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    Dietary emulsifiers: are they all bad for our health?

    Team Benoit Chassaing

    Impact of dietary emulsifiers on human gut microbiota

     

    Researchers from Benoit Chassaing's team (Inserm U1016, CNRS, Université de Paris) have demonstrated that select dietary emulsifiers, additives widely used by the food industry to improve the organoleptic properties of processed products, have the potential to alter the composition and the function of the human gut microbiota leading to the promotion of its pro-inflammatory potential. In this study using an in vitro microbiota model, the researchers have indeed demonstrated that amongst the 20 emulsifying agents that were tested, a large majority induced a drastic and lasting effect on the composition and function of the microbiota. In addition, a limited number of additives had no significant impact on the composition and function of the gut microbiota, suggesting that these additives are not all equal in terms of impact on health, and that their usage should be favoured over other deleterious compounds. The results of this study are published in the journal Microbiome.

     

    According to previous work from this research team, two synthetic emulsifiers in particular, carboxymethylcellulose (CMC) and polysorbate-80 (P80), impact the intestinal microbiota in a manner that promotes chronic intestinal inflammation. Although many other additives are widely used by the food industry, very few studies have evaluated their impact on the gut microbiota and the development of chronic inflammatory diseases, such as inflammatory bowel diseases and metabolic deregulations.

    In this new study, Benoit Chassaing’s research team has examined the impact of 20 dietary emulsifiers on the human gut microbiota using an in vitro microbiota model, the MiniBioReactor Array (MBRA), allowing a longitudinal study on 48 microbiotas in parallel. Bacterial density and composition, as well as the metatranscriptome and pro-inflammatory potential of the gut microbiota were analysed longitudinally in this model simulating human intestinal conditions.

     

     

     

     

     

     

    Legend: Impact of 20 dietary emulsifiers on human gut microbiota using an in vitro microbiota model. A: Overview of the MiniBioReactor Array (MBRA) model installed within an anaerobic chamber. B: MBRA system after inoculation and stabilization with human microbiota. C: Global compositional and functional effects of dietary emulsifiers on the human microbiota. Heatmap visualization of the impact of dietary emulsifiers on bacterial density, microbiota composition, expression of microbiota-derived pro-inflammatory molecules, and metatranscriptome of the human gut microbiota.

     

     

     

     

     

     

     

     

     

    The results first demonstrated the efficiency of the MBRA model in maintaining a stable microbiota allowing the testing of several xenobiotics in parallel. In accordance with their previous studies, CMC and P80 induced an alteration of the composition and function of the intestinal microbiota. Strong adverse effects were observed in response to various carrageenans and gums, which drastically impacted the density, the composition and the pro-inflammatory potential of the microbiota. In addition, it has been observed that select emulsifying agents (soy lecithin, Mono- and diglycerides and Glyceryl oleate) have no significant impact on the human intestinal microbiota.

    Thus, these results demonstrate that many emulsifying agents added in ultra-processed food products are able to alter human intestinal microbiota, while some other additives appear to be harmless. Preclinical studies as well as clinical trials are now needed in order to assess the impact of these food additives on the predisposition to chronic inflammatory diseases.

     

    Reference

    Naimi, S., Viennois, E., Gewirtz, A.T. et al. Direct impact of commonly used dietary emulsifiers on human gut microbiota. Microbiome 9, 66 (2021).

     

    Researcher contact

    benoit.chassaing@inserm.fr