No association between fiber intake and prostate cancer risk: a meta-analysis of epidemiological studies

BACKGROUND The findings of epidemiologic studies on the association between fiber intake and prostate cancer risk remain conflicting. We aimed to examine this association by conducting a meta-analysis of epidemiological studies. METHODS Relevant studies were identified by PubMed (1966 to March 2015) and Embase (1974 to March 2015) database search through March 2015. We included epidemiological studies that reported relative risks (RRs) or odds ratios (ORs) with 95% confidence intervals (CIs) for the association between dietary fiber intake and prostate cancer risk. Random effects models were used to calculate the summary risk estimates. RESULTS For the highest compared with the lowest dietary fiber intake, a significantly decreased risk with prostate cancer was observed in case-control studies (OR = 0.82; 95% CI, 0.68-0.96), but not in cohort studies (RR = 0.94; 95% CI, 0.77-1.11). The combined risk estimate of all studies was 0.89 (95% CI, 0.77, 1.01). A significant heterogeneity was observed across studies (p = 0.005). There was no evidence of significant publication bias based on Begg's funnel plot (p = 0.753) or Egger's test (p = 0.946). CONCLUSIONS This meta-analysis suggests the absence of evidence for association between dietary fiber intake and prostate cancer risk.