Emulsifiers and Gut Health: Evidence on Gut Barrier Function

Emulsifiers are food additives used to improve the texture, stability, and shelf life of many processed foods. They help ingredients that would normally separate, such as oil and water, remain mixed together. Some emulsifiers occur naturally, such as lecithin found in egg yolks and soybeans, while others are naturally derived from sources such as red seaweed (e.g., carrageenan) or made from vegetable oils or animal fats (e.g., mono- and diglycerides). There are also synthetic emulsifiers, such as carboxymethylcellulose (CMC) and polysorbate-80 (P80), which are produced through chemical processes to achieve specific functional properties. (1)

Over the past decade, emulsifiers have received increasing attention because research has suggested that some may influence the gut microbiome and the gut barrier function. This has led to headlines claiming that emulsifiers "cause leaky gut" or "damage the gut lining." However, emulsifiers are a diverse group of compounds with different chemical structures, and much of the evidence comes from laboratory and animal studies rather than human research. (2)

In this article, we will explore what some of the current evidence says about emulsifiers and gut barrier function, and what these findings may mean in practice.

What does the evidence say?

• In an in vitro model, polysorbate-80 increased the passage of Crohn's disease-associated bacteria across intestinal M cells, suggesting it may influence gut barrier function. However, as this was a laboratory study, the findings cannot be directly extrapolated to humans. (3)

• In a 12-week mouse study, chronic consumption of the emulsifiers carboxymethylcellulose (CMC) and polysorbate-80 (P80) altered the gut microbiota, reduced the protective mucus barrier, and increased intestinal permeability. These changes promoted low-grade intestinal inflammation and, in genetically susceptible mice, accelerated the development of colitis. As this was an animal study, the findings provide important mechanistic evidence but cannot be directly extrapolated to humans. (4)

• In a 2022 randomised controlled feeding trial in 16 healthy adults, consuming carboxymethylcellulose (CMC) for 11 days altered the gut microbiota, reduced beneficial bacterial metabolites, and caused bacteria to move closer to the intestinal lining in two participants. However, the study did not demonstrate widespread gut barrier dysfunction or clinical disease. Because it was small and short-term, further research is needed to determine whether these changes have long-term health implications. (5)

• In a 2024 single-blind, randomised crossover trial, healthy adults consumed both a high-emulsifier and a low-emulsifier diet, with most meals provided by the researchers. Under normal conditions, the high-emulsifier diet did not worsen gut barrier function or increase markers of intestinal injury or inflammation. However, following an acute physiological stress challenge, participants on the high-emulsifier diet experienced a greater increase in intestinal permeability, suggesting that higher emulsifier intake may increase the gut barrier's susceptibility to stress. Some limitations of the study, such as its short-term nature and the inclusion of only healthy adults, highlight the need for future studies. (6)

• In a randomised, double-blind, placebo-controlled crossover trial, 20 healthy young men consumed 250 mg of carrageenan twice daily or a placebo for two weeks, with intestinal permeability assessed using the lactulose–mannitol test as well as measurement of plasma zonulin. Compared with placebo, carrageenan increased intestinal permeability, as reflected by a higher lactulose–mannitol ratio and higher zonulin concentrations, although overall insulin sensitivity did not differ significantly between treatments. However, this was a short-term study, and researchers recognised the methodological limitations of plasma zonulin as a marker of gut permeability. (7)

  
  

What does that mean in practice?

• Not all emulsifiers are the same, and the current evidence does not suggest that all emulsifiers have the same effects on gut health.

• While some human studies suggest that certain emulsifiers may increase intestinal permeability or alter the gut microbiome, these studies were generally small and short-term. Larger, longer-term trials are needed before firm conclusions can be drawn.

• Foods containing emulsifiers are often ultra-processed foods, which may affect gut health for many reasons beyond emulsifier content alone, including differences in overall diet quality and the presence of multiple additives. (8) This makes it difficult to determine whether any observed effects are caused by the emulsifiers themselves or by the overall dietary pattern.

• A diet rich in minimally processed foods naturally reduces exposure to many food additives while providing fibre and other nutrients that support a healthy gut. Overall, there is currently no evidence to support eliminating all foods containing emulsifiers.

  
  

Key takeaway

Overall, the evaluated evidence suggests that some emulsifiers, particularly CMC, polysorbate-80, and possibly carrageenan, may influence gut barrier function. However, much of this evidence still comes from laboratory and animal studies, which cannot always be directly extrapolated to humans, while human research remains limited and sometimes inconsistent. At present, the most practical approach is to prioritise an overall healthy, minimally processed dietary pattern rather than avoiding all emulsifiers.

References:

1. De Siena M, Raoul P, Costantini L, Scarpellini E, Cintoni M, Gasbarrini A, et al. Food emulsifiers and metabolic syndrome: the role of the gut microbiota. Foods. 2022;11(15):2205. doi:10.3390/foods11152205.

2. Seto T, Grondin JA, Khan WI. Food additives: emerging detrimental roles on gut health. FASEB J. 2025;39(13):e70810. doi:10.1096/fj.202500737R.

3. Roberts CL, Keita AV, Duncan SH, O'Kennedy N, Söderholm JD, Rhodes JM, et al. Translocation of Crohn's disease Escherichia coli across M-cells: contrasting effects of soluble plant fibres and emulsifiers. Gut. 2010;59(10):1331-9. doi:10.1136/gut.2009.195370.

4. Chassaing B, Koren O, Goodrich JK, Poole AC, Srinivasan S, Ley RE, et al. Dietary emulsifiers impact the mouse gut microbiota promoting colitis and metabolic syndrome. Nature. 2015;519(7541):92-6. doi:10.1038/nature14232.

5. Chassaing B, Compher C, Bonhomme B, Liu Q, Tian Y, Walters W, et al. Randomized controlled-feeding study of dietary emulsifier carboxymethylcellulose reveals detrimental impacts on the gut microbiota and metabolome. Gastroenterology. 2022;162(3):743-56. doi:10.1053/j.gastro.2021.11.006.

6. Fitzpatrick JA, Gibson PR, Taylor KM, Halmos EP. The effect of dietary emulsifiers and thickeners on intestinal barrier function and its response to acute stress in healthy adult humans: a randomised controlled feeding study. Aliment Pharmacol Ther. 2024;60:863-75. doi:10.1111/apt.18172.

7. Wagner R, Buettner J, Heni M, Fritsche L, Kullmann S, Wagmüller M, et al. Carrageenan and insulin resistance in humans: a randomised double-blind cross-over trial. BMC Med. 2024;22(1):558. doi:10.1186/s12916-024-03771-8.

8. Whelan K, Bancil AS, Lindsay JO, et al. Ultra-processed foods and food additives in gut health and disease. Nat Rev Gastroenterol Hepatol. 2024;21:406-27. doi:10.1038/s41575-024-00893-5.

Disclaimer: This article is for educational purposes only and does not replace medical advice. Individual needs vary, and personalised guidance from a qualified healthcare professional is recommended for tailored support.