Quick answer: Coeliac disease is an autoimmune condition in which gluten damages the lining of the small intestine; it affects around 1 in 100 people, can start at any age and needs lifelong strict gluten avoidance once confirmed. Non-coeliac gluten sensitivity describes gut or whole-body symptoms after eating wheat without coeliac disease or wheat allergy, and research suggests that in many people the trigger is actually fructans – fermentable carbohydrates in wheat – rather than gluten itself. The most important step is to get tested for coeliac disease while you are still eating gluten.
“I think I’m gluten intolerant” is one of the most common things people tell me in a first session. Often they have already cut bread and pasta and feel somewhat better – but they are not sure why, and they have never been tested. Gluten-related problems are real, but they are not all the same, and the difference matters. If bloating is your main symptom, it may also help to read why you are always bloated after eating.
What is the difference between gluten intolerance and coeliac disease?
There are three distinct conditions that often get grouped together:1
- Coeliac disease – an autoimmune condition. Gluten triggers an immune reaction that damages the small intestine lining, which can affect absorption of iron, folate, B12, calcium and other nutrients. It can be confirmed with blood tests and, in adults, usually an intestinal biopsy.
- Wheat allergy – an allergic reaction to wheat proteins, often appearing quickly, with symptoms such as hives, swelling, wheezing or digestive upset.
- Non-coeliac gluten (or wheat) sensitivity (NCGS) – symptoms after eating gluten-containing grains when coeliac disease and wheat allergy have been ruled out. There is no blood marker; it is defined by excluding the other two and by how symptoms respond.2
What are the symptoms of gluten intolerance in adults?
Coeliac disease and gluten sensitivity can look very similar. Symptoms commonly associated with both include:
- bloating, wind and abdominal pain
- diarrhoea, constipation or alternating bowel habits
- tiredness and brain fog
- headaches and joint aches
Coeliac disease can also show up with few gut symptoms at all – for example, as iron deficiency that does not respond to supplements, mouth ulcers, low bone density or raised liver enzymes. A meta-analysis found that around 3% of people with iron deficiency anaemia had biopsy-confirmed coeliac disease.5 You cannot tell the conditions apart from symptoms alone.
Can you develop gluten intolerance later in life?
Yes. Coeliac disease can begin at any age, including in older adults, and many people are found to have it in their 40s, 50s or later.1 Gluten sensitivity also tends to be reported in adults. A new reaction to bread or pasta in adulthood is a reason to get tested, not to assume it is “just” an intolerance.
Why should you test for coeliac disease before going gluten-free?
Coeliac blood tests (tissue transglutaminase IgA, together with total IgA) and the intestinal biopsy rely on your immune system actively reacting to gluten. If you have already cut gluten out, results can come back falsely normal.1 Your doctor may then ask you to eat gluten again for several weeks before testing, which many people find difficult.
Knowing whether you have coeliac disease changes everything: it requires lifelong, strict avoidance (including cross-contamination), follow-up of nutrient levels and bone health, and screening of close relatives. Gluten sensitivity usually allows much more flexibility.
When to see your doctor first
- Unintended weight loss or persistent diarrhoea
- Iron deficiency, low B12 or folate, or low bone density
- A close relative with coeliac disease, or type 1 diabetes or autoimmune thyroid disease
- Blood in the stool or symptoms that wake you at night
- Hives, swelling of the lips or throat, or wheezing after wheat (seek urgent care)
Is it really gluten – or the fructans in wheat?
This is where the research gets interesting. In a carefully controlled study, people with self-reported gluten sensitivity whose diets were already low in FODMAPs showed no specific reaction to gluten.3 In a later blinded trial, the same type of patients reacted more to fructans – fermentable carbohydrates found in wheat, rye, barley, onion and garlic – than to gluten.4
In practice, this means that many people who feel better without bread may be responding to less fructan rather than less gluten. That opens up more options: spelt sourdough, for example, or a structured low-FODMAP reintroduction can sometimes show that small amounts of gluten are fine, while large servings of wheat or onion are not.
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Book your free 15-minute call →How can nutritional therapy help with gluten-related symptoms?
- Making sure coeliac testing happens first, with your doctor, while you are still eating gluten.
- If coeliac disease is confirmed, supporting a nourishing, varied gluten-free diet and helping your medical team monitor iron, folate, B12, vitamin D and calcium.
- If coeliac disease is ruled out, using a structured elimination and reintroduction (with a symptom diary) to identify whether gluten, fructans or something else is the trigger – so you avoid only what you need to.
- Looking at the wider picture: SIBO, gut sensitivity, stress and the microbiome can all make wheat feel harder to digest.
Frequently asked questions
How do I know if I'm gluten intolerant or coeliac?
Only testing can tell. Ask your doctor for coeliac blood tests while you are still eating gluten. If they are negative and wheat allergy is unlikely, gluten sensitivity or a reaction to wheat fructans may be explored.
Can I test for coeliac disease if I've already stopped eating gluten?
Results may be falsely normal. Your doctor may advise reintroducing gluten for several weeks before testing. Do not do this without guidance if you have had severe reactions.
Is gluten intolerance real?
Yes, people with non-coeliac gluten sensitivity have real symptoms. Research suggests that in some of them the trigger is fructans in wheat rather than gluten, which can change which foods need to be limited.
Is sourdough bread OK for gluten sensitivity?
Traditional long-fermented sourdough is lower in fructans, and some people with wheat sensitivity tolerate it better. It still contains gluten and is not suitable for coeliac disease.
Is a gluten-free diet healthier?
Not automatically. Many gluten-free products are low in fibre and high in refined starch. A gluten-free diet is essential in coeliac disease, but if you do not need it, removing gluten without reason can reduce variety and fibre.
References
- Al-Toma A, et al. European Society for the Study of Coeliac Disease (ESsCD) guideline for coeliac disease and other gluten-related disorders. United European Gastroenterol J. 2019. PubMed: PMID 31210940
- Catassi C, et al. Diagnosis of non-celiac gluten sensitivity (NCGS): the Salerno experts' criteria. Nutrients. 2015. PubMed: PMID 26096570
- Biesiekierski JR, et al. No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates. Gastroenterology. 2013. PubMed: PMID 23648697
- Skodje GI, et al. Fructan, rather than gluten, induces symptoms in patients with self-reported non-celiac gluten sensitivity. Gastroenterology. 2018. PubMed: PMID 29102613
- Mahadev S, et al. Prevalence of celiac disease in patients with iron deficiency anemia – a systematic review with meta-analysis. Gastroenterology. 2018. PubMed: PMID 29689265
This article is for educational purposes and is not medical advice. Nutritional therapy does not replace medical care. Always work with your doctor for any persistent or new symptoms and before making changes to your care, medication or supplements.