Colon cancer is increasingly affecting younger adults—**1 in 5 new cases now occurs in people under 54**. A new *Nature* study may explain why: researchers found a strong link between early-onset colorectal cancer and **colibactin**, a DNA-damaging toxin made by some strains of *E. coli*.

“Younger patients were three times more likely to have colibactin-related mutations,” especially those diagnosed under 40. By examining nearly 1,000 tumor samples from 11 countries, scientists found that many mutations may trace back to **gut damage before age 10**, putting some people decades “ahead of schedule” for cancer.

About **20–30% of people carry colibactin-producing bacteria**, but not all get cancer. Researchers believe early-life factors—**birth method, antibiotics, diet, and exposure to processed foods**—may explain why some are more vulnerable.

To fight this, scientists are exploring new tools: **targeted probiotics**, and **stool tests to detect colibactin mutations** early. For now, they recommend staying active, following a **Mediterranean-style diet**, and not ignoring persistent symptoms.

“Understanding how gut bacteria affect cancer risk may help us prevent it before it starts.”