Does colibactin cause early mutations in colorectal cancer?

Colibactin is a toxin produced by certain strains of gut bacteria, and when it interacts with human cells, it can break DNA in a specific pattern. These breaks, if not repaired, can turn into permanent mutations — changes in the genetic code that may allow cells to grow uncontrollably. What we’ve seen so far is that this exact pattern of DNA damage shows up in tumors at their earliest detectable stages, which implies the toxin was active before the cancer fully developed.

It’s important to note that we don’t know yet if colibactin is the only cause, or if other factors are needed for cancer to form. We also don’t know how common this exposure is in the general population, or how it interacts with diet, genetics, or other gut bacteria. But based on what we’ve reviewed so far, the presence of colibactin-related DNA damage in early cancer changes is a consistent finding.

If you’re concerned about gut health and cancer risk, focusing on a diet rich in fiber, fermented foods, and plant diversity may help support a balanced microbiome — the community of bacteria living in your gut — though more research is needed to understand exactly how this affects colibactin-producing strains.