People who consume more dietary fiber have a lower risk of developing colon cancer compared to those who consume less, and this protective effect appears to be stronger for colon cancer than for rectal cancer.

We analyzed the available evidence and found that people who eat more dietary fiber appear to have a lower risk of developing colon cancer compared to those who eat less, and this link seems stronger for colon cancer than for rectal cancer [1]. The evidence we’ve reviewed so far includes 55 assertions supporting this pattern, with no assertions contradicting it. This doesn’t mean fiber prevents colon cancer outright, but the consistent pattern across many observations suggests that higher fiber intake may be more closely tied to reduced colon cancer risk than to reduced rectal cancer risk. Colon and rectal cancers are both part of colorectal cancer, but they occur in different parts of the large intestine, and the way fiber interacts with each area may differ. Fiber can help move waste through the gut faster, possibly reducing exposure to potential irritants, and it may also feed beneficial gut bacteria that produce protective compounds. These processes might affect the colon more than the rectum, though the exact reasons aren’t fully clear from the data we’ve reviewed. We don’t know why the difference exists, and we can’t say fiber is the direct cause of lower risk. The evidence we’ve seen doesn’t explain how much fiber is needed, what types work best, or whether other lifestyle factors play a role. Still, the pattern is consistent across many observations. If you’re looking to support your digestive health, eating more fiber-rich foods like beans, whole grains, vegetables, and fruits is a simple step that aligns with what we’ve found so far.