Food and the gut
Understanding gluten: its effect on the gut and when a temporary break might help
Gluten is a protein found in wheat, barley and rye. Most people digest it without difficulty. It must be avoided completely in coeliac disease, and some people without coeliac disease feel better when they reduce wheat. Before you stop gluten, have a blood test for coeliac disease, because the test becomes unreliable once gluten is removed. A trial break of four to six weeks, followed by a planned return, then gives a clear answer.
In short
- Three conditions are linked to wheat: coeliac disease, wheat allergy and non-coeliac wheat sensitivity.
- Test for coeliac disease before changing your diet.
- In many people who feel better off wheat, the trigger is its fermentable carbohydrate (fructan), not gluten.
- For people without these conditions, a gluten-free diet has no proven benefit and can lower fibre intake.
Where is gluten found?
In wheat in all its forms, including atta, maida, sooji (rava), dalia, bread, biscuits, noodles and pasta, and in barley and rye. It is also present in many sauces, soups and processed foods as a thickener. Oats do not contain gluten but are often contaminated with wheat during milling.
Rice, millets (ragi, jowar, bajra), maize, pulses, besan, potatoes, vegetables, fruit, dairy, eggs, fish and meat are free of gluten.
Which conditions are caused by gluten or wheat?
Coeliac disease
An autoimmune condition in which gluten damages the lining of the small intestine. It requires a strict gluten-free diet for life. See gluten sensitivity and coeliac disease.
Wheat allergy
An allergic reaction to wheat proteins, causing hives, swelling, wheezing or vomiting soon after eating. It is uncommon in adults.
Non-coeliac wheat sensitivity
Bloating, pain, altered stools, tiredness or “brain fog” after wheat, with negative tests for coeliac disease and allergy. It is diagnosed by a structured trial.
Is it the gluten, or something else in wheat?
Wheat contains fructans, fermentable carbohydrates of the FODMAP family. In people with IBS, fructans cause gas and bloating. Studies that tested gluten and fructans separately suggest that fructans are the trigger for many people who believe they are sensitive to gluten. This matters, because such people can often eat small amounts of wheat and do not need a strictly gluten-free diet. See the low FODMAP diet.
Why must I test before stopping gluten?
The blood test and biopsy for coeliac disease depend on the body’s reaction to gluten. Within weeks of a gluten-free diet they can turn negative, and the diagnosis is missed. Coeliac disease needs lifelong strictness, follow-up and family screening, so a firm diagnosis is important.
If you have already stopped gluten, tell your doctor. A period of eating gluten again is usually needed before testing.
How do I run a proper trial break?
Test first
A blood test for coeliac disease while you are still eating wheat daily.
Remove gluten for four to six weeks
Fully, including hidden sources. Keep a simple record of symptoms each week.
Bring it back
Reintroduce wheat for a week, for example two rotis a day, and watch what happens.
Decide
If there was no clear improvement, or no return of symptoms, gluten is not your problem and can stay in your diet. If symptoms clearly returned, continue to limit wheat to the amount you tolerate, and review with a doctor or dietitian.
What are the drawbacks of an unnecessary gluten-free diet?
- Less fibre and fewer B vitamins, if wheat is replaced with refined rice flour products
- More packaged “gluten-free” food, which is often higher in sugar and fat
- Expense, and difficulty eating with family and friends
- A missed diagnosis of coeliac disease, if testing was skipped
Replacing wheat with millets, pulses and vegetables avoids the first two.
When should I see a doctor?
See a doctor before a trial if you have diarrhoea, weight loss, anaemia, mouth ulcers, bone pain or a relative with coeliac disease. These call for proper testing and not a home experiment.
Questions patients ask me
Is gluten harmful for everyone?
No. For people without coeliac disease, wheat allergy or wheat sensitivity, whole wheat is a healthy food and a good source of fibre.
Will a gluten-free diet help me lose weight?
Not by itself. Weight changes on such diets come from eating fewer refined and packaged foods. Many gluten-free products are high in calories.
Are millets better than wheat for the gut?
Millets are free of gluten, rich in fibre and well suited to Indian cooking. They are a good choice, with or without a gluten problem. Variety across grains is better than relying on any one.
Can I be sensitive to wheat even if my coeliac test is negative?
Yes. Non-coeliac wheat sensitivity is recognised. It is confirmed by a trial break and return, as described above.
Sources
This page is written for patients and is based on the guidelines and studies below. It is for education and does not replace a consultation.
- American College of Gastroenterology guideline on coeliac disease. Rubio-Tapia A et al. Am J Gastroenterol. 2023. PubMed 36602836
- Salerno experts’ criteria for non-coeliac gluten sensitivity. Catassi C et al. Nutrients. 2015. PubMed 26096570
- Community study of coeliac disease prevalence in northern India. Makharia GK et al. J Gastroenterol Hepatol. 2011. PubMed 21182543
- American College of Gastroenterology guideline on irritable bowel syndrome. Lacy BE et al. Am J Gastroenterol. 2021. doi:10.14309/ajg.0000000000001036
- Blinded crossover trial of gluten and fructan in people with self-reported gluten sensitivity. Skodje GI et al. Gastroenterology. 2018. doi:10.1053/j.gastro.2017.10.040