Scientists link emulsifiers in processed foods to allergy and immune disorders

From your pantry to your gut: Scientists reveal how everyday food additives could silently fuel allergies, gut disorders, and chronic inflammation.

Review: Food additives and their impact on human health. Image Credit: nau2018 / Shutterstock

In a review article published in the journal Allergologia et Immunopathologia, researchers discussed the potential health impacts of various food additives, with a particular focus on food allergies and inflammatory diseases.

Background

Excessive consumption of ultra-processed foods is a well-known risk factor for cardiometabolic diseases, including hypertension, dyslipidemia, type 2 diabetes, and obesity. Recent evidence has also linked ultra-processed food consumption with increased risk of overall cancer mortality, as well as cancer-specific mortality, especially ovarian cancer-related mortality.

Despite health adversities, consumption of these foods is increasing readily worldwide, especially in Western countries, as these products are highly palatable, ready for consumption, and inexpensive.

Ultra-processed foods contain high amounts of salt, sugar, saturated and trans fats, food additives, flavor enhancers, sweeteners, and preservatives. These ingredients make ultra-processed foods nutritionally poor and contribute to adverse health impacts associated with their consumption.

Regarding allergic reactions and intolerance associated with ultra-processed foods, recent studies have increasingly suggested the role of food additives in triggering food allergies and inflammation in vulnerable people.

Given the scarcity of information, the authors of this review aimed to investigate the relationship between the consumption of ultra-processed foods and the risk of inflammatory diseases, particularly allergic diseases.

They screened various electronic databases to identify recent articles (published since 2015) that reported the association between food additives and health risks. Following final screening and assessment, 43 articles were included in the review.

Review findings

Food additives, including flavor enhancers, artificial food colors, emulsifiers, stabilizers, thickeners, pH control agents, and preservatives, are widely used in the food industry to enhance the flavor, texture, color, and shelf life of various food products, including ultra-processed foods. These additives are either derived from natural sources (such as plants, animals, or minerals) or chemically synthesized.

The U.S. Food and Drug Administration (FDA) has recognized approximately 450 substances as Generally Recognized as Safe (GRAS) and approved another 3,000 food additives for use in food products. However, there is no regulatory mechanism for ongoing monitoring of their safety, and some of these additives have been found to have negative health impacts.

Flavor enhancers

The most commonly used flavor enhancers are hydrolyzed vegetable protein and monosodium glutamate (MSG). Although rare, MSG has been found to trigger allergic reactions in people with high sensitivity. However, the article notes that studies have often failed to reproduce these reactions under controlled conditions, and consistent evidence for MSG-triggered allergies remains limited.

Artificial food colors

Food additives such as annatto, carmine, and tartrazine are commonly used for coloring purposes. Existing evidence indicates that, in addition to triggering hives or swelling, annatto and carmine can induce severe allergic reactions (anaphylaxis) in some cases. Tartrazine may also cause hives in rare cases.

Emulsifiers, stabilizers, and thickeners

Lecithin, carrageenan, guar gum, and xanthan gum are examples of emulsifiers that are used in food products to stabilize mixtures and prevent separation. Carrageenan, guar gum, and xanthan gum are also used in food products as stabilizers and thickeners.

Studies have linked carrageenan and guar gum with gastrointestinal symptoms and rare allergic reactions. Specifically, carrageenan has been found to trigger inflammatory responses by binding to BCL10 (B-cell lymphoma/leukemia 10) and subsequently activating the NFkB pathway. It also increases CXCL-8 (IL-8) secretion, contributing to inflammatory cascades.

According to existing evidence, the negative health impacts of emulsifiers are associated with their ability to alter gut microbial diversity, increase the abundance of bacteria with pro-inflammatory potential, reduce the thickness of the intestinal mucosal lining, and increase intestinal permeability by disrupting tight junction proteins.

All these factors collectively induce the production of proinflammatory mediators and stimulate inflammatory pathways, leading to the development of metabolic, allergic, and autoimmune diseases.

Some emulsifiers, such as polysorbate 20 and polysorbate 80, have also been found to alter the expression of genes involved in various biological processes, including development, cell signaling, proliferation, apoptosis, and inflammatory response. Proteome pathway analysis has shown that these emulsifiers may trigger Th1- or Th2-type immune responses, suggesting an immunological mechanism linking emulsifiers to disease.

pH control agents, such as citric and lactic acid, are commonly used to regulate food acidity. Reactions to manufactured citric acid are rare, and lactic acid is generally well tolerated, although it may cause confusion in individuals with milk allergies when labeled with calcium-related terms.

Preservatives

Preservatives, including nitrates or nitrites and sulfites, are used in food products to extend shelf life and reduce spoilage. While nitrates or nitrites have been linked to allergic reactions, including hives and itching, sulfites have been found to trigger severe allergic reactions and worsen asthma symptoms.

Health adversities caused by food additives

Studies have linked some food emulsifiers, including carboxymethylcellulose and polysorbate 80, with the pathogenesis of inflammatory bowel disease (IBD). Regarding mode of action, the findings indicate that these emulsifiers can promote proinflammatory intestinal microbiota, disrupt gut mucosal architecture and intestinal barrier integrity, activate inflammatory pathways, and induce cell cycle arrest in individuals at a higher risk of developing IBD.

Animal studies have reported that in utero exposure of pup mice to polysorbate 80 can lead to disruption of intestinal barrier function, induction of low-grade inflammation, and gut dysbiosis characterized by increased abundance of pathogenic bacteria and reduced abundance of beneficial bacteria.

Since obesity is known to be closely associated with unhealthy diet and altered gut microbiota, food additive-induced gut dysbiosis is considered a major risk factor for obesity and other metabolic diseases.

In this context, evidence indicates that consumption of ultra-processed foods potentially increases the risk of obesity, metabolic syndrome, IBD, dyslipidemia, and dyspepsia (indigestion).

Unhealthy components present in ultra-processed foods, such as food additives, are known to increase the risk of eosinophilic esophagitis by disrupting the esophageal barrier and inducing inflammation. In particular, advanced glycation end-products (AGEs) present in processed foods may impair the esophageal mucosa, promoting allergic sensitization and inflammation.

Di-2-ethylhexyl phosphate (DEHP) and its primary toxic metabolite, mono-2-ethylhexyl phthalate (MEHP-AF), are the typical endocrine-disrupting chemicals with adverse health effects. The food emulsifier polysorbate 80 has been found to enhance the bioavailability of MEHP-AF by increasing its intestinal absorption.

Review highlights

The review identifies food emulsifiers as the most harmful food additive that can potentially increase the risk of food allergies and inflammatory diseases by altering gut microbiota, disrupting intestinal barrier integrity, and inducing inflammation.

The authors also note the importance of maintaining epithelial barrier function and microbial diversity as protective factors against food antigen translocation and immune dysregulation.

As mentioned by the authors, further research is needed to better understand the mechanisms driving the association between food additives and immunological diseases, and to develop strategies to mitigate potential risks.