Emulsifiers in processed foods: Can we train the gut against them?

• Scientists have recently been focused on learning more about the gut microbiome and its role in overall health.
• The trillions of microorganisms in the gut help with a variety of important processes that help keep the body healthy.
• Researchers recently discovered that the mucosal immune system can be trained to protect against a specific protein, helping it to combat the negative effects of consuming foods containing added dietary emulsifiers, at least in mice.
• This could offer a potential new way to train the mucosal immune system to help protect against chronic inflammatory diseases such as type 2 diabetes and obesity.

Over the past few years, researchers have paid great attention to the gut microbiome and how it affects a person’s overall health.

From ensuring the body absorbs everything it needs—from consumed foods to helping the body defend against infection—it’s obvious that the trillions of bacteria and other microorganisms in the digestive tract play an important role in keeping a person healthy.

However, keeping the gut microbiome functioning well can sometimes be difficult as diet, medications, and environmental factors can negatively impact its balance.

Now, researchers from the Institut Cochin, INSERM &Université Paris Cité, France, have discovered via a mouse model that the mucosal immune system can be trained to protect against a specific protein, helping it to combat the negative effects of consuming foods containing added dietary emulsifiers.

This study was recently published in the journal PLOS Biology.

Why target the protein flagellin? 

For this study, Dr. Benoit Chassaing, Inserm principal investigator at the Institut Cochin, INSERM &Université Paris Cité, France, and his team decided to train the mucosal immune system against a specific protein called flagellin. This particular protein plays an important role in driving bacterial cell movement, which can potentially trigger inflammation in the body.

Additionally, when dietary emulsifiers cause changes in the gut microbiome, the protective mucosal lining of the gut may no longer be able to keep out bad microbes, potentially causing chronic intestinal inflammation.

“Microbiota encroachment is key,” Dr. Chassaing explained when asked why they decided to focus on flagellin. “And we know that flagella — (a) filamentous appendix expressed by microbiota members — is a very important motility factor for microbiota encroachment.”

Protecting against chronic intestinal inflammation

Using a mouse model, the researchers trained the mice’s mucosal immune system in the gut to target flagellin, granting it immunity from the protein. The mice were then fed food containing the common dietary emulsifiers carboxymethylcellulose and polysorbate 80.

The scientists found the flagellin-immunized mice did not experience an invasion of microbes into their gut mucosal lining after consuming the emulsifiers.

Additionally, researchers discovered that flagellin immunization appeared to help protect the mice from chronic intestinal inflammation and metabolic dysregulations typically seen after ingesting dietary emulsifiers.

“Our findings suggest that targeting flagellated bacteria within the intestinal tract could offer innovative ways to beneficially modulate the intestinal microbiota in order to protect against an array of microbiota-related chronic inflammatory diseases, such as inflammatory bowel diseases and metabolic disorders.”

— Dr. Benoit Chassaing

What are dietary emulsifiers? 

Everyone knows that oil and water do not usually mix together. However, in some processed and prepackaged foods, getting two or more substances that usually would not mix together to do so is required.

This is where dietary emulsifiers come in. These are food additives used to help combine food ingredients that do not naturally do so.

The U.S. Food and Drug Administration (FDA) approves the use of dietary emulsifiers in foods in the United States. The European Food Safety Authority (EFSA) also approves any food additives, including emulsifiers, used in foods in European countries.

Some commonly used dietary emulsifiers include:

• soy lecithin
• carrageenan
• guar gum
• gellan gum
• xanthan gum
• polysorbates
• fatty acids extracted from vegetable oil or animal fat

Dietary emulsifiers are used in a variety of foods, including:

• mayonnaise
• prepackaged breads and baked goods
• ice cream
• chocolates
• low fat spreads like margarine
• salad dressings
• shelf-stable frostings
• nut butters like peanut butter
• creamy sauces

Are dietary emulsifiers harmful? 

Although emulsifiers used in foods are generally considered safe, consuming too many through a diet high in processed and packaged foods can potentially be harmful to your health.

A study in March 2021 found dietary emulsifiers may be a new modifiable risk factor for colorectal cancer. Other research published in December 2022 suggested dietary emulsifiers can worsen food allergies.

And there have been previous studies looking at how dietary emulsifiers impact the gut microbiome. One study in November 2020 found emulsifiers can alter the composition and activity of the gut microbiota, while another study published in March 2021 found some emulsifiers can directly alter gut microbiota and promote inflammation of the intestines.

“Dietary emulsifiers (promote) functional alterations in the intestinal microbiota, especially the promotion of microbiota encroachment within the normally sterile mucus layer,” Dr. Chassaing, lead author of the study, explained to Medical News Today.

“This is also observed, in mice and in humans during soluble fiber deprivation (and) chronic inflammatory diseases [s]uggesting that this phenomenon is an important player of microbiota-associated diseases. Hence, developing an approach to inhibit/prevent microbiota encroachment could have numerous health benefits,” he added.

Lowering low-grade gut inflammation

MNT also spoke with Perri Halperin, clinical nutrition coordinator in the Department of Surgery, Bariatrics at Mt. Sinai Hospital, about this study.

She said it is important to have a way to combat potential detrimental effects on the gut from dietary emulsifiers because research has shown that select dietary emulsifiers can contribute to low-grade inflammation in the gut, which may result from the ability of said emulsifiers to affect the gut microbiota.

“A variety of chronic diseases such as obesity, metabolic syndrome, type 2 diabetes, and inflammatory bowel disease are associated with low-grade gut inflammation. Thus, the ability to combat the potential detrimental effects of ingesting dietary emulsifiers, namely their role in low-grade inflammation, could reduce chronic disease risk and occurrence.”
— Perri Halperin

“This research suggests that the use of microbiota-derived antigens to vaccinate against certain chronic diseases that involve alterations of the gut from food additives has potential,” Halperin added.

“By keeping motile bacteria in check, preventing microbiota encroachment, and promoting a generally less pro-inflammatory microbiota in humans, this could be a prophylactic/therapeutic approach to protect against a variety of inflammatory diseases,” she said.

As for what she would like to see as the next steps in this research, Halperin commented that this research does have limitations as it was conducted in animal subjects versus humans.

“Importantly, the regimen used in this study, with repeated injection of purified flagellin, is not applicable in clinical settings. More research is needed in order to harness the use of microbiota-derived antigens to vaccinate against chronic disease,” she added.

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