Gluten and wheat in IBS: Are they really the problem?

A 2025 study found that gluten and wheat did not consistently trigger IBS symptoms in adults when compared with a placebo. Researchers suggested that expectations and beliefs about food may influence how symptoms are experienced in some people with IBS.

Content outline

• What is IBS?

  • What are the symptoms of IBS?

  • IBS causes

• Why do people with IBS avoid gluten and wheat?

• What did the 2025 study investigate?

  • How was the study conducted? 

• What did the researchers find?

  • What do these results mean? 

  • Does this mean gluten-free diets don’t help?

  • What role could the gut microbiome play?

• Practical tips for managing IBS symptoms

• Summary

For years, many people with irritable bowel syndrome (IBS) have believed that gluten and wheat are major triggers for their digestive symptoms. For this reason, many sufferers have cut out foods such as bread and pasta from their diet in the hope of reducing bloating, abdominal pain, diarrhoea, and fatigue.

Yet a study published in The Lancet Gastroenterology & Hepatology in 2025 suggests that the story may be more complicated than just wheat and gluten. Researchers have found that while many adults with IBS expected these food components to worsen their symptoms, the foods themselves did not always appear to be the true cause. In some instances, expectations and beliefs about food played a more surprising role.

Here, we explore the findings of this study and what it could mean for people living with IBS.

What is IBS?

IBS is a common, chronic condition that affects the digestive system. It is estimated that the global prevalence of IBS is around 14% [1]. IBS is a functional disorder, which means it looks normal but does not function as it should because of increased sensitivity to certain triggers and abnormal muscle contractions [2].

What are the symptoms of IBS?

IBS symptoms can vary from person to person, but usually include:

• abdominal pain or cramping

• bloating

• excess gas and wind

• diarrhea

• constipation

• changes in bowel habits

• feeling like you haven’t fully emptied your bowels

IBS affects millions of people across the world and can have a major impact on your daily life, work, sleep, and mental wellbeing.

IBS causes

The exact cause of IBS is unknown, but experts have classified it as a disorder of the gut-brain interaction (DGBI), which means there is a signalling or communication issue between the central nervous system in the brain and the enteric nervous system in the gut [3], also known as the gut-brain axis. The fault in this bi-directional communication pathway results in the classic IBS symptoms mentioned above. 

▶ Curious about the gut-brain interaction? Find out more in our guide.

Some researchers believe a combination of factors could be involved, including:

• gut microbiome composition changes

• increased gut sensitivity

• stress and anxiety

• low-grade inflammation

• diet and food intolerances

The last point is an interesting one because many people with BS cut specific foods from their diet without consulting professional medical advice, which can inadvertently lead to a worsening of their symptoms and disruptions in their gut microbiota. Two key food irritants are wheat and gluten. 

Why do people with IBS avoid gluten and wheat?

Many IBS sufferers believe that wheat and gluten are common triggers for their condition because they may feel uncomfortable after eating them. This has led to a surge in the popularity of gluten-free diets, even in people who do not have Celiac disease, with studies finding that up to 5% of the Western population follows a gluten-free diet of their own accord [4]. 

The problem is that wheat contains far more than just gluten. It also contains:

• fructans (a type of FODMAP carbohydrate)

• fiber

• structural proteins other than gluten

• fermentable compounds

These wheat components and other dietary or lifestyle factors can also trigger immune responses:

This can make it difficult to definitively conclude that gluten and wheat are the culprits in the onset of IBS symptoms. This has led researchers to investigate further.

What did the 2025 study investigate?

The study by Seiler and colleagues titled “Effect of gluten and wheat on symptoms and behaviours in adults with irritable bowel syndrome: a single-centre, randomised, double-blind, sham-controlled crossover trial”, explored whether gluten and wheat are common IBS triggers.

How was the study conducted?

The study was a randomized, double-blind, sham-controlled crossover trial that recruited 28 people with IBS who experienced improvement in their symptoms on a gluten-free diet. The participants were assigned to eat one of three different types of cereal bars, which looked identical and had the same taste, daily.

The bars contained:

1. Whole wheat

2. Purified gluten

3. Free from whole wheat and purified gluten, known as a sham challenge

The participants were told that any of the bars could worsen or cause their IBS symptoms. Researchers monitored digestive symptoms via participant self-reports and used stool samples to measure gluten intake by detecting gluten-immunogenic peptides. This was because neither the participants nor the researchers knew which bars each person consumed. 

What did the researchers find?

The results were surprising because the researchers found that all three bar types resulted in IBS symptoms in similar proportions across the participants:

Another key finding of the study was that the nocebo effect* did not worsen IBS symptoms in some people, despite them holding beliefs that gluten or wheat was the cause of their discomfort.

* The nocebo effect is where a person's negative expectations or beliefs, i.e. gluten or wheat, cause IBS symptoms to worsen or the actual effects, even if the treatment is inactive. It’s essentially the opposite of the placebo effect.

The nocebo effect also had a greater impact on the study itself: although most people reported eating the cereal bars in each arm of the study, immunogenic peptide analysis of stool samples suggested otherwise. For example, only 9 of 28 people actually ate the bars as directed by a dietitian, indicating that prior beliefs affected dietary adherence.

What do these results mean?

Ultimately, the major finding from this study is that although some people with IBS may be sensitive to gluten, for others, the belief that certain dietary choices are driving their symptoms and the decision to avoid foods that contain wheat or gluten are the cause of their symptom flare-ups. 

The findings of this study nicely support previous research on functional disorders and dietary perceptions. For example, in a study investigating the effect of fat on functional dyspepsia, researchers found that symptoms occurred after consuming high-fat foods and low-fat foods, which the individual perceived to be high-fat [5]. 

Another study by de Graaf et al (2024) found that people with non-celiac gluten sensitivity reported gastrointestinal symptoms when eating gluten and when they thought they were. Therefore, demonstrating a nocebo effect when perceiving that they were consuming gluten-containing foods [6]. The researchers acknowledged the importance of the gut-brain interactions in people who self-report gluten sensitivity.  

Does this mean gluten-free diets don’t help?

Not necessarily. Some people with IBS genuinely feel better when they follow a gluten-free or low-FODMAP diet. However, the results from this study suggest that gluten may not be the main problem for everyone, and so a blanket avoidance of gluten for everyone with IBS is not always necessary or beneficial.

What role could the gut microbiome play?

The gut microbiome may also influence how foods are tolerated. For example, evidence suggests that a dysregulated gut microbiome contributes to the progression of IBS [7], contributing to symptoms, including bloating, pain, and altered bowel habits.

Practical tips for managing IBS symptoms

Before you cut out foods or food groups from your diet, which can have adverse effects, there are several things you can do to help manage IBS symptoms. IBS triggers are often unique to you, so it is important to avoid assuming that gluten or wheat is always the main cause.

Some of the strategies you can try are:

1. Keep a food and symptom diary. Tracking your meals, snacks, and any symptoms you get will help you identify any patterns over time. Don’t forget to add your drinks, beverages like caffeine and alcohol can also contribute to digestive discomfort.

2. Avoid overly restrictive diets. Cutting out too many foods can reduce diet quality and increase stress around eating. It also increases the risk of nutritional deficiencies, as you may not get all the vitamins and minerals your body needs.

3. Manage stress. Practice mindfulness, walking, yoga, or seek cognitive behavioural therapy, which can all be beneficial for IBS, as stress is a common trigger.

4. Support gut health. Choose fibre-rich foods and targeted prebiotics, such as human milk oligosaccharides (HMOs), to support a healthy gut microbiome. 

5. Seek professional advice. If you have tried all of these tips and are still getting no relief or improvement in your symptoms, speak to a physician or a registered dietitian to rule out conditions, such as celiac disease. They can also help you make dietary changes safely.

Summary

Overall, the 2025 study adds to the growing evidence that gluten and wheat may not be the main drivers of IBS symptoms for everyone, and that, for some, the prior idea that gluten is the problem is driving symptom onset.

Although this is not the case for everyone, it is clear that IBS involves a complex mix of:

This highlights the importance of a personalized approach to IBS rather than assuming that one food is responsible.

If you’re looking to support your gut further, explore our range of HMO-based gut health solutions, especially the PureHMO® IBS Support with IBS Defend Probiotic.

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Author details

Written by: Leanne Edermaniger, M.Sc. Leanne is a professional science writer who specializes in human health and enjoys writing about all things related to the gut microbiome. She has written extensively on inflammatory bowel disease, prebiotics, and microbiome research.

Her work focuses on translating complex medical science into evidence-based, practical health guidance.