Dietary fiber intake and risk of type 2 diabetes: a dose–response analysis of prospective studies

Observational studies suggest an association between dietary fiber intake and risk of type 2 diabetes, but the results are inconclusive. We conducted a meta-analysis of prospective studies evaluating the associations of dietary fiber intake and risk of type 2 diabetes. Relevant studies were identified by searching EMBASE (from 1974 to April 2013) and PubMed (from 1966 to April 2013). The fixed or random-effect model was selected based on the homogeneity test among studies. In addition, a 2-stage random-effects dose–response meta-analysis was performed. We identified 17 prospective cohort studies of dietary fiber intake and risk of type 2 diabetes involving 19,033 cases and 488,293 participants. The combined RR (95 % CI) of type 2 diabetes for intake of total dietary fiber, cereal fiber, fruit fiber and insoluble fiber was 0.81 (0.73–0.90), 0.77 (0.69–0.85), 0.94 (0.88–0.99) and 0.75 (0.63–0.89), respectively. A nonlinear relationship was found of total dietary fiber intake with risk of type 2 diabetes (Pfor nonlinearity < 0.01), and the RRs (95 % CI) of type 2 diabetes were 0.98 (0.90–1.06), 0.97 (0.87–1.07), 0.89 (0.80–0.99), 0.76 (0.65–0.88), and 0.66 (0.53–0.82) for 15, 20, 25, 30, and 35 g/day. The departure from nonlinear relationship was not significant (Pfor nonlinearity = 0.72), and the risk of type 2 diabetes decreased by 6 % (RR 0.94, 95 % CI 0.93–0.96) for 2 g/day increment in cereal fiber intake. Findings from this meta-analysis indicate that the intakes of dietary fiber may be inversely associated with risk of type 2 diabetes.