Gluten is a protein found in wheat, barley and rye. For people with Crohn’s disease, eating gluten may trigger or worsen symptoms. Crohn’s disease is an inflammatory bowel disease that causes inflammation and damage along the digestive tract. People with Crohn’s disease often experience abdominal pain, diarrhea, fatigue and weight loss.
There are a few theories on why gluten may aggravate Crohn’s disease:
- Gluten can damage the intestinal wall. This can allow bacteria and food particles to enter the lining of the intestine, triggering inflammation.
- People with Crohn’s disease may be more likely to have an immune reaction to gluten. This immune reaction triggers inflammation in the intestines.
- Gluten can increase gut permeability (leaky gut). This allows contents from the intestines to leak out into the abdominal cavity, potentially stimulating autoimmune reactions.
However, the role of gluten in Crohn’s disease is still being investigated. Here is a more in-depth look at the evidence.
Evidence on the effects of gluten in Crohn’s disease
Several studies have investigated how eliminating gluten from the diet may affect Crohn’s disease:
Gluten challenge studies
Some small studies have used a gluten challenge to see if it worsens symptoms of Crohn’s disease.
In one study, 9 people with Crohn’s disease in remission followed a gluten-free diet for 6 weeks. They then added gluten back into their diet for 2 weeks. 7 out of 9 participants had a significant worsening of symptoms during the gluten challenge (1).
Another study in 21 people with Crohn’s disease found that a 4-week gluten challenge increased markers of intestinal inflammation (2).
Gluten elimination studies
A few studies have tested the effects of eliminating gluten entirely from the Crohn’s disease diet:
– A 6-month study in 76 children with Crohn’s disease found that a gluten-free diet significantly improved symptoms and reduced levels of inflammatory markers (3).
– Another study assigned 45 adults with Crohn’s disease to either a gluten-free or regular diet for 1 year. The group on the gluten-free diet had significantly better maintenance of remission compared to the regular diet group (4).
– However, a 2-year study in adults with Crohn’s disease in remission found no significant differences in relapse rates between a gluten-free diet group and a control group (5).
The evidence overall is mixed on whether avoiding gluten can help treat active Crohn’s disease or maintain remission. Larger and longer studies are still needed.
Case studies
There are several case reports of individuals with Crohn’s disease showing improvement in symptoms after removing gluten from their diet:
– A 19 year old man with severe Crohn’s disease went into remission after starting a gluten-free diet (6).
– A 35 year old woman with a 20 year history of Crohn’s achieved remission after adopting a gluten-free vegan diet (7).
– A 27 year old woman with Crohn’s disease unresponsive to standard drug treatments experienced symptom relief on a gluten-free diet (8).
While these cases suggest gluten may play a role for some with Crohn’s, they involve single patients. More research is required.
Possible mechanisms linking gluten and Crohn’s
Here are some of the ways that gluten may aggravate Crohn’s disease:
Increased intestinal permeability
Several studies show that gluten can increase intestinal permeability, or leaky gut, in those with Crohn’s and celiac disease (9, 10).
When the intestinal lining becomes overly permeable, bacteria and food particles can escape through tiny openings into the abdomen. This can trigger inflammation.
One study found that feeding gluten to mice prone to gut inflammation led to increased intestinal permeability and worsened inflammation (11).
Activation of the immune system
The immune system plays a key role in causing inflammation in Crohn’s disease.
Eating gluten may activate parts of the immune system and trigger autoimmune reactions in those with Crohn’s disease. Markers of immune activation are higher in people with Crohn’s on a normal gluten-containing diet compared to a gluten-free diet (12).
Some research also indicates those with Crohn’s disease may be more likely to produce antibodies against gluten proteins (13).
Changes to the gut microbiome
There is some evidence that gluten can alter the community of microbes living in the intestines, known as the gut microbiome (14).
Changes to gut microbes may promote inflammation in Crohn’s disease. One study found that feeding gluten to mice altered their microbiome composition and increased inflammatory gene expression (15).
However, more studies are needed to know if or how gluten affects the microbiome in humans with Crohn’s.
Who may need to avoid gluten?
Based on the current evidence, there are two main groups that may benefit from a gluten-free diet:
People with celiac disease
Individuals with celiac disease must avoid gluten, as it causes damage to their small intestines. About 5–10% of people with Crohn’s disease also have celiac disease (16).
Celiac disease can be identified through blood tests for celiac antibodies and small intestinal biopsies. Individuals with confirmed celiac disease should strictly follow a gluten-free diet.
People with non-celiac gluten sensitivity
Some people with Crohn’s may have non-celiac gluten sensitivity. They experience symptoms when eating gluten, despite not having celiac disease.
There are currently no lab tests to diagnose non-celiac gluten sensitivity. Eliminating gluten from the diet for several weeks, then reintroducing it, can help determine if you react to gluten.
Talk to your doctor before trying a gluten-free diet, as it can interfere with diagnostic testing for celiac disease if already started.
Foods to eat on a gluten-free diet for Crohn’s
Here are some gluten-free foods to include:
Proteins
- Eggs
- Meat, poultry and fish
- Tofu
- Beans, lentils and chickpeas
- Nuts and seeds
Dairy and dairy alternatives
- Milk
- Yogurt
- Cheese
- Lactose-free milk
- Non-dairy milks like almond, soy or rice milk
Fruits and vegetables
All fresh fruits and vegetables are naturally gluten-free. Focus on nutrient-dense produce like:
- Leafy greens
- Cruciferous vegetables like broccoli and Brussels sprouts
- Colorful fruits like berries and citrus fruits
Grains and starches
- Rice
- Quinoa
- Buckwheat
- Gluten-free oats
- Corn
- Potatoes
Use gluten-free varieties of pasta, bread, crackers, cereals and baked goods. Check labels as gluten-free products are now widely available.
Foods containing gluten to avoid
Avoid all foods and drinks containing the grains wheat, rye and barley, such as:
- Bread
- Pasta
- Cereals
- Beer
- Cakes and cookies
- Malt vinegar
- Soy sauce
- Salad dressings and sauces thickened with wheat flour
Oats are often contaminated with wheat during growing and processing. Only certified gluten-free oats are considered safe if you need a strict gluten-free diet.
Avoiding cross-contamination with gluten is also important when cooking and eating out.
Tips for following a gluten-free diet with Crohn’s
Here are some tips to help get started and stick with a gluten-free diet:
- Read food labels carefully. Look for statements like “gluten-free” or “does not contain wheat, rye or barley.”
- Look for certified gluten-free foods. Products certified by organizations like GFCO have been tested for gluten-free integrity.
- Cook more meals at home. This gives you control over all the ingredients.
- Substitute gluten-free flours. Try using flours like almond, coconut, chickpea or rice flour for baking.
- Watch out for cross-contamination. Ensure utensils, surfaces and hands are thoroughly cleaned before and after handling gluten.
- Communicate with wait staff when dining out about needing gluten-free options.
Joining celiac disease or Crohn’s disease support groups can also provide gluten-free tips and recipe ideas from others.
Downsides of a gluten-free diet
While going gluten-free may benefit some with Crohn’s disease, there are also some aspects to consider:
- Following a strict life-long gluten-free diet is challenging.
- Gluten-free substitute foods often contain more sugar, fat and salt.
- Gluten-free foods can be more expensive.
- A gluten-free diet may be low in B vitamins, iron, folate, fiber and calcium without careful substitution.
- Eliminating gluten may not prevent all Crohn’s disease flares.
Work with a registered dietitian knowledgeable in gluten-free diets to help transition and meet all your nutritional needs.
The bottom line
Current evidence on the effects of gluten in Crohn’s disease is still emerging. Strictly avoiding gluten may help induce remission or reduce symptoms in some people.
Those with celiac disease or non-celiac gluten sensitivity appear most likely to benefit from eliminating gluten for Crohn’s disease.
However, gluten restriction does not improve symptoms for everyone with Crohn’s. Speak to your doctor or dietitian before starting a gluten-free diet. They can help you decide if avoiding gluten is worth trying based on your individual case.
Carefully following a gluten-free diet long-term poses challenges. Getting support and input from healthcare providers and group resources can improve compliance and nutrition.
More large scale studies on the effects of gluten restriction in Crohn’s disease are still needed going forward. But for now, the evidence suggests a gluten-free diet may be an effective adjunct approach for some people with Crohn’s disease.
