Combined analysis of data from 13 case-control studies previously conducted in populations with differing colorectal cancer rates and dietary practices. Original data records for 5287 case subjects with colorectal cancer and 10470 control subjects without disease were combined.
Risk decreased as fiber intake increased; relative risks were 0.79, 0.69, 0.63, and 0.53 for the four highest quintiles of intake compared with the lowest quintile (trend, P<.0001). The inverse association with fiber is seen in 12 of the 13 studies.This analysis provides substantive evidence that intake of fiber-rich foods is inversely related to risk of cancers of both the colon and rectum. Implications: If causality is assumed, we stimate that risk of colorectal cancer in the U.S. population could be reduced about 31% (50000 cases annually) by an average increase in fiber intake from food sources of about 13 g/d.
Dietary Intake of Fiber and Decreased Risk of Cancers of the Colon and Rectum: Evidence From the Combined Analysis of 13 Case-Control Studies