Editorial: Inflammatory Bowel Disease and Dietary Emulsifiers—A Conundrum That Continues

The impact of ultra-processed foods (UPFs) on inflammatory bowel disease (IBD) pathogenesis is increasingly recognised [1-3]. Clinical and preclinical studies link UPFs, including dietary emulsifiers, to dysbiosis, mucous layer disruption and immune activation [1, 2]. Since the increasing consumption of processed foods has been linked to increased incidence and prevalence of chronic disease, including IBD, the influence of UPF consumption on IBD-related outcomes is of major interest [1].

Fitzpatrick et al. [4] conducted a double-blinded randomised controlled trial in patients with active ileal Crohn's disease. Nineteen participants received either a high emulsifier diet (HED) or low emulsifier diet (LED) for 4 weeks. There were no significant differences in improvement in clinical disease activity, intestinal ultrasound findings or quality of life between the two groups. The authors concluded that the findings did not support the current recommendations for patients to avoid dietary emulsifiers.

Controlled feeding studies, such as this [4], provide an opportunity to isolate and assess the impact of specific food components. Notable strengths of this study included its blinded, randomised design; carefully formulated dietary interventions; and integration of clinical biomarkers and patient-reported outcomes to evaluate effectiveness.

The study also had several limitations. The small sample and high dropout rate (> 20%, with 10 patients on HED and nine on LED) limit the ability to draw definitive conclusions about the impact of emulsifiers versus other dietary components, or disease activity on gastrointestinal symptoms. Moreover, the short dietary intervention period may not have been long enough to see the full impact of the emulsifiers, especially in this small cohort.

Moreover, the study lacked formal assessment of dietary quality and other potential confounding dietary components. While the diets followed ‘healthy eating guidelines’, standardised dietary assessment tools such as the Healthy Eating Index or the Mediterranean Diet Score could have identified differences beyond emulsifier content [5-9]. Emulsifier quantification was also limited with no distinction between naturally occurring and synthetic emulsifiers (e.g., polysorbate 80 vs. egg yolks), despite their potential for differing effects on the microbiome [10]. Furthermore, NOVA classification of the actual rather than recommended food intake would have provided a more accurate diet assessment.

Despite the reported high adherence to the diets based on food diaries, it remains unclear how many patients were fully compliant during the intervention. Assessing dietary compliance is crucial, particularly in a study with so few participants. Additionally, while the diets were designed to meet energy requirements, all patients experienced weight loss, which may be secondary to dietary underreporting and may have led to a reduction in emulsifier consumption as well.

Larger, prospective studies with objective outcomes, such as microbial diversity, intestinal permeability and endoscopic healing, and with validated measures of dietary adherence are needed to better understand the link between emulsifiers and inflammation. Distinguishing between natural and synthetic emulsifiers will also guide clinical recommendations. Until then, patients should be counselled on the variability in the literature and advised to avoid UPFs with emulsifiers when possible.

Stephanie Gold: conceptualization, methodology, writing – original draft, writing – review and editing. Natasha Haskey: conceptualization, writing – review and editing. Maitreyi Raman: conceptualization, methodology, writing – review and editing.

S.G.: Nestle Nutrition Institute Fellow 2023, supported by a Crohn's and Colitis Foundation Career Development Award, Medical Board Member of Nutritional Therapy for IBD. M.R.: Speaker Fees: Fresenius Kabi, AbbVie. Grant Support: Pfizer, AbbVie, Johnson & Johnson. LyfeMD—Cofounder, CMO. N.H.: Medical Board Member of Nutritional Therapy for IBD.

This article is linked to Fitzpatrick et al papers. To view these articles, visit https://doi.org/10.1111/apt.70041 and https://doi.org/10.1111/apt.70148.