Eosinophilic Gastroenteritis: Food Allergy Triggers, Elimination Diet & Dupilumab Guide

What Is Eosinophilic Gastroenteritis?

Eosinophilic gastroenteritis (EGE) is a rare but increasingly recognized chronic inflammatory condition characterized by abnormal accumulation of eosinophils — white blood cells normally involved in parasite defense and allergic response — within the walls of the stomach, small intestine, and sometimes the colon. Unlike its more well-known cousin eosinophilic esophagitis (EoE), which is confined to the esophagus, EGE represents a broader spectrum of gastrointestinal eosinophilic infiltration that can affect multiple gut segments simultaneously and presents with a wider, more variable set of symptoms.

First described by Kaijser in 1937, EGE remains a diagnosis that eludes many clinicians for months or years because its presentation overlaps with irritable bowel syndrome, Crohn's disease, food intolerance, and celiac disease. The estimated prevalence is 1 to 30 per 100,000 people, though this figure is widely thought to underestimate true burden given the requirement for biopsy-based diagnosis.

The Three Anatomical Layers of EGE

Klein's 1970 classification, still clinically useful today, stratifies EGE by the depth of eosinophil infiltration into the gut wall:

• Mucosal layer involvement (most common, ~57% of cases): Presents with nausea, vomiting, abdominal pain, diarrhea, and protein-losing enteropathy or malabsorption. Weight loss and iron deficiency anemia are common.
• Muscular layer involvement (~30% of cases): Eosinophil infiltration of the muscularis propria causes wall thickening and dysmotility. Patients present with obstructive symptoms — postprandial bloating, nausea, and in severe cases, gastric outlet or small bowel obstruction.
• Subserosal layer involvement (least common, ~13%): Associated with ascites (eosinophil-rich peritoneal fluid), which paradoxically may be the most diagnostically clear-cut presentation. Peripheral blood eosinophilia is typically pronounced.

The layer of involvement significantly impacts the diagnostic approach. Mucosal disease is accessible via standard upper endoscopy with biopsy; muscular disease may require full-thickness surgical biopsy; subserosal disease may be detected through ascitic fluid analysis showing eosinophilia.

EGE vs. Eosinophilic Esophagitis: A Critical Distinction

EoE and EGE share an underlying allergen-driven, Th2-skewed immune mechanism, but they diverge in important clinical ways. EoE is diagnosed when eosinophil counts exceed 15 eos/HPF in the esophagus (which normally contains no eosinophils) in the context of dysphagia or food impaction. EGE applies when eosinophilia is found in the stomach or intestines — tissues that normally do contain some eosinophils, which is precisely why the diagnostic threshold is higher and more contested.

Symptom profiles also diverge. While EoE primarily causes dysphagia and food impaction in adults, EGE manifests as nausea, cramping abdominal pain, diarrhea, malabsorption, protein-losing enteropathy, and ascites. The esophagus is typically spared in pure EGE, though overlap syndromes (involving both esophagus and stomach or intestine) do occur and are increasingly documented.

Food Allergy Triggers and the Immune Mechanism

The current mechanistic understanding of EGE frames it as an aberrant type 2 immune response driven primarily by food antigens, though environmental allergens and sometimes no identifiable trigger contribute. The cascade begins when dietary proteins — especially from common allergenic foods — are presented to T helper 2 (Th2) cells in genetically susceptible individuals.

The Th2 Cytokine Cascade

Allergen exposure triggers Th2 cells to release interleukin-4 (IL-4), IL-5, IL-13, and thymic stromal lymphopoietin (TSLP). Of these, IL-5 is the primary eosinophil survival and activation factor — it stimulates bone marrow eosinophil production, promotes their differentiation, and prolongs their survival in inflamed tissue. IL-4 and IL-13 drive IgE class switching in B cells and promote mucus production and epithelial barrier dysfunction. IL-13 also has direct effects on epithelial permeability, allowing more allergen penetration in a self-reinforcing cycle.

Eotaxins — particularly eotaxin-1 (CCL11) and eotaxin-3 (CCL26) — serve as chemotactic signals that pull circulating eosinophils into the gut tissue. In EGE patients, both eotaxin expression and tissue eosinophil counts correlate with disease activity, making them potential biomarkers for monitoring treatment response.

The Six Most Common Dietary Triggers

Food allergy skin prick testing and specific IgE measurements perform poorly in EGE, with false-negative rates that make them unreliable as standalone diagnostic tools. Empiric elimination based on the most common triggers remains the most clinically validated approach. The six food groups implicated most frequently are:

1. Cow's milk (dairy) — The single most common trigger across eosinophilic GI disorders, implicated in up to 50–75% of cases. Casein proteins are the primary sensitizing antigens.
2. Wheat — The second most frequent. Distinct from celiac disease; the mechanism is non-IgE-mediated type 2 inflammation rather than gliadin-specific autoimmunity.
3. Eggs — Particularly egg white proteins (ovalbumin, ovomucoid). Common co-sensitization with milk is seen in pediatric cases.
4. Soy — Legume family proteins. Soy-milk substitutes are not safe for soy-sensitized patients.
5. Peanuts and tree nuts — Often co-sensitized; clinical practice usually eliminates all nuts as a class.
6. Seafood (fish and shellfish) — Fish and shellfish are structurally distinct allergens but both implicated; they are typically eliminated together.

Beyond these six, sesame has emerged as an important trigger and is now the ninth major allergen recognized by the FDA. Some patients with severe or refractory EGE have additional triggers outside these categories, which is why elemental diets — bypassing all food protein entirely — achieve the highest remission rates.

Is EGE Always Allergy-Driven?

Not all EGE is food-allergen-mediated. A subset of patients shows no identifiable dietary trigger, normal IgE levels, and eosinophilic infiltration that may be driven by innate immune activation, gut microbiome dysbiosis, or non-IgE-mediated pathways. These patients often respond poorly to dietary elimination alone and require pharmacological management. Differentiating allergic from non-allergic EGE has therapeutic implications: allergic EGE is best treated dietarily; non-allergic or mixed EGE may require systemic or biologic therapy from the outset.

Biopsy Diagnosis: The >20 Eos/HPF Standard

Diagnosing EGE requires a systematic approach combining clinical assessment, laboratory evaluation, endoscopic examination, and histopathological analysis. No single test is sufficient; the diagnosis is made by integrating multiple data points and excluding alternative causes of eosinophilia.

Step 1: Clinical Suspicion and Lab Workup

The first step is ruling out the most common secondary causes of GI eosinophilia. Before attributing eosinophilic infiltration to a primary EGE diagnosis, clinicians must exclude:

• Parasitic infections: Strongyloides, Toxocara, Anisakis, and other helminths can cause significant tissue eosinophilia. Stool ova and parasite examination, Strongyloides serology, and relevant travel history are essential.
• Drug-induced eosinophilia: NSAIDs, clofazimine, carbamazepine, and certain antibiotics can cause GI eosinophilia. A thorough medication review is critical.
• Hypereosinophilic syndrome (HES): When peripheral blood eosinophilia exceeds 1,500 cells/μL for more than six months with end-organ damage, HES must be excluded.
• Inflammatory bowel disease: Crohn's disease can cause secondary eosinophilic infiltration that mimics primary EGE.
• Connective tissue disorders: Systemic sclerosis and polyarteritis nodosa occasionally present with GI eosinophilia.

Laboratory findings in EGE commonly include peripheral blood eosinophilia (present in ~70–80% of cases), elevated total IgE, hypoalbuminemia (in cases with protein-losing enteropathy), and iron deficiency anemia. A normal peripheral eosinophil count does not exclude EGE.

Step 2: Endoscopy and the Biopsy Protocol

Upper endoscopy with biopsy is the cornerstone of EGE diagnosis. However, because EGE involvement can be patchy and non-uniform, a systematic biopsy protocol significantly improves diagnostic yield:

• Obtain at least 4–6 biopsies from multiple sites in the stomach (antrum and body) and duodenum (bulb and second portion).
• If colonoscopy is performed, biopsy the terminal ileum and multiple colonic segments.
• Endoscopic appearance may be normal, show erythema, mucosal edema, polyps, ulcerations, or nodularity — none of these are pathognomonic.
• Capsule endoscopy or deep enteroscopy may be required when disease is suspected in the mid-small bowel beyond endoscopic reach.

Step 3: Imaging and Ancillary Studies

CT enterography or MRI enterography can reveal wall thickening, mesenteric lymphadenopathy, and ascites, particularly in muscular or subserosal EGE. Ascitic fluid analysis showing >10% eosinophils is essentially pathognomonic for subserosal EGE. Small bowel follow-through may demonstrate mucosal fold thickening or strictures. These imaging modalities complement endoscopy rather than replace it.

Dietary Therapies: Elemental Diet and the 6-Food Elimination Protocol

Dietary therapy is the cornerstone of management for food-allergen-driven EGE, mirroring its established role in EoE. The principle is straightforward: remove the antigenic food proteins driving Th2-mediated eosinophil recruitment, allow the gut mucosa to heal, then systematically reintroduce foods to identify individual triggers. The approach ranges from the most restrictive (elemental diet) to the targeted empiric elimination of the six most common culprit groups.

Elemental (Amino Acid-Based) Diet

The elemental diet replaces all intact dietary protein with free amino acids — the building blocks of protein that carry no allergenic properties because there are no intact peptide sequences to trigger an immune response. Studies in both pediatric and adult EoE report remission rates approaching 90% with elemental formula, the highest of any dietary intervention. By extrapolation and small case series, similar efficacy is expected in EGE, though large controlled trials in EGE specifically are lacking.

The practical limitations of elemental diets are significant. The formulas are typically unpalatable, expensive, and may require nasogastric tube administration in patients unable to consume adequate volumes orally. Long-term adherence is poor in adults. For these reasons, elemental diet is typically used as a diagnostic tool (to confirm dietary contribution to disease activity), as a bridge to remission in severe cases, or in refractory patients who fail empiric elimination.

The 6-Food Elimination Diet (6-FED)

The 6-FED removes all products containing milk, wheat, eggs, soy, peanuts/tree nuts, and fish/shellfish simultaneously. In EoE, the 6-FED achieves histological remission (defined as <15 eos/HPF) in approximately 50–72% of patients depending on the study. When remission is achieved, foods are reintroduced one group at a time over a structured timeline, with endoscopic surveillance after each reintroduction to identify the specific trigger(s). This approach can ultimately identify the individual culprit food(s) in many patients, allowing a less restrictive long-term diet targeted only to confirmed triggers.

The 6-FED is challenging to implement. Dairy and wheat are pervasive in Western diets, requiring careful label reading, dietary counseling, and often specialist support from a registered dietitian experienced in elimination protocols. Cross-contamination in food preparation is a significant concern.

Step-Up Elimination Approaches

Recognizing the burden of 6-FED, researchers have explored step-up strategies starting with fewer eliminated foods:

• 1-food elimination (dairy only): Targets the most common single trigger. Remission rates in EoE are approximately 30–40%. Appropriate for motivated patients willing to escalate if insufficient.
• 2-food elimination (dairy + wheat): Targets the two most common triggers. Achieves remission in ~40–50% of EoE patients.
• 4-food elimination: Removes dairy, wheat, eggs, and legumes (soy/peanut). Remission rates approach 50–60%.
• 6-food elimination: Maximum empiric dietary restriction, highest remission rate outside elemental diet.

Nutritional Monitoring During Elimination

Extended elimination of dairy (calcium, vitamin D, B12), wheat (B vitamins, fiber), and eggs (protein, B12, folate) creates meaningful nutritional risk. Baseline and monitoring labs should include: complete blood count, iron studies, B12, folate, 25-OH vitamin D, calcium, albumin, and zinc. Supplementation guided by lab findings — not just guesswork — is appropriate throughout the elimination period.

Dupilumab and Emerging Biologic Therapies

The landscape of EGE treatment changed meaningfully in 2022 when the FDA approved dupilumab (Dupixent) for eosinophilic esophagitis — marking the first biologic approval for any eosinophilic GI disorder. This approval, built on two pivotal randomized controlled trials (TREET-1 and TREET-2), demonstrated that blocking the IL-4/IL-13 signaling axis with dupilumab produced sustained histological and symptomatic remission in EoE. The implications for EGE are significant.

How Dupilumab Works

Dupilumab is a fully human monoclonal antibody that blocks the shared receptor subunit (IL-4Rα) used by both IL-4 and IL-13. By antagonizing this receptor, dupilumab simultaneously blocks both cytokines — which are the central drivers of the Th2 cascade underlying eosinophilic GI inflammation. The result is reduced eosinophil recruitment, normalized epithelial barrier function, and reduced mucosal inflammation across eosinophilic disorders including atopic dermatitis, asthma, chronic rhinosinusitis, and EoE. Given that EGE shares the identical Th2 pathophysiology, dupilumab represents a mechanistically rational treatment.

Clinical Evidence in EGE

While EGE-specific Phase 3 trial data for dupilumab is not yet available as of mid-2026, several lines of evidence support its utility:

• Case series and retrospective cohorts report histological improvement in eosinophilic gastritis and gastroenteritis with dupilumab, mirroring EoE findings.
• A Phase 2 randomized controlled trial examining dupilumab in eosinophilic gastritis and/or duodenitis (EGID) showed significantly reduced eosinophil counts and symptom burden vs. placebo.
• Patients with concurrent EoE and EGE who received dupilumab for their esophageal disease have shown concomitant improvement in gastric and intestinal biopsy findings.

Sanofi and Regeneron have ongoing trials specifically for eosinophilic gastritis and duodenitis with dupilumab, and FDA approval for these indications is anticipated in the near term.

Other Biologics in the Pipeline

The biologic pipeline for EGE extends beyond dupilumab. Several agents targeting different nodes of the eosinophil recruitment pathway are in active development:

• Benralizumab (Fasenra): Anti-IL-5Rα monoclonal antibody that depletes eosinophils through antibody-dependent cellular cytotoxicity. Currently in Phase 2 trials for EoE and EGE.
• Mepolizumab (Nucala) and reslizumab (Cinqair): Anti-IL-5 antibodies that reduce eosinophil survival. Early data in EGE shows eosinophil reduction but symptom outcomes have been mixed.
• Cendakimab (RVT-1502): An oral IL-13 receptor antagonist that has shown Phase 3 efficacy in EoE. Oral bioavailability makes it potentially more acceptable than injectable biologics for long-term use in EGE.
• Omalizumab (Xolair): Anti-IgE antibody. Limited evidence in EGE; may be useful in IgE-mediated subgroups.

Conventional Pharmacological Options

For patients not yet on or eligible for biologic therapy, conventional treatments include:

• Corticosteroids (prednisone, budesonide): Highly effective for acute flares, with remission rates exceeding 80–90%. However, long-term use is limited by systemic side effects. Budesonide capsules (targeting the small intestine) offer a partial steroid-sparing advantage through first-pass hepatic metabolism.
• Montelukast and cromolyn sodium: Mast cell stabilizers and leukotriene antagonists with modest evidence in EGE. Generally used as adjuncts or in mild disease.
• Azathioprine and 6-mercaptopurine: Steroid-sparing immunosuppressants used in refractory cases requiring long-term treatment. Require monitoring for bone marrow suppression and hepatotoxicity.

Treatment Comparison: Evidence Summary