A common genetic variant that affects one in three people significantly increases the risk of colorectal cancer from the consumption of red meat and processed meat, according to a study presented Oct. 24 at the annual American Society of Human Genetics 2013 meeting.

According to a release from the University of Southern California, the study also reveals another specific genetic variation that appears to modify whether eating more vegetables, fruits and fibre actually lowers colorectal cancer risk.

“Diet is a modifiable risk factor for colorectal cancer. Our study is the first to understand whether some individuals are at higher or lower risk based on their genomic profile,” lead author Jane Figueiredo of USC said in the release.

“But we are not saying that if you don’t have the genetic variant that you should eat all the red meat you’d like,” Figueiredo added. “People with the genetic variant allele have an even higher increased risk of colorectal cancer if they consume high levels of processed meat, but the baseline risk associated with meat is already pretty bad.”

The researchers speculate that the digestion of processed meat may promote an immunological or inflammatory response that may trigger tumour development.

The researchers said that for those with another genetic variant, eating fruits and vegetables may provide even higher-than-normal protection against colorectal cancer.