What are emulsifiers, and why are they in our food?

Have you noticed that the vinaigrette you made by shaking in a jar or whisking vigorously eventually separates with oil on the top and vinegar at the bottom? This is because you created a temporary emulsion between two liquids that can’t naturally blend without that physical force. As a result, they separate over time.

Emulsifiers are food additives used to prevent separation in the food industry. They also improve texture, extend shelf life, and enhance taste¹ and are among the most used additives globally. Over 6,000 food products in the UK contain an emulsifier, half containing multiples².

Do emulsifiers affect gut health?

Research has implicated that some emulsifiers may negatively impact gut health, particularly in relation to inflammatory bowel disease.

Initial research on emulsifiers and gut health came from animal models. One groundbreaking study found that in mice, two emulsifiers (carboxymethyl cellulose and polysorbate-80) altered the gut microbiome and thinned the protective mucus layer that keeps bacteria from getting too close to the gut lining³. This led to low-grade inflammation in healthy mice and triggered more severe gut inflammation in those genetically prone to it. The emulsifiers also promoted weight gain, blood sugar issues, and increased body fat — hallmarks of metabolic syndrome. Importantly, these effects were caused by changes in gut bacteria and were passed on to other mice through microbiome transplants.

While researching the impact of emulsifiers in mice is an essential first step, mouse models do not represent the complexity of health and disease in humans. In a randomised controlled study, healthy adults were given a diet containing a common emulsifier, carboxymethyl cellulose, for just 11 days⁴. They experienced increased abdominal discomfort after eating and noticeable changes in their gut microbiome compared to adults on an emulsifier-free diet. Specifically, microbiome diversity decreased, and they had lower levels of beneficial gut compounds like short-chain fatty acids. In some participants, the diet containing the emulsifier caused bacteria to move closer to the gut lining—a potential trigger for gut inflammation and a hallmark of inflammatory bowel disease. These findings suggest that even short-term exposure to emulsifiers like carboxymethyl cellulose may negatively impact gut health in some people.

Emulsifier-free diets and Crohn’s disease: The ADDapt Trial

The ADDapt Trial is the first randomised controlled trial to assess whether reducing emulsifiers in the diet could help people with active Crohn’s disease. Though the full results are currently under peer review before publication, early findings are promising.

Patients with mildly to moderately active Crohn’s disease who followed a low-emulsifier diet for 8 weeks were more than twice as likely to achieve symptomatic remission and have a 50% reduction in faecal calprotectin, a marker of intestinal inflammation⁵. Importantly, dietary analysis showed that the low-emulsifier diet did not compromise intake of most nutrients, and participants on a low-emulsifier diet reported a significant improvement in their food-related quality of life⁶.

These results suggest that a low-emulsifier diet may be a promising dietary approach for managing Crohn’s disease. However, any dietary changes, especially in people with chronic health conditions such as Crohn’s disease, should be made under the guidance of an experienced registered dietitian to ensure nutritional adequacy.