Metabolic syndrome and dietary patterns: a systematic review and meta-analysis of observational studies

Purpose: Lifestyle is linked to the risk of developing metabolic syndrome (MetS); however, its relationship with dietary patterns remains unclear. This systematic review and meta-analysis aims to analyse the association of a posteriori dietary patterns with the metabolic syndrome. Methods: The PubMed, CINAHL and Scopus databases were searched for epidemiological studies of dietary patterns and MetS. The association between dietary patterns and MetS was estimated using a random-effects meta-analysis with 95 % confidence intervals (CIs). Results: A total of 28 cross-sectional studies and three cohort studies were included in the meta-analysis. In a comparison of the highest to the lowest category of prudent/healthy dietary patterns, the pooled odds ratio (OR) for MetS was 0.83 (95 % CI 0.76, 0.90; P for heterogeneity =0.0; and I² = 72.1 %) in cross-sectional studies, and the pooled relative risk (RR) for MetS in cohort studies was 0.91 (95 % CI 0.68, 1.21; P for heterogeneity =0.005; I² = 81.1 %). The pooled OR for MetS in a comparison of the highest to the lowest category of Western dietary patterns was 1.28 (95 % CI 1.17, 1.40; P for heterogeneity =0.0; and I² = 72.0 %) in cross-sectional studies, and the RR was 0.96 (95 % CI 0.53, 1.73; P for heterogeneity =0.102; I² = 62.6 %) in cohort studies. Conclusions: The results from cross-sectional studies showed that a prudent/healthy pattern is associated with a lower prevalence of MetS, whereas a Western/unhealthy is associated with an increased risk for MetS. Additional prospective studies are needed to confirm the association between dietary patterns and MetS.