Research into the link between eating red meat and having colorectal cancer has relied on people who developed the condition being surveyed on their eating habits and researchers spotting associations between the two.
But no one really knew why it happened. In 2019, one team of researchers even said they had only a “low” degree of certainty that reducing consumption would prevent cancer deaths.
“When we say red meat is carcinogenic, and that it impacts incidence of cancer, there has to be some plausible way by which it does it,” Dana-Farber Cancer Institute oncologist Marios Giannakis, who led the new study, told Agence France-Presse.
Giannakis and his team, however, have now identified specific patterns of DNA damage triggered by diets rich in red meat — further implicating the food as a carcinogen. The study also indicates the possibility of detecting cancer early and designing new treatments.
The new study differs from previous ones because the participants kept track of their diets without knowing if they would someday have cancer. Previous studies waited until participants were sick to fill out a survey.
The researchers’ analysis found a mutation that had never before been identified but “was indicative of a type of DNA damage called ‘alkylation.’ "
It should be noted that not all cells with these mutations will become cancerous, and the mutation was seen in some healthy colon samples.
The mutation signature was significantly associated with eating both processed and unprocessed red meat prior to the patient’s cancer diagnosis. It was not, however, linked to the intake of poultry, fish or other lifestyle factors that were examined.
“With red meat, there are chemicals that can cause alkylation,” Giannakis said.
The signatures were strongly associated with the lower part of the bowels that leads to the anal canal, which is where research has suggested colon cancer linked to red meat mostly occurs.
In addition, the genes that were most affected by the alkylation patterns were the most common drivers of colorectal cancer when they mutate.
Taken as a whole, the multiple lines of evidence build up a compelling argument, Giannakis said.
He doesn’t suggest you cut out red meat entirely, however. Giannakis said the mutation could help identify people predisposed to colon cancer, so doctors can treat it earlier and possibly tell the patient their chance of recovery.
High levels of tumor alkylation damage were seen only in patients who ate, on average, more than 6 ounces of red meat a day, which is about two or more servings.
The study was published last week in the journal Cancer Discovery.
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