Editorial: Emulsifiers and thickeners in our food—Do they alter gut permeability? Authors' reply

The relationship between dietary emulsifiers and Crohn's disease is intriguing and warrants continuing exploration. It may present information not only on pathogenesis and preventive strategies,¹ but also on dietary advice to control inflammation in patients with established Crohn's disease.² The emulsifier story has excited many. The European Society for Clinical Nutrition and the International Organisation for the Study of IBD have concerningly translated preclinical data to ‘evidence-based’ clinical advice for patients with Crohn's disease to avoid foods with added emulsifiers.^{3, 4} This dietary advice is not simple to implement for people living with Crohn's disease, since there are over 40 different emulsifiers in our food supply identified on ingredients lists on packaged food as either additive numbers or in expanded form. Over-restriction of many packaged foods will have considerable effects on food-related quality of life and psychosocial interactions, and is impractical in our modern world.

The editorial from Reid and Spiller⁵ on our study regarding the effects of diets varying in emulsifier content on intestinal barrier function⁶ has highlighted the gulf between the preclinical IBD models and how to establish the type of evidence that can be validly translated to dietary recommendations. Reid and Spiller recommend a scientist's reductionist approach to study single emulsifiers to determine their biological effects. We have taken the clinically translatable dietetic approach to studying emulsifiers as a group in the existing food supply. Both approaches are required for progressing our understanding of emulsifiers impacting Crohn's disease, but there are advantages to the dietetic approach. First, the emulsifiers examined represent what is actually in our food supply as opposed to choosing what Reid and Spiller correctly described as ‘obscure’ emulsifiers. Second, the doses to which research subjects are to be exposed in a high-emulsifier diet are those of the ‘real world’,⁷ as opposed to the large, pharmacological doses of specific emulsifiers that have been administered to mice and humans in studies to date.^8-10 Translating the effects of megadoses to those that might be reasonably consumed in a high-emulsifier diet is flawed and dangerous. More care in dosing has to be taken if the results are to be meaningfully applied to dietary management. Third, the concept that individual emulsifiers will work similarly when not incorporated in food and not interact with other emulsifiers is oversimplified and untested. Fourth, as Reid and Spiller commented, the heterogeneity in emulsifier action in the gut is important to consider, with some thickeners potentially having a beneficial effect.

Studying intake of emulsifiers as they are found in the food supply enables information on their biological effect as a whole to be examined, and the effect of their minimisation in the diet determined. However, both research approaches are needed to identify the offending culprit(s) or the emulsifier(s) with benefit. To avoid demonisation of food components without evidence, suggestions of causal links from preclinical studies need to be evaluated in carefully designed diet-controlled human trials, and then, much awaited evaluation in patients with Crohn's disease. For now, do not feel guilty if you eat ice-cream!

Jessica A. Fitzpatrick: Writing – review and editing; conceptualization. Peter R. Gibson: Writing – review and editing; conceptualization. Emma P. Halmos: Writing – review and editing; conceptualization.

There was no funding support for this manuscript.

This article is linked to Fitzpatrick et al papers. To view these articles, visit https://doi.org/10.1111/apt.18172 and https://doi.org/10.1111/apt.18222