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 I-2 = 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; I-2 = 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 I-2 = 72.0 %) in cross-sectional studies, and the RR was 0.96 (95 % CI 0.53, 1.73; P for heterogeneity = 0.102; I-2 = 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.