The Benefits of Dietary Fiber Intake on Reducing the Risk of Cancer: An Umbrella Review of Meta-analyses

Objective: The purpose of this study was to review previously published meta-analyses on the effectiveness of dietary fiber on reducing the incidence of cancer. Methods: An umbrella review of all published meta-analyses was performed. A PubMed search from January 1, 1980 to June 30, 2017 was conducted using the following search strategy: (fiber OR fibre) AND (meta-analysis OR systematic review) AND (cancer OR carcinoma). Only English-language publications that provided quantitative statistical analysis on cancer were retrieved. Results: Nineteen meta-analyses comparing highest vs lowest dietary fiber intake were retrieved for inclusion in this umbrella review. There was a statistically significant reduction in the relative risk (RR) of colorectal, esophageal, gastric, and pancreatic cancer (RR = 0.52-0.88); however, statistically significant heterogeneity was observed in the meta-analyses on esophageal, gastric, and pancreatic cancer. There was a statistically significant reduction in the RR of breast cancer (RR = 0.85-0.93). Conclusion: This review suggests that those consuming the highest amounts of dietary fiber may benefit from a reduction in the incidence of developing colorectal cancer, and there also appears to be a small reduction in the incidence of breast cancer.