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According to a new Canadian study, certain intestinal bacteria could promote the development of colorectal cancer. The researchers also advise against certain supplements that could promote their growth.
Certain foods, a genetic predisposition or even obesity… The risk factors for colorectal cancer are well known to doctors. Canadian researchers have however looked into the trail of bacteria, contained in our intestines.
Bacteria known as “E.coli pks+”
Canadian scientists from the University of Montreal therefore chose to take a closer look at E. coli pks+ and its prevalence in Quebec both in healthy people and in those with colorectal cancer.
Result: 42% of healthy people had E. coli pks+ in their intestines, compared to 46% of people with colorectal cancer.
Bacteria that produce colibactin
These bacteria produce colibactin, a toxin that causes double-strand breaks in the DNA of host cells. This leads to higher mutation rates, which actually increases the likelihood of intestinal tumors. “Almost all previous studies have found higher levels of colibactin-producing bacteria in people with colorectal cancer“explains Manon Oliero, having worked on this study.
“Since we know that these pathogenic bacteria promote the development of colorectal cancer, it would be useful to know if an apparently healthy individual harbors them, and if so to suggest dietary or medical interventions to regulate bacteria levels.” .
In another study, experts continued their research to determine which nutritional supplements had effects on the growth of these bacteria and their production of colibactin.
Result: they realized that inulin, an over-the-counter dietary fiber in pharmacies, presented as a “prebiotic that feeds the healthy bacteria in your intestine”, causes the growth of pks E. Coli and therefore its production of colibactin.
This effect has been observed in vitro, but also on a mouse model of colorectal cancer colonized by pks+ E. coli and the first elements of research carried out on pks+ E. coli isolated from human stool confirm this effect: the majority of strains are capable to use inulin to increase their growth.
“This means that we must be careful when considering inulin supplementation for people colonized with pks + E. coli” estimates Manon Oliero. “We need to keep in mind the high prevalence of pks+ E. coli in healthy people, not just those with colorectal cancer.”