A priori dietary patterns are closely associated with MetS. Promoting anti-inflammatory, antioxidant-rich, and Mediterranean-style eating patterns may be associated with lower prevalence of MetS, which could provide potential implications for the prevention and management of MetS. However, causal inference remains limited, and further prospective studies and trials are needed. SYSTEMATIC REVIEW REGISTRATION: Unique identifier: CRD420251043513, https://www.crd.york.ac.uk/PROSPERO/view/CRD420251043513.