Dietary fiber intake and risk of metabolic syndrome: A meta-analysis of observational studies

Background & aims: Epidemiological studies show inconsistent findings on the association of dietary fiber intake with risk of metabolic syndrome (MetS). Herein, we aim to conduct a meta-analysis of published studies to determine the role of dietary fiber in prevention of MetS. Methods: A systematical search in PubMed and Embase databases through December 2016, together with reference scrutiny of relevant literature, was performed to identify studies for inclusion. We aggregated the odds ratios (ORs) with 95% confidence intervals (Cls) of MetS using a random effect model. Dose response relationship between fiber intake and MetS was also evaluated. Results: This meta-analysis included 8 cross-sectional and 3 cohort studies, totaling 28,241 participants and 9140 MetS cases. The highest versus lowest fiber intake was associated with a reduced risk of MetS (OR: 0.85, 95% CI: 0.79-0.92; P = 0.005), with moderate heterogeneity (12 = 64%, P = 0.001) across studies. The benefit of fiber intake was significant among cross-sectional studies (OR: 0.85, 95% CI: 0.78 -0.92; P < 0.001) but not among cohort studies (OR: 0.86, 95% Cl: 0.70-1.06; P = 0.16). In dose response analysis, we found a curvilinear relationship between fiber consumption and prevalence of MetS. Compared with non-fiber intake, the ORs (95% CIs) of MetS across fiber intake levels were 0.85 (0.79 -0.91), 0.76 (0.67-0.85), 0.73 (0.65-0.83), and 0.73 (0.65-0.82) for 10, 20, 30, and 40 g/d, respectively. Conclusions: Dietary fiber intake is associated with less likelihood of having MetS. Additional large, prospective studies are warranted to enhance our findings. (C) 2017 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.