Small Intestine Dilation Links to Food-Protein-Induced Enterocolitis Syndrome

A new study suggests the dilation of the small intestine is associated with adult Food-Protein-Induced Enterocolitis Syndrome (FPIES).1

“This study is the first to demonstrate the significant role of small intestinal dilatation in abdominal symptoms of adult FPIES,” study investigator Sho Watanabe, from the Soka Municipal Hospital in Japan, and colleagues wrote.

Food protein–induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy that manifests with gastrointestinal symptoms, though its anatomical origin and pathogenesis remain poorly understood. In one study, abdominal distention occurred in 81.8% of adults with FPIES, compared with 18.8% of those with gastrointestinal food allergy.2

Although abdominal distention is common in those with FPIES, symptoms vary between patients. In this study, investigators aimed to establish objective criteria for evaluating abdominal distension and to investigate the pathophysiology and anatomical origin of FPIES.1

The study included 26 adults (84.6% females, mean age: 42 years) with FPIES. Causative food includes seafood (crustacean: 23%; bivalve: 15.4%; fish: 11.5%), hen egg (15.4%), milk (11.5%), fruit (7.7%), meat (7.7%), vegetable (3.8%), and grains (3.8%). More than half of the participants (69.2%) had an allergy to multiple foods.1

The mean age of onset and at last reaction was 29.5 years and 41.5 years, respectively. Abdominal symptoms included abdominal pain (96.2%), diarrhea (69.2%), nausea (80.8%), vomiting (50%), and abdominal distention (92.3%). Among the sample, 50% had functional gastrointestinal disorder and 46.2% had eosinophilic gastrointestinal disease.1

Investigators crafted 8 questions about abdominal distension to help with its diagnosis:

1. Do you have a distressing feeling of bloating?
2. Do you have abdominal discomfort different from pain and nausea?
3. Do you have an indescribable, hard-to-express abdominal discomfort?
4. Do you have abdominal discomfort that you wish to be relieved by vomiting or defecation?
5. Do you have the sensation of wanting to vomit or defecate but can’t?
6. Do you have abdominal discomfort not relieved by vomiting or defecation?
7. Do you suffer from abdominal discomfort for more than 30 minutes in the restroom or bed?
8. Do you feel restless due to that abdominal discomfort?

The team developed an evaluation algorithm based on items with high positivity rates. Among these 8 questions, the ones with the highest positive rate were “Do you have abdominal discomfort that you wish to be relieved by vomiting or defecation?” (95.8%), “Do you suffer from that discomfort for more than 30 min kept in the restroom or bed?” (91.8%), “Do you have a distressing feeling of bloating?” (75%) and “Do you feel restless due to that abdominal discomfort?” (75%).1

With the algorithm, if a patient says yes to the question “Do you have distressing feeling of bloating?” then abdominal distension is confirmed. If the answer to “Do you have abdominal discomfort that you wish to be relieved by vomiting or defecation?” is yes, and the patient also says yes to the question “Do you suffer from abdominal discomfort for more than 30 minutes in the restroom or bed?” or “Do you feel restless due to that abdominal discomfort?” then the patient has confirmed abdominal distension. Answering yes to the other questions does not indicate abdominal distention, or only answering yes to questions 7 and 8 alone without question 4.1

The team also conducted analyses using clinical characteristics, blood, and imaging before and after an oral food challenge to investigate the pathophysiology.1

Among 14 patients who underwent an oral food challenge, 7 showed positive results. The latency period was 1.5 hours, and the most common symptoms included abdominal distension (100%), abdominal pain (71.4%), and nausea (71.4%). Patients received treatment with intravenous extracellular fluid infusion and ondansetron, resulting in reduced symptom duration.1

Investigators identified no specific serological markers of FPIES using the blood test data. However, the image analysis with computed tomography showed significant dilation and edema of the small intestine during the FPIES event, indicating that the dilation of the small intestine is linked to adult FPIE.1

“This study suggests that the small intestine should be a key focus for tissue analysis in future research to better understand the pathogenesis of FPIES,” investigators concluded.1

References

1. Watanabe S, Sato A, Shibuya K, et al. Small Intestinal Dilation Is Associated with Severe Abdominal Symptoms of Food-Protein-Induced Enterocolitis Syndrome in Adults. Allergy. Published online September 29, 2025. doi:10.1111/all.70081

2. Watanabe S, Sato A, Uga M, et al. A detailed intake-status profiling of seafoods in adult food-protein-induced enterocolitis syndrome patients. Allergol Int. 2024;73(2):275-281. doi:10.1016/j.alit.2023.12.003