Emulsifiers and gut bacteria in lab tests
What it found
In lab tests using human gut bacteria, most of 20 common emulsifiers changed the bacteria in ways that could promote gut inflammation.
Some, like soy lecithin and mono- and diglycerides, had no clear effect.
What they found
Animal and lab studies
Bacterial density changes
Some emulsifiers increased bacterial density, including glycerol stearate, sorbitan monostearate, carrageenans, guar gum, and maltodextrin. Others, like agar, DATEM, HPMC, and glyceryl oleate, caused a lasting decrease in bacterial density.
Bacterial composition changes
Many emulsifiers changed the types of bacteria present. For example, CMC, P80, maltodextrin, propylene glycol alginate, kappa carrageenan, gum arabic, and xanthan, guar, and locust bean gums all significantly altered the bacterial community. Some changes were not reversible after the emulsifier was removed.
Pro-inflammatory molecules
Several emulsifiers increased levels of molecules that can trigger inflammation, such as flagellin and lipopolysaccharide. Carrageenans, xanthan gum, guar gum, and locust bean gum raised flagellin, while maltodextrin and others raised lipopolysaccharide.
Gene activity changes
Most emulsifiers changed the activity of bacterial genes. P80, maltodextrin, propylene glycol alginate, kappa and lambda carrageenans, gum arabic, guar gum, DATEM, and glyceryl stearate had significant effects on gene expression.
Some emulsifiers had little effect
Soy lecithin and mono- and diglycerides did not show a clear impact on the gut bacteria in this lab model. Sunflower lecithin, however, increased flagellin levels during treatment.
What the authors conclude
“These results indicate that numerous, but not all, commonly used emulsifiers can directly alter gut microbiota in a manner expected to promote intestinal inflammation.”
Also in their conclusions
- They conclude that most, but not all, of the emulsifiers tested can directly alter gut bacteria in ways that would be expected to promote intestinal inflammation.
- They suggest that clinical trials are needed to reduce the use of the most detrimental compounds and to favor emulsifying agents with no or low impact on gut bacteria.
- They also note that future studies should test how these emulsifiers affect bacteria from different people and in combination with each other.
How it was done
The authors wanted to find out whether emulsifiers other than the well-studied carboxymethylcellulose and polysorbate 80 also affect gut bacteria. They were concerned because emulsifiers are common in processed foods and may play a role in chronic inflammatory diseases.
They grew human gut bacteria from one healthy donor in a lab model called MiniBioReactor Arrays. They tested 20 different emulsifiers at 0.1% for 144 hours, then followed the bacteria for another 58 hours without the emulsifiers. They measured bacterial density, composition, gene activity, and molecules that can trigger inflammation.
What it can’t tell you
- This was a lab study using gut bacteria from one healthy person, so it cannot show what happens in people eating these emulsifiers.
- The study cannot show whether the changes in bacteria would actually cause inflammation or disease in a living person.
- It also cannot tell us about long-term effects or how different people might respond.
Who paid
- Funding
- Funded by NIDDK NIH HHS (from the PubMed record).
- Conflicts
- The authors declare that they have no competing interests.
- Authors work at
- Université de Paris, France; Georgia State University, USA
The paper
- Title
- Direct impact of commonly used dietary emulsifiers on human gut microbiota
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Naimi S, Viennois E, Gewirtz AT, Chassaing B (2021). Direct impact of commonly used dietary emulsifiers on human gut microbiota. Microbiome. doi:10.1186/s40168-020-00996-6Free full textPubMed 33752754DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error