In 11 countries, regions with higher rates of specific DNA damage patterns linked to colibactin-producing bacteria also have higher rates of colorectal cancer, suggesting that differences in exposure to these bacteria may help explain why cancer rates vary by location.

We analyzed the available evidence and found that in 11 countries, regions with higher rates of a specific type of DNA damage—linked to bacteria that produce colibactin—also showed higher rates of colorectal cancer [1]. This pattern suggests that differences in exposure to these bacteria might be one factor among many that help explain why colorectal cancer rates vary from place to place. Colibactin is a substance made by certain gut bacteria that can cause changes in DNA, and these changes are sometimes seen in colorectal tumors. What we’ve found so far does not prove these bacteria cause cancer, but the consistent match between the DNA damage pattern and cancer rates across different regions is notable. No studies in our review contradicted this observation. The evidence we’ve reviewed leans toward a possible connection between colibactin-producing bacteria and regional differences in colorectal cancer rates, but we cannot say this is the only or main reason for those differences. Other factors like diet, lifestyle, genetics, or healthcare access could also play a role. Our current analysis is based on a single assertion supported by 48.0 data points, and while the pattern is consistent, more research would be needed to understand how strong or direct this link might be. For now, if you’re concerned about gut health and cancer risk, paying attention to overall diet and gut microbiome balance—through fiber, fermented foods, and avoiding excessive processed meats—may be a practical step.