If bread, pasta or other gluten-containing foods seem to make you feel unwell, it is understandable to wonder whether you are gluten intolerant.
But “gluten intolerance” is not a precise medical diagnosis.
Several different conditions can cause symptoms after eating foods that contain gluten or wheat. These include coeliac disease, wheat allergy and what is commonly called non-coeliac gluten sensitivity. They are not the same, and the right way to investigate them differs.
That distinction matters because starting a strict gluten-free diet before being tested for coeliac disease can make the tests inaccurate.
So, if you think gluten may be causing your symptoms, the first step is not to remove gluten.
The first step is to find out what might actually be going on.
What Is Gluten?
Gluten is a group of proteins found mainly in wheat, barley and rye.
It is found in many familiar foods, including bread, pasta, cakes, biscuits and many breakfast cereals. Gluten can also occur in processed foods such as sauces, soups and ready meals. Coeliac UK: What is gluten?
Because so many foods contain wheat or other gluten-containing cereals, symptoms that appear after eating them can be easy to notice.
But that does not automatically mean gluten itself is the cause.
“Gluten Intolerance” Can Mean Several Different Things
This is the most important point in the article.
Coeliac Disease
Coeliac disease is an autoimmune condition. Eating gluten triggers an immune response that damages the small intestine lining and can interfere with nutrient absorption.
It is not an allergy, and it is not simply a food intolerance. NHS: Coeliac disease
Wheat Allergy
Wheat can also cause an allergic reaction.
Food allergy symptoms can include hives, swelling, wheezing, vomiting, or other symptoms that develop after eating the food. Wheat is one of the foods that can cause a food allergy. NHS: Food allergy
Non-Coeliac Gluten Sensitivity
Some people report symptoms when eating gluten-containing foods but do not have coeliac disease or a wheat allergy.
This is often described as non-coeliac gluten sensitivity.
It is a less clearly defined condition, and no single diagnostic blood test has been established. Coeliac UK notes that symptoms can overlap with coeliac disease and that other components of wheat-containing foods, including FODMAPs, may contribute to symptoms in some people. Coeliac UK: Non-coeliac gluten sensitivity
That is why simply feeling better after removing gluten does not, by itself, prove that gluten was the cause.
What Symptoms Can Be Linked With Coeliac Disease?
Coeliac disease can produce digestive symptoms, but symptoms vary considerably between people.
The NHS lists symptoms including:
- diarrhoea
- stomach pain
- bloating and flatulence
- indigestion
- constipation
- vomiting
- persistent tiredness
- unexplained weight loss
Some people have only mild symptoms, while others have very few or no obvious symptoms. NHS: Symptoms of coeliac disease
This is one reason why trying to diagnose yourself from symptoms alone is unreliable.
Bloating, diarrhoea, constipation and tiredness can have many possible causes.
What Symptoms Suggest a Wheat Allergy?
Food allergies can behave differently from coeliac disease.
Symptoms may include:
- itching or hives
- swelling
- wheezing or breathing difficulty
- vomiting
- stomach symptoms
The NHS explains that wheat is one of the foods that can cause an allergy and that people suspected of having a food allergy may be referred for specialist testing. NHS: Food allergy
A reaction involving breathing difficulty, swelling of the mouth or throat, collapse or other severe symptoms can be an emergency.
How Is Coeliac Disease Diagnosed?
If coeliac disease is suspected, a GP can arrange a blood test.
NHS guidance says testing should be considered for people with persistent unexplained gastrointestinal symptoms and a number of other circumstances, including prolonged fatigue, unexpected weight loss, unexplained iron, vitamin B12 or folate deficiency, type 1 diabetes, autoimmune thyroid disease, IBS in adults, and a first-degree relative with coeliac disease. NHS: Diagnosis of coeliac disease
A blood test commonly looks for antibodies associated with coeliac disease.
In some cases, further specialist assessment and a small-intestine biopsy may be required. NHS: Diagnosis of coeliac disease
The Most Important Rule: Do Not Go Gluten-Free Before Testing
This is the part that deserves bold type.
Do not start a gluten-free diet before you have been tested for coeliac disease unless your healthcare professional has specifically advised you to do so.
NICE says coeliac testing is accurate only when you eat a gluten-containing diet during the diagnostic process. It recommends that people following a normal diet eat some gluten in more than one meal every day for at least 6 weeks before testing. NICE: Coeliac disease recommendations
Why?
Because removing gluten can reduce the antibody response the blood test looks for.
The result may then be misleading.
Coeliac UK likewise advises continuing to eat gluten until all required testing is complete. Coeliac UK: Getting diagnosed
So the well-meaning advice to “try going gluten-free and see if you feel better” can actually make a proper diagnosis harder.
What If You Have Already Stopped Eating Gluten?
Do not panic.
But tell your GP.
NICE advises that people who have already restricted or excluded gluten and are unable or unwilling to reintroduce it may need referral to a gastrointestinal specialist because confirming the diagnosis can become more difficult.
Coeliac UK also recommends discussing reintroduction with your GP rather than simply guessing how much gluten you need to eat.
Are Home Gluten Tests Reliable?
Be careful.
There are commercial home-testing kits and a large number of online tests claiming to identify food intolerances, allergies or gluten-related problems.
They are not a substitute for a medical diagnosis of coeliac disease.
Coeliac UK states that home testing kits do not provide a confirmed diagnosis and that alternative tests such as hair analysis, applied kinesiology, IgG gliadin tests and similar methods are not accepted methods of diagnosing coeliac disease. Coeliac UK: Home tests
A test result may look scientific without actually answering the important medical question.
What About IgG Food Intolerance Tests?
These tests are widely advertised online.
They are not the way coeliac disease is diagnosed.
Coeliac UK specifically lists IgG gliadin antibody tests among tests it does not regard as accurate or reliable for diagnosing coeliac disease.
So paying for a large panel that claims to identify dozens of “food intolerances” is not a sensible substitute for a proper clinical assessment.
Could It Be IBS Instead?
Possibly.
Irritable bowel syndrome can cause abdominal pain, bloating and changes in bowel habit, and symptoms may be affected by eating.
NICE recommends testing for coeliac disease in adults who meet the criteria for IBS, because coeliac disease can resemble IBS.
That is another reason not to assume that symptoms after bread or pasta automatically mean gluten intolerance.
The food may trigger symptoms without gluten being the sole cause.
What About FODMAPs?
Some people notice that bloating and other digestive symptoms improve when they reduce certain fermentable carbohydrates known as FODMAPs.
Wheat-based foods can contain FODMAPs, and Coeliac UK notes that researchers have questioned whether symptoms attributed to gluten in some people may actually relate to other components of wheat or the wider diet.
This does not mean FODMAPs explain everyone’s symptoms.
It means that the phrase “gluten intolerance” can sometimes hide a much more complicated digestive picture.
What Happens If You Test Positive for Coeliac Disease?
A positive blood test does not mean you should simply diagnose yourself and start buying gluten-free bread.
NHS guidance says people with positive antibody tests may be referred to a specialist, who can arrange further assessment and, where appropriate, a small-intestinal biopsy.
If coeliac disease is confirmed, a lifelong gluten-free diet is the main treatment.
You may also need assessment for nutritional deficiencies or other effects of the condition.
The important thing is knowing what you are treating.
What If Coeliac Disease Is Ruled Out?
That does not mean your symptoms are imaginary.
It means you need to consider another explanation.
Depending on your symptoms, a healthcare professional might consider IBS, food allergy, another gastrointestinal condition, lactose intolerance or other dietary factors.
Non-coeliac gluten sensitivity may also be considered after coeliac disease and other causes have been assessed. There is currently no single diagnostic test that confirms it.
That is much safer than assuming gluten causes every digestive complaint.
Should You Try a Gluten-Free Diet Anyway?
This depends on the circumstances.
If coeliac disease has not been ruled out, do not begin a gluten-free diet simply as a home experiment.
If appropriate medical testing has been completed and another reason for your symptoms has not been identified, a healthcare professional may discuss whether a trial of dietary changes is reasonable.
The important thing is to make dietary changes in a way that still provides a balanced intake of fibre, protein, vitamins and minerals.
Gluten-free does not automatically mean healthy.
Many gluten-free packaged foods are still highly processed and can be high in sugar, salt or saturated fat.
Is a Gluten-Free Diet Automatically Healthier?
No.
For somebody with coeliac disease, avoiding gluten is medically necessary.
For everybody else, there is no general requirement to avoid gluten.
The NHS Eatwell Guide recommends a varied eating pattern that includes fruit and vegetables, higher-fibre starchy foods, protein foods, dairy or alternatives and unsaturated fats.
For most people, wholegrain foods such as oats, wholegrain bread, brown rice and wholewheat pasta can be useful parts of a balanced diet.
Removing them all without a clear reason can make it harder to get enough fibre and variety.
What Should You Do If Bread Makes You Feel Ill?
Rather than immediately blaming gluten, keep a simple record for a short period.
Note:
- what you ate
- the portion size
- when you ate it
- when symptoms appeared
- which symptoms occurred
- whether anything else was different that day
This is not a diagnostic test.
It simply gives you something useful to discuss with your GP or dietitian.
It can also reveal patterns you might otherwise miss.
A large takeaway containing bread, cheese, sauce and other ingredients may produce a very different reaction from a small serving of plain toast.
When Should You See a Doctor?
Seek medical advice if symptoms are persistent, recurrent, or interfere with everyday life.
It is particularly important to seek medical assessment if you have symptoms associated with possible coeliac disease, such as unexplained weight loss, persistent gastrointestinal symptoms, prolonged fatigue, iron-deficiency anaemia or other unexplained nutrient deficiencies.
Do not rely on a self-imposed gluten-free diet to tell you what is happening.
And if you experience signs of a severe allergic reaction, such as difficulty breathing or swelling of the mouth or throat, seek emergency medical help.
The Bigger Picture
The question “Am I gluten intolerant?” sounds simple.
The answer often is not.
You could have coeliac disease, a wheat allergy, non-coeliac gluten sensitivity, IBS or another digestive problem.
Those conditions are different.
The most useful first step, therefore, is not to remove gluten.
It is to get the right condition investigated.
Keep eating gluten while coeliac disease is being investigated unless a healthcare professional tells you otherwise.
Avoid unreliable online intolerance tests.
Do not assume that feeling better without bread proves that gluten was the cause.
Once you know what you are dealing with, build your diet around foods that keep you well while still providing the nutrients your body needs.
That is a much more useful answer than simply putting every digestive symptom into the “gluten intolerance” box.
For more information about how digestive health and diet interact, see How to Improve Digestion: Simple Habits for Better Gut Health.
For more about nutrition and dietary restrictions, read Special Nutritional Needs: When Your Diet May Need Extra Attention.
You can also see Nutrition Terms Explained: RDA, DRI, EAR, AI and UL for a plain-English guide to the reference values used in nutrition advice.
Medical Disclaimer
This information is provided for general educational purposes only. It is not intended to diagnose, treat or prevent any medical condition and should not be considered a substitute for advice from a qualified healthcare professional.
Symptoms that occur after eating wheat or gluten-containing foods can have several possible causes. Do not start a strict gluten-free diet before coeliac disease has been appropriately investigated unless your healthcare professional advises you to do so, because testing may become inaccurate.
Seek urgent medical help for signs of a severe allergic reaction, including difficulty breathing, swelling of the mouth or throat, collapse or severe symptoms.
Do not use this article as a substitute for individual medical assessment or professional guidance.