Monday, November 07, 2016

Common food additive promotes colon cancer in mice

https://www.eurekalert.org/pub_releases/2016-11/gsu-cfa110216.php

Public Release: 7-Nov-2016
Common food additive promotes colon cancer in mice
Georgia State University

Emulsifiers, which are added to most processed foods to aid texture and extend shelf life, can alter intestinal bacteria in a manner that promotes intestinal inflammation and colorectal cancer, according to a new study.

The findings, published in the journal Cancer Research, show regular consumption of dietary emulsifiers in mice exacerbated tumor development. The study was led by Drs. Emilie Viennois, Didier Merlin, Andrew T. Gewirtz and Benoit Chassaing, researchers in Georgia State University's Institute for Biomedical Sciences.

Colorectal cancer, the fourth leading cause of cancer-related deaths worldwide, was responsible for about 700,000 deaths in 2012. There is increasing awareness that the intestinal microbiota, the vast, diverse population of microorganisms that inhabits the human intestines, play a role in driving colorectal cancer.

The microbiota is also a key factor in driving Crohn's disease and ulcerative colitis, the two most common forms of inflammatory bowel disease (IBD). IBD is known to promote colon tumorigenesis and gave rise to the term "colitis-associated cancer." Low-grade inflammation, a condition more prevalent than IBD, was shown to be associated with altered gut microbiota composition and metabolic disease and is observed in many cases of colorectal cancer. These recent findings suggest dietary emulsifiers might be partially responsible for this association.

"The incidence of colorectal cancer has been markedly increasing since the mid-20th century," said Viennois, assistant professor in the Institute for Biomedical Sciences. "A key feature of this disease is the presence of an altered intestinal microbiota that creates a favorable niche for tumorigenesis."

"The dramatic increase in these diseases has occurred amidst constant human genetics, suggesting a pivotal role for an environmental factor," said Chassaing, assistant professor in the Institute for Biomedical Sciences.

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In this study, the team fed mice with two very commonly used emulsifiers, polysorbate 80 and carboxymethylcellulose, at doses seeking to model the broad consumption of the numerous emulsifiers that are incorporated into the majority of processed foods. Researchers observed that consuming emulsifiers drastically changed the species composition of the gut microbiota in a manner that made it more pro-inflammatory, creating a niche favoring cancer induction and development. Alterations in bacterial species resulted in bacteria expressing more flagellin and lipopolysaccharide, which activate pro-inflammatory gene expression by the immune system.

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