Celiac disease, wheat allergy, and nonceliac gluten and wheat sensitivity are distinct gluten- and wheat-related disorders that share overlapping symptoms but require different diagnostic and management strategies (Table 1).1 A systematic evaluation is essential to differentiate among them and guide appropriate care across clinical settings (Figure 1).
Distinguishing among gluten-related disorders
Evaluation of gluten- and wheat-related symptoms.
aConsider low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet, particularly if gastrointestinal symptoms persist.
bIdeally, challenge is blinded to mitigate nocebo effect.
Ig = immunoglobulin; tTG-IgA = tissue transglutaminase immunoglobulin A
GLUTEN-RELATED DISORDERS: AN OVERVIEW
Celiac disease
Celiac disease is an autoimmune enteropathy driven by gluten in genetically susceptible individuals (most often positive for human leukocyte antigen [HLA]-DQ2 or -DQ8 haplotype). Symptoms include diarrhea, bloating, weight loss, iron-deficiency anemia, and extraintestinal manifestations such as fatigue and osteoporosis.
While clinical symptoms alone may be convincing, diagnosis of celiac disease requires formal testing for confirmation, the results of which may have serious long-term implications for management, screening, and health maintenance.2 Diagnosis requires positive serology and confirmatory duodenal biopsy showing villous atrophy while the patient is consuming gluten.2 The preferred screen is tissue transglutaminase (tTG) immunoglobulin (Ig) A antibody testing (tTG-IgA), with total IgA checked to rule out deficiency; for patients with low total IgA, tTG-IgG or deamidated gliadin peptide IgG levels should be used.2
Biopsy remains the standard in adults, with multiple samples taken from both the distal duodenum and duodenal bulb to detect patchy disease. Histology typically shows intraepithelial lymphocytosis, crypt hyperplasia, and villous blunting or atrophy.1,2
Definitive management involves lifelong strict adherence to a gluten-free diet.2
Wheat allergy
This immunologically mediated hypersensitivity to wheat proteins can be IgE-mediated (well-characterized; this form is the primary focus of this article), non– IgE-mediated, or mixed (more nebulous). The immune response typically involves mast-cell activation and may be triggered by ingestion, inhalation, or skin contact. Clinical manifestations are diverse and may include cutaneous (eg, urticaria, angioedema, atopic dermatitis), respiratory (asthma, rhinitis), cardiovascular (hypotension, syncope, presyncope), and gastrointestinal symptoms (abdominal pain, vomiting, diarrhea). This list of symptoms is representative but not exhaustive. Severe reactions such as anaphylaxis can occur, particularly in the IgE-mediated form.1
Diagnosis is based on clinical history, skin-prick testing, serum wheat IgE level, and, when necessary, a supervised oral food challenge, which remains the gold standard.
Management requires strict avoidance of wheat; patients with a history of anaphylaxis should carry self-injectable epinephrine. Most children outgrow wheat allergy, though persistence into adulthood can occur.1
Nonceliac gluten and wheat sensitivity
This condition is defined by the development of gastrointestinal, extraintestinal symptoms, or both in response to gluten or wheat ingestion in individuals without celiac disease or wheat allergy. Representative symptoms may include bloating, fatigue, headache, numbness, tingling, neuropathy, dizziness, syncope, and even altered mentation, or “brain fog.”
Diagnosis is by exclusion. A structured trial of a gluten-free diet with symptom improvement followed by a gluten rechallenge (Salerno criteria3,4) with symptom exacerbation can help confirm the diagnosis.5 This dietary trial is ideally blinded to mitigate the nocebo effect (see below), or anticipated negative reactions.5 In addition to the practical limitations of the Salerno criteria, they may not adequately distinguish non-celiac gluten and wheat sensitivity from functional gastrointestinal disorders with overlapping symptoms. Although there is a search for validated biomarkers in this condition, none are currently identified.3
Management typically involves dietary modification limiting gluten or wheat with attention to nutritional adequacy.
NOT ALL GLUTEN COMES FROM WHEAT
Here is a key point: wheat refers to the cereal grain from the genus Triticum, which is a staple food worldwide and the primary source of flour for bread, pasta, and many other foods. Wheat contains multiple protein fractions, including albumins, globulins, and most notably, gluten proteins. In contrast, gluten is a specific composite of storage proteins—primarily gliadins and glutenins—found in wheat and other grains. Proteins in related grains such as barley (hordeins) and rye (secalins) also provoke an immune response. All wheat contains gluten, but not all gluten comes from wheat.1
WHEN TO REFER
Referral to gastroenterology is appropriate for all patients with celiac disease, particularly for access to an expert dietitian who is knowledgeable about the gluten-free diet. Referral is also useful when celiac serologies and biopsy results are discordant, if there is concern for alternative enteropathies such as eosinophilic enteritis or Crohn disease, or if symptoms persist despite dietary intervention.
Referral to allergy and immunology is recommended in patients with suspected IgE-mediated reactions, such as rapid-onset urticaria, respiratory symptoms, or anaphylaxis after wheat ingestion, and in cases where clarification of sensitization profiles is needed through testing or supervised oral food challenge.
MECHANISTIC COMPLEXITY AND CLINICAL CONFUSION
Not just gluten
While gluten is often presumed to be the culprit in patients with nonceliac gluten sensitivity, mounting evidence suggests that other components of wheat and related grains may be responsible for symptoms in a subset of patients. One of the leading culprits is fructan, a type of fermentable oligosaccharide categorized under the broader FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) group.6 Fructans (Table 2) are poorly absorbed in the small intestine and rapidly fermented by colonic bacteria, producing gas and drawing water into the bowel, which can result in bloating, flatulence, and diarrhea—symptoms commonly attributed to gluten. Notably, research has shown that some patients with self-reported gluten sensitivity experience symptom recurrence in response to fructans, not gluten, when evaluated in blinded trials.7
Common dietary sources of fructans
Another class of compounds implicated in gluten- and wheat-related symptoms is amylase-trypsin inhibitors, which are nongluten proteins found in wheat. Animal-model studies suggest they may activate toll-like receptor 4, stimulating innate immune responses in the gut and potentially contributing to symptoms such as abdominal discomfort, fatigue, and low-grade inflammation.8 Amylase-trypsin inhibitors are resistant to digestion and are present in higher concentrations in modern wheat strains, raising questions about their role in the rising prevalence of gluten-related complaints.
Symptom overlap
The gastrointestinal symptoms of nonceliac gluten sensitivity can overlap with irritable bowel syndrome, a condition characterized by chronic (> 6 months) abdominal pain and bowel symptoms. A diet low in FODMAPs is beneficial in patients with irritable bowel syndrome. If a patient with nonceliac gluten sensitivity does not improve with a gluten- or wheat-limited diet, a low-FODMAP diet may offer diagnostic and therapeutic clarity.
The nocebo effect
Clinicians should also consider the nocebo effect, where a patient’s negative expectations about gluten may amplify symptoms even in the absence of a true physiologic reaction during management of nonceliac gluten sensitivity. Physicians and dietitians should educate patients that the benefits they attribute to “gluten-free” eating may, in fact, reflect a reduction in nongluten wheat compounds or overall processed carbohydrate load.6,7,9 Collaborative care with a dietitian can help personalize dietary trials, avoid unnecessary restrictions, and better identify triggers responsible for symptoms.
TAKE-HOME POINTS
Celiac disease is an autoimmune enteropathy that is diagnosed based on positive serology (high tTG-IgA level with normal total IgA) and duodenal biopsy (villous atrophy) while the patient is consuming gluten. Management is a lifelong strict gluten-free diet.
Wheat allergy is an IgE-mediated hypersensitivity reaction with rapid onset involving the cutaneous, respiratory, gastrointestinal, and cardiovascular systems. Diagnosis is based on wheat-specific IgE testing with food challenge or without food challenge if there is previous evidence from skin-prick testing or wheat-specific IgE levels.
Nonceliac gluten and wheat sensitivity is a diagnosis of exclusion when celiac disease and wheat allergy are ruled out; symptoms (bloating, fatigue, “brain fog”) improve with gluten or wheat withdrawal and recur on rechallenge. There are no validated biomarkers for nonceliac gluten and wheat sensitivity at this time.
Beyond gluten, other wheat components (fructans, amylase-trypsin inhibitors) and overlapping functional disorders (like irritable bowel syndrome) may drive symptoms. Consider low-FODMAP diet trials and collaborate with dietitians to avoid unnecessary restrictions.
DISCLOSURES
Dr. Jansson-Knodell has disclosed ownership interest (stock, publicly traded) in Exact Sciences Corporation, Johnson & Johnson, Medtronic, Pfizer, and United Healthcare. The other authors report no relevant financial relationships which, in the context of their contributions, could be perceived as a potential conflict of interest.
- Copyright © 2026 The Cleveland Clinic Foundation. All Rights Reserved.
REFERENCES
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