Viennois, E et al. Cancer Research. Published online: 7 November 2016
The increased risks conferred by inflammatory bowel disease (IBD) to the development of colorectal cancer (CRC) gave rise to the term “colitis-associated cancer” and the concept that inflammation promotes colon tumorigenesis. A condition more common than IBD is low-grade inflammation, which correlates with altered gut microbiota composition and metabolic syndrome, both present in many cases of CRC.
Recent findings suggest that low-grade inflammation in the intestine is promoted by consumption of dietary emulsifiers, a ubiquitous component of processed foods which alter the composition of gut microbiota. Here, we demonstrate in a pre-clinical model of colitis-induced CRC that regular consumption of dietary emulsifiers carboxymethylcellulose or polysorbate-80 exacerbated tumor development. Enhanced tumor development was associated with an altered microbiota metagenome characterized by elevated levels of lipopolysaccharide and flagellin.
We found that emulsifier-induced alterations in the microbiome were necessary and sufficient to drive alterations in major proliferation and apoptosis signaling pathways thought to govern tumor development. Overall, our findings support the concept that perturbations in host-microbiota interactions that cause low-grade gut inflammation can promote colon carcinogenesis.
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Prof. Tom Sanders, Professor emeritus of Nutrition and Dietetics, King’s College London
“Overall this short-term mouse study has several limitations, including the extreme levels of additives the mice were fed, and that they had also been injected with a cancer-causing substance. We can’t assume this study is applicable to humans, so it shouldn’t be cause for concern.”
Prof. Sir Colin Berry, Emeritus Professor of Pathology, Queen Mary University London
“The significant limitations of this mouse study include that the quantities of emulsifiers fed to the mice were orders of magnitude greater than the likely dose for any human population. So, the amount of emulsifiers these mice were fed is not equivalent to what we have in our diets. These results do not demonstrate that emulsifiers in food make a contribution to the incidence of colorectal cancer in man.”
Read the full expert reactions here