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  p  p  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