Gut Training vs. Harmful Food Emulsifiers

In a new study, mice with immune systems that had been trained against the microbial protein flagellin did not experience the usual negative consequences of consuming food additive emulsifiers, pointing to a potential new strategy to battle many chronic inflammatory disorders.

These findings were published in the open-access journal PLOS Biology by Melissa Kordahi and Benoit Chassaing, Inserm researchers from the Institut Cochin and Université Paris Cité in France, and colleagues.

Dietary emulsifiers are additives added to processed foods to keep combined ingredients from separating. Previous study has revealed that consuming some emulsifiers may affect the gut microbiome—the microorganisms that normally exist in the gut—in such a way that some microbes are better able to breach the protective mucosal lining of the gut, potentially leading to persistent intestinal inflammation. Flagellin, a protein secreted by many bacteria that forms whip-like flagellae that allow them to move and so provide motility, may play a major role in inducing such inflammation.

Building on that earlier research, Kordahi and colleagues hypothesized that training the gut’s immune system to target flagellin—immunizing it against flagellin—may help protect against the detrimental downstream consequences of dietary emulsifiers consumption. To test this idea, they immunized mice to flagellin for several weeks and then fed them food containing two common dietary emulsifiers, carboxymethylcellulose (E466) and polysorbate 80 (E433).

They observed that the immunized mice did not experience invasion of microbes into their mucosal lining after ingesting emulsifiers. Moreover, immunization also appeared to protect against chronic intestinal inflammation and metabolic dysregulations normally observed after emulsifier ingestion.

The researchers also note that, after eating food with emulsifiers, the flagellin-immunized mice still experienced changes in the proportions of various microbe species that make up their gut microbiomes. This suggests that the protective effects of flagellin immunization may be related to its effects on microbe function and movement rather than solely an effect on microbiota composition.

More research will be needed to deepen the understanding of the potential use of flagellin immunization and how well these findings might translate to humans in the future. Nonetheless, this study suggests that flagellin immunization could be a potential new strategy to protect against inflammatory conditions that may be promoted by alterations in the host-microbiota interaction, such as inflammatory bowel disease, obesity, and type 2 diabetes.

Chassaing added, “This study suggests that targeted modulation of the intestinal microbiota can be an efficient way to prevent various chronic inflammatory conditions, such as metabolic deregulations occurring during the consumption of commonly used food additives.”