Experts published a new study on Wednesday that found a rise in colorectal cancer in young adults could be linked to an increased exposure to a gut toxin that has been tied to the disease for decades.

The gut toxin, colibactin, has been linked to colon cancer since the mid-2000s, after studies found that it can cause distinct DNA damage to colon cells that’s difficult to repair. The damage can eventually lead to colon cancer. The toxin can be caused by harmful bacteria such as E.coli, Klebsiella pneumoniae and Citrobacter koseri. 

Researchers at the University of California San Diego found in their study, which was published in the journal Nature, that the damage is prevalent in people who developed the cancer under the age of 40. 

“Around 50% of early-onset colorectal cancers in individuals under 40 carried the distinctive signature of colibactin exposure,” senior study author Ludmil Alexandrov told NBC News.

The study examined the DNA of colorectal cancer tumors that were collected from 981 patients in 11 countries. It found that colibactin-related mutations were over three times more common in patients under the age of 40, compared with those over 70. 

The research also indicated that colibactin’s damaging effects could begin in childhood, even in the first decade of a person's life. Alexandrov said that several things could be causing this, including early-life antibiotic use; dietary shifts like reduced fiber consumption and an increase in processed foods; and reduced breastfeeding, among others.

“Collectively these shifts may be tipping the balance towards early-life acquisition of these microbes," he said.

Alexandrov said he and his research partners plan to develop a noninvasive test over the next few years that uses stool samples to determine whether people have had prior exposure to harmful bacteria. 

Misty Severi is a news reporter for Just The News. You can follow her on X for more coverage.