A new study adds to mounting evidence that following a Western-style diet dramatically increases the risk of developing colorectal cancer.

It’s well-known that our diets play an essential role in our health since the type of food we eat impacts our gut microbiota.

There’s growing evidence that a traditional Western diet leads to poor nutrition and a higher risk of developing health conditions, including obesity, diabetes and colorectal cancer.

This new evidence came from a recent study by researchers from the Brigham and Women’s Hospital. Published in Gastroenterology, the study looked at data from more than 134,000 participants from two nationwide prospective cohort studies.

Looking for bacterial strains that carry a distinct genetic island known as polyketide synthase (pks), the team found that the Western diet is associated with colorectal tumors containing high amounts of pks+ E. coli. Pks encodes an enzyme that causes mutations in cells.

“These findings support our hypothesis that Western-style diets increase colorectal cancer risk through its effect on pks+ E. coli,” said corresponding author Shuji Ogino, MD, PhD, MS, of the Program in Molecular Pathological Epidemiology in the Department of Pathology at Brigham.

“This is the first study to link the Western diet with specific pathogenic bacteria in cancer. Our next question is which component of western-style diet and lifestyle relates to colorectal cancer containing this bacterial species,” he added.

Past observational studies, meta-analyses and systematic reviews linked the Western diet with colon cancer. However, this study is the first of its kind.

Colorectal cancer, otherwise known as colon cancer, is a health condition that causes the cells in the colon or rectum to grow uncontrollably. This leads to symptoms like a change in bowel habits, increased constipation, or bouts of diarrhea.

It’s the third most common cancer diagnosed in patients in the U.S. and is the second most common cause of cancer deaths for both men and women, per the American Cancer Society.

Unfortunately, the exact cause of colon cancer is still largely unknown. But certain factors like smoking, excessive alcohol, and diets have been linked to the disease.