Non-coeliac gluten sensitivity means gut symptoms such as bloating, pain and changed bowel habits, often with tiredness, headaches or a foggy head, that follow bread, pasta and other wheat-based foods in someone who has neither coeliac disease nor a wheat allergy. Many researchers prefer the name non-coeliac wheat sensitivity, because the trigger has not been pinned to gluten itself, and most people know the condition simply as gluten intolerance. No test can confirm it, and blinded feeding trials suggest that for most affected people the trigger is not gluten itself but other parts of wheat, fructans above all. Before any of that becomes relevant, coeliac disease has to be ruled out, with a blood test taken while wheat is still being eaten. This guide covers that first step, what the feeding trials found, what else in wheat can cause symptoms, and what testing can and cannot show.
A wheat allergy is a different condition, and it can be an emergency. Call 999 if eating brings on swelling of the lips, tongue or throat, difficulty breathing or wheezing, widespread hives, or sudden faintness or drowsiness. Wheat allergy runs through the fast-acting IgE side of the immune system, it can start within minutes, and it is assessed by a GP and an allergy clinic, never with a home test, ours included. If a reaction to wheat has ever involved any of those signs, settle how a food allergy differs from a food intolerance with your GP before investigating anything else.
Why should you test for coeliac disease first, while still eating gluten?
Coeliac disease is an autoimmune condition in which gluten makes the immune system attack the lining of the small intestine. A 2018 pooled analysis of studies covering more than 275,000 people puts it at around 1 in 100 people, and untreated it keeps damaging the gut lining however mild the symptoms feel. Its everyday symptoms, bloating, loose stools, tiredness and brain fog, overlap almost completely with wheat sensitivity, so nothing about how you feel can separate the two.
The overlap catches real people. In a UK population study that screened 1,002 adults, 13 in every 100 reported a sensitivity to gluten. When 200 people with self-reported gluten sensitivity were then investigated at a specialist clinic, 7 in every 100 of them, around 1 in 14, turned out to have coeliac disease. Without the clinic visit, their coeliac disease would have gone untreated.
Testing starts with a blood test for coeliac antibodies, arranged by your GP. The British Society of Gastroenterology guideline sets that test as the first step whenever coeliac disease is possible, and the antibodies it looks for fade once gluten leaves the diet, so the test has to happen while you are still eating gluten normally. NHS advice is to keep gluten in more than one meal every day for at least six weeks beforehand. Going gluten-free first can turn the test falsely negative and leave the diagnosis missed, and a missed diagnosis reaches beyond you, because close relatives of someone with coeliac disease are usually offered testing too.
What is non-coeliac gluten or wheat sensitivity?
Once coeliac disease and wheat allergy are excluded, symptoms that keep following wheat have a name. Researchers named it non-coeliac gluten sensitivity when gluten was assumed to be the trigger, and the shift towards non-coeliac wheat sensitivity in the research literature reflects blinded trials that cast doubt on gluten while leaving wheat itself under suspicion. A 2025 review describes gut symptoms accompanied by brain fog, headaches and fatigue, no damage to the gut lining, and no laboratory marker that can identify who has it. It sits among the more contested types of food intolerance, because unlike lactose intolerance there is no missing enzyme to point to.
Self-reporting runs far ahead of what blinded testing confirms. In a 2026 survey of 4,002 adults in the UK and USA, about 1 in 7 reported a sensitivity to gluten. Because no marker exists, the research community's agreed approach, the Salerno criteria, defines the condition by what symptoms do, improvement on a gluten-free diet and a return of symptoms when gluten is reintroduced without the person knowing which week contains it. Under those blinded conditions, most people who believe gluten is their problem do not react to it.
The everyday side of living without gluten, which foods contain it and how UK gluten-free labelling works, sits in our gluten intolerance guide.
Is gluten sensitivity real? What blinded trials show
The condition earned its place in the research literature through a 2011 Australian trial. 34 people with IBS whose symptoms were controlled on a gluten-free diet, and in whom coeliac disease had been excluded, ate bread and muffins containing either gluten or nothing added for up to six weeks, without knowing which. Those eating gluten reported more pain, bloating and tiredness within the first week. Nothing changed in their blood tests or inflammation markers, so the trial showed a real effect while finding no mechanism behind it.
The same research group then tightened the experiment. In a 2013 follow-up, 37 people with self-reported gluten sensitivity first spent two weeks on a diet low in FODMAPs, the fermentable carbohydrates that wheat carries alongside its proteins. Symptoms improved across the group. When gluten was then added back in disguise, it caused no more symptoms than the whey protein used as a comparison, and effects specific to gluten appeared in only 8 in every 100 participants.
A 2018 Norwegian trial put the two suspects head to head. 59 adults who had put themselves on a gluten-free diet ate muesli bars containing gluten, fructans or neither, a week of each in random order. The fructan bars caused the most bloating, and the gluten bars scored no worse than the placebo. Wheat is one of the biggest everyday sources of fructans, and how FODMAPs cause symptoms is well worked out, so for many people the fibre explains what the protein was blamed for.
Gluten has not been cleared entirely. In a 2015 Italian trial, 61 adults swallowed capsules containing a small daily amount of gluten or a rice-starch placebo for a week each, and reported more bloating, pain and foggy thinking during the gluten week. A 2017 pooled analysis of ten blinded trials covering 1,312 adults found symptoms specific to gluten in around 16 in every 100 participants. A minority do react to gluten itself. For most people carrying this label, the trigger is something else.
Could fructans cause wheat sensitivity symptoms?
Fructans lead the list, on the strength of the feeding trials, although responses vary from person to person and those trials do not show that gluten is never responsible. Wheat also carries a family of proteins called amylase trypsin inhibitors, which protect the growing grain from insects. In laboratory and animal studies, these proteins activated immune cells in the gut lining and worsened existing gut inflammation in mice, and modern bread wheat carried far more of them than older varieties such as emmer and einkorn. None of this has been demonstrated in people eating ordinary meals, so it remains a lead under investigation rather than an explanation.
The 2025 review weighs all three candidates, fructans, amylase trypsin inhibitors and gluten, and concludes that non-coeliac wheat sensitivity is probably not one condition. Different people appear to react to different components of the same foods, some mainly through fermentation, a few through the immune system, and that mix is part of why no single test for it exists.
Can the nocebo effect influence gluten sensitivity?
The 2017 pooled analysis also found that roughly 40 in every 100 participants reacted as strongly to the placebo as to gluten, a nocebo response, where expecting a reaction helps produce one. A 2024 trial run in Leeds and the Netherlands tested expectation directly. 83 people with self-reported gluten sensitivity ate the same oat bread across a test day and were told, truthfully or not, whether it contained gluten. The group who believed they were eating gluten and actually were reported the most symptoms, and believing it without eating it produced scores the trial could not tell apart from eating it unknowingly.
None of that means the symptoms are imagined. The gut and the brain signal to each other constantly, expectation can amplify real gut sensations, and the trial's own researchers point to that gut-brain interaction rather than to invention. What it changes is the method. An open experiment, cutting wheat out and watching what happens, cannot separate the food from the expectation, so improvement on its own proves very little. Reintroduction, ideally without knowing which week contains the suspect food, is the part that carries the weight.
How is non-coeliac gluten sensitivity diagnosed?
No blood test, breath test or biopsy can identify it, on the NHS or anywhere else. Identification is a sequence. Coeliac disease is tested first, while gluten is still being eaten. A possible wheat allergy goes to a GP wherever a reaction has been rapid or has involved skin or breathing. After both, the recognised approach is a time-limited spell without wheat, planned with a registered dietitian or our clinical team, followed by deliberate reintroduction to check whether symptoms actually track the food. The Salerno criteria formalise the same logic for research, with symptom scoring and a blinded rechallenge, and the 2025 review notes that the full protocol is rarely practical in routine care, which is why the guided version is what happens in clinics.
Open-ended restriction without support is the pattern to avoid. Wheat is a staple that carries fibre and fortified nutrients, gluten-free substitutes tend to cost more, and dropping a staple for months on a hunch narrows a diet for no confirmed gain. Improvement while avoiding wheat means little until the food comes back and the symptoms return with it. Anyone with a history of restrictive or disordered eating should involve their GP or a registered dietitian before removing any staple food group.
Can a food intolerance test detect non-coeliac gluten sensitivity?
No. The condition has no defining antibody or marker, so no consumer test can identify it, ours included. Our test also cannot diagnose coeliac disease. Coeliac testing is a specific NHS blood test arranged through your GP, and it happens before any test bought at home.
What our IgG test for food sensitivities measures is different, and it is more specific than a single wheat result. The panel analyses IgG antibodies against 270 foods and drinks, and its cereals section separates the grains that most pages lump together. Wheat, gliadin (one of the proteins that make up gluten), wheat bran, durum wheat, spelt, emmer and einkorn are each tested in their own right, alongside rye, barley and malt. An elevated result may indicate a food sensitivity to that specific grain. Once coeliac disease has been ruled out, that resolution matters, because wheat is not one question. Results raised against modern bread wheat but not spelt or rye set up a different reintroduction plan from results raised across every grain on the list.
Researchers have also studied IgG antibodies against gliadin as a possible marker of the condition itself, and the findings so far conflict, as the 2025 review sets out. So a raised IgG result is a starting shortlist for a guided elimination and reintroduction, not a diagnosis of wheat sensitivity, and our clinical team reads cereal results with exactly those limits in mind.
When should you see a GP about gluten or wheat symptoms?
See your GP before changing your diet if you have never been tested for coeliac disease, and keep eating gluten until that test is done. Book an appointment whatever your plans if you have blood in your stool, unexplained weight loss, a change in bowel habit lasting more than three weeks, difficulty swallowing, persistent vomiting, the constant tiredness or breathlessness of iron-deficiency anaemia, new gut symptoms over the age of 50, or a family history of bowel or ovarian cancer. Mouth ulcers that keep returning, unexplained anaemia and a close relative with coeliac disease are each reasons to ask your GP specifically about coeliac testing. Any reaction involving swelling, difficulty breathing or widespread hives is a 999 call at the time it happens and an allergy question for your GP afterwards, never a home experiment.
This guide is for information only and does not replace medical advice. Speak to your GP or pharmacist about your own symptoms.
Sources
- Singh P, Arora A, Strand TA, et al. (2018). Global Prevalence of Celiac Disease: Systematic Review and Meta-analysis. Clinical Gastroenterology and Hepatology. PubMed | DOI
- Aziz I, Lewis NR, Hadjivassiliou M, et al. (2014). A UK study assessing the population prevalence of self-reported gluten sensitivity and referral characteristics to secondary care. European Journal of Gastroenterology & Hepatology. PubMed | DOI
- Ludvigsson JF, Bai JC, Biagi F, et al. (2014). Diagnosis and management of adult coeliac disease: guidelines from the British Society of Gastroenterology. Gut. PubMed | DOI
- Maimaris S, Scarcella C, Memoli GA, et al. (2025). Non-Coeliac Wheat Sensitivity: Symptoms in Search of a Mechanism, or a Distinct Well-Defined Clinical Entity? A Narrative Review. International Journal of Molecular Sciences. PubMed | DOI
- Shiha MG, Sanders DS, Burton-Murray H, et al. (2026). Prevalence of Self-Reported Non-Coeliac Gluten Sensitivity and Its Association With Disorders of Gut-Brain Interaction and Disordered Eating. United European Gastroenterology Journal. PubMed | DOI
- Catassi C, Elli L, Bonaz B, et al. (2015). Diagnosis of Non-Celiac Gluten Sensitivity (NCGS): The Salerno Experts' Criteria. Nutrients. PubMed | DOI
- Biesiekierski JR, Newnham ED, Irving PM, et al. (2011). Gluten causes gastrointestinal symptoms in subjects without celiac disease: a double-blind randomized placebo-controlled trial. The American Journal of Gastroenterology. PubMed | DOI
- Biesiekierski JR, Peters SL, Newnham ED, et al. (2013). No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates. Gastroenterology. PubMed | DOI
- Skodje GI, Sarna VK, Minelle IH, et al. (2018). Fructan, Rather Than Gluten, Induces Symptoms in Patients With Self-Reported Non-Celiac Gluten Sensitivity. Gastroenterology. PubMed | DOI
- Di Sabatino A, Volta U, Salvatore C, et al. (2015). Small Amounts of Gluten in Subjects With Suspected Nonceliac Gluten Sensitivity: A Randomized, Double-Blind, Placebo-Controlled, Cross-Over Trial. Clinical Gastroenterology and Hepatology. PubMed | DOI
- Molina-Infante J, Carroccio A (2017). Suspected Nonceliac Gluten Sensitivity Confirmed in Few Patients After Gluten Challenge in Double-Blind, Placebo-Controlled Trials. Clinical Gastroenterology and Hepatology. PubMed | DOI
- de Graaf MCG, Lawton CL, Croden F, et al. (2024). The effect of expectancy versus actual gluten intake on gastrointestinal and extra-intestinal symptoms in non-coeliac gluten sensitivity: a randomised, double-blind, placebo-controlled, international, multicentre study. The Lancet Gastroenterology & Hepatology. PubMed | DOI
- Zevallos VF, Raker V, Tenzer S, et al. (2017). Nutritional Wheat Amylase-Trypsin Inhibitors Promote Intestinal Inflammation via Activation of Myeloid Cells. Gastroenterology. PubMed | DOI
- NHS. Coeliac disease. nhs.uk
