Gluten in our food is a topic that has grown in popularity for both individuals with IBD and the general population. We are living in the age of gluten-free products. Are these always better for IBDers? Considering many gluten-free products are still processed foods full of other potential triggers – probably not. Nonetheless, there is growing evidence that gluten can increase intestinal inflammation and intestinal permeability, both highly implicated mechanisms in IBD.

What exactly is gluten and why are we so worried about it?

“Gluten” refers to a class of proteins (mostly gliadin and glutenin) found in wheat and other grains. These proteins have specific structures that, when combined with water, form a sticky glue-like matrix that is fundamental to the texture of many processed foods we have learned to love, such as bread, sauces, pasta, and other baked goods. Despite its useful properties, as gluten-containing foods have risen in prevalence in the Western diet, so have several gluten-related disorders, including celiac disease, gluten allergy, and non-celiac gluten sensitivity. (1)

Celiac disease, reported in about 1% of the general population, is a chronic immune-mediated enteropathy triggered by the ingestion of gluten. Interestingly, there is evidence that celiac disease is associated with microscopic colitis, a type of Inflammatory bowel disease.(2) Gluten allergy, on the other hand, does not cause the intestinal damage seen in celiac disease. It is reported in 0.05-9% of the population and includes having gastrointestinal or respiratory symptoms after ingestion of wheat-containing foods.(3) Lastly, non-celiac gluten sensitivity (NCGS) is when, in the absence of celiac disease or a gluten allergy, individuals still experience both intestinal or extra-intestinal symptoms after ingesting gluten-containing foods. 

It is still not completely clear exactly why this cluster of proteins is problematic in a growing portion of the population, but gluten has certainly become a hot topic of debate even outside of the medical establishment and academic circles. In this blog we will uncover research performed on gluten and it’s subsequent altercations on gut physiology in people with IBD.

The relationship between gluten products and IBD diets

The controversy surrounding gluten pervades even the IBD community. Many health professionals consider it to be a trigger food for those with any kind of GI distress, yet there is no general consensus to recommend avoiding it. Nonetheless, most diets designed to promote healing in both CD and UC tend to avoid foods with gluten. For example, the specific carbohydrate diet (SCD), a common grain-free diet created for people with IBD, is based on a theory that you can heal your intestinal barrier and stop inflammation by avoiding complex carbohydrates, including gluten-containing foods. This is based on the idea that the digestion of complex carbohydrates causes dysbiosis, an imbalance of bacteria in our gastrointestinal tract, which then leads to damage of the mucosal layer.(4)

The low-FODMAP diet (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) is another dietary approach that addresses gluten consumption for people with IBD. It focuses on consuming food low in fermentable carbohydrates. This diet is also low in gluten-containing foods as those foods often are composed of fructose and fructans (types of FODMAPs). More research is needed to describe the exact role gluten has in the success rates seen in people with IBD on a low-FODMAP diet.(5)

The Briggs Protocol, an IBD protocol we have examined at IBDCoach, suggests avoidance of gluten on the basis that many IBD patients have difficulty with gluten-containing foods. Briggs, an IBD patient expert, brings up an interesting point in his protocol, stating, “Modern wheat has been selectively bred for rapid growth, which has unintentionally resulted in high levels of gliadin.” Gliadin is a component of gluten that is shown to contribute to increases in intestinal permeability (discussed more below).

When considering why these relevant IBD diets exclude gluten products, we are led to wonder, in which food is gluten most commonly found? The answer is of course, in processed foods like bread, pastries, crackers, and so on. So is it the processing of the food that is the problem, or is it the gluten itself? When removing these products from our diet, do we see improvement in our symptoms strictly because of gluten? Some would argue improvement is also due to the exclusion of other additives found in processed foods, along with the substitution of more nutritious foods you may be intaking to replace the gluten-containing products.

What does the scientific evidence say?

Currently, there is no universal recommendation for consuming a gluten-free diet in the treatment of IBD. The dietary guidelines recently released by the International Organization For the Study of Inflammatory Bowel Disease (IOIBD) reported there was insufficient evidence to conclude people with IBD should avoid gluten. Although there aren’t many studies focusing on how a gluten-free diet (GFD) may alleviate GI symptoms, there is a decent amount of preliminary data suggesting gluten alters our microbiota, increases intestinal inflammation, and contributes to GI symptoms. 

One of the largest patient-reported studies performed on 1647 patients with IBD resulted in 65.5% of patients who attempted a GFD describing an improvement of their GI symptoms. Additionally, 38.3% of participants reported fewer or less severe IBD flares.(6) These results suggest that in a subgroup of IBD patients, gluten may be the culprit for intestinal symptoms (diarrhea, bloating, abdominal pain). 

To understand why gluten may be causing GI issues, we can look at the molecular pathway by which gluten disrupts the gut barrier. When one of the proteins that gluten is composed of, gliadin, reaches our intestinal cells, another protein called zonulin is released. Zonulin signals to our GI cells to increase the space in between them, causing gut junctions to grow wider, resulting in an increase in intestinal permeability which contributes to an immune response.(7) In an animal model of colitis, wheat gluten increases the severity of disease by weakening these tight junction proteins and increasing intestinal permeability and bacterial translocation.(8) In other words, the consumption of gluten sets off a chain reaction that leads to bacteria slipping through the cracks of the intestinal barrier, which then causes a painful inflammatory response.

As we know, lifestyle changes, especially relating to diet, results in changes to our microbiota. One preliminary study has been performed to investigate whether a GFD leads to modifications on the composition and immune properties of the gut microbiota. This study followed 10 healthy subjects on a GFD for over a month and found decreased proportions of the bacteria Bifidobacterium. Interestingly, these subjects following a GFD also presented a reduction of bacterial-induced cytokine production compared to controls, suggesting immune suppressive effects.(9) A more extensive randomized controlled trial confirmed these microbiota-altering effects. Researchers in Denmark studied 60 adults during an 8-week dietary intervention comparing both a low-gluten diet and a high-gluten diet. The low-gluten diet resulted in reductions in certain bacterial species that contribute to carbohydrate metabolism (Bifidobacterium, Eubacterium halli, Anaerostipes,etc). In both of these studies, a decrease of the protective bacteria, Bifidobacterium, was observed. This may be due to an overall decrease in dietary carbohydrates that feed these species.(10)Overall, more research needs to be completed in order to understand whether these changes to the composition and function of our microbiota by a GFD are beneficial long term, but it seems that there is a strong biological basis to the negative symptoms experienced by many individuals when they consume gluten. 

Even though gluten proteins are known to have negative effects on the GI system, when attempting to avoid gluten it is important to consider the makeup of the foods we use as a substitution. Additives in many gluten-free products like thickeners and binders used to simulate the stickiness of gluten may be detrimental to the GI as well. Prioritizing foods containing prebiotics to feed healthy gut microbes, especially the species we know to produce helpful short-chain fatty acids (SCFAs), important fuel for our intestinal epithelial cells known to strengthen the gut barrier function.(11)

In addition to effects on gut function, some experts state gluten consumption influences mental health and cognitive function. Since the popularization of the bestselling book Grain Brain by Dr. David Perlmutter, many readers have wondered how gluten and carbs may induce a “grain brain” described as a sort of brain fog. Dr. Alessio Fasano explains how gluten causes inflammation not only in the gut by way of an increase in gut permeability, but also in the brain by way of an increase in permeability of the blood-brain barrier. 


Overall, since the mass production of wheat and the increase in gluten in the makeup of the Western diet, we have seen a parallel increase in intolerances to gluten. It has been shown now through scientific studies that gluten has an effect of increased intestinal permeability, and avoidance of gluten has even been shown to improve GI symptoms for some individuals with IBD. More research is necessary to determine an official recommendation for IBD and further understand the implications on our microbiome.  

Like all dietary strategies employed for IBD, what works for one person may not work for all; one person’s “trigger food” may pose no threat to another person. Depending on your state of disease and how you are feeling, we encourage you to always listen to your individual body. If you feel inclined to eliminate gluten after reading about the scientific evidence that associates wheat with various intestinal and extraintestinal symptoms, be sure to speak with your medical team to ensure adequate nutrition. Any major dietary changes will benefit from documentation in a food journal to take note of how you are feeling after limiting certain foods. It may take some time to identify which dietary strategies work best for you, so consistent documentation will be helpful in identifying larger patterns.

Here at IBDCoach we want to help you find what strategies will help you heal. While we share with you the current evidence, we’d love to hear your personal experience. Have you tried a GFD before? What foods did you substitute and how did it make you feel?


  1. Biesiekierski, J. R. What is gluten? J. Gastroenterol. Hepatol. 32, 78–81 (2017).
  2. Weaver, K. N. & Herfarth, H. Gluten-Free Diet in IBD: Time for a Recommendation? Mol. Nutr. Food Res. n/a, 1901274.
  3. Gujral, N., Freeman, H. J. & Thomson, A. B. R. Celiac disease: prevalence, diagnosis, pathogenesis and treatment. World J. Gastroenterol. 18, 6036–6059 (2012).
  4. Science Behind the Diet – Breaking the Vicious Cycle.
  5. Cox, S. R. et al. Effects of Low FODMAP Diet on Symptoms, Fecal Microbiome, and Markers of Inflammation in Patients With Quiescent Inflammatory Bowel Disease in a Randomized Trial. Gastroenterology 158, 176-188.e7 (2020).
  6. Herfarth, H. H., Martin, C. F., Sandler, R. S., Kappelman, M. D. & Long, M. D. Prevalence of a gluten free diet and improvement of clinical symptoms in patients with inflammatory bowel diseases. Inflamm. Bowel Dis. 20, 1194–1197 (2014).
  7. Fasano, A. Zonulin and its regulation of intestinal barrier function: the biological door to inflammation, autoimmunity, and cancer. Physiol. Rev. 91, 151–175 (2011).
  8. Menta, P. L. R. et al. Wheat gluten intake increases the severity of experimental colitis and bacterial translocation by weakening of the proteins of the junctional complex. Br. J. Nutr. 121, 361–373 (2019).
  9. Sanz, Y. Effects of a gluten-free diet on gut microbiota and immune function in healthy adult humans. Gut Microbes 1, 135–137 (2010).
  10. O’Callaghan, A. & van Sinderen, D. Bifidobacteria and Their Role as Members of the Human Gut Microbiota. Front. Microbiol. 7, (2016).
  11.  Parada Venegas, D. et al. Short Chain Fatty Acids (SCFAs)-Mediated Gut Epithelial and Immune Regulation and Its Relevance for Inflammatory Bowel Diseases. Front. Immunol. 10, 277 (2019).

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