The Diet in IBS Research Study

The Diet in IBS Research Study is a clinical crossover research study which is the first to investigate the effects of dietary gluten and amylase trypsin inhibitors (ATIs) on irritable bowel syndrome (IBS). The trial is being led by Drs. Premysl Bercik and M. Ines Pinto-Sanchez in the Farncombe Digestive Disease Research Institute at McMaster University. The Study Coordinator is PhD Candidate Caroline Seiler and the co-investigators include Dr. Elena Verdu, Dr. Stephen Collins, Dr. Paul Moayyedi, and Dr. Andrea Nardelli. This study is supported by the Canadian Digestive Health Foundation and a Society for the Study of Celiac Disease (SSCD) grant for Non-Celiac Gluten/Wheat Sensitivity sponsored by the Nestle Research Center, Nestec SA to Drs. Bercik and Pinto-Sanchez. 

This study has been reviewed by the Hamilton Integrated Research Ethics Board under Project #4367.

Clinic Location:

Digestive Diseases Clinic (3rd Floor)
McMaster Children's Hospital
1200 Main Street West, room 3U35
Hamilton, Ontario

What’s Involved?

We will include adult patients with irritable bowel syndrome (IBS) whose symptoms improve on a gluten-free diet. Participants will be asked to follow a gluten-free diet for the duration of the study and will be asked to consume granola bars containing either gluten, whole wheat flour and gluten, or gluten-free flour (placebo). Participants will receive all three dietary challenges in a random order during a period of 10 weeks and their symptoms and gut function during each challenge will be assessed. The objective is to investigate the mechanisms by which wheat causes symptoms in IBS patients. If successful, the results of this project will provide evidence as to whether gluten or other wheat components trigger gastrointestinal symptoms in IBS patients. 

Who is Eligible?

Adults aged 18+ with an IBS diagnosis based on Rome IV criteria who previously improved while on a gluten-free diet, are able to comply with the study procedures, and have signed the Informed Consent may be eligible for the study.

Participants meeting one or more of the following criteria will be excluded:

  • Concurrent systemic disease and/or laboratory abnormalities considered by investigators to be risky or that could interfere with data collection
  • Concurrent benign pathology (i.e., celiac disease, inflammatory bowel disease, etc.) other than benign polyps, diverticulosis, hemorrhoids, lipoma, and melanosis coli
  • History of active cancer in the last 5 years, other than basal cells cancer
  • Pregnant or breastfeeding women
  • Currently participating in or having participated in a clinical study in the past month
  • Received antibiotics in the past month
  • Using new medications or changes of dosages in the past month
  • Major abdominal surgery with the exception of hernia repair, appendectomy, Cesarean section, tubal ligation and cholecystectomy, hysterectomy, and hemorrhoidectomy.

This trial is open to patients outside of Hamilton. Please speak to your doctor or contact the Study Coordinator if you are interested in participating in the study.

How is this study different from other studies?

There have been no studies in humans performed internationally evaluating the effects of amylase trypsin inhibitors (ATIs) on irritable bowel syndrome (IBS). Preliminary data have shown that ATIs found in the gluten-containing grains can cause inflammation in animals, but it is unknown whether there are similar effects in humans.

This study is different because it will be the first to assess the effects of ATIs compared to gluten in IBS patients. If some “gluten-sensitive” IBS patients react to ATIs but not to purified gluten, then this would allow for the production of gluten-containing, but ATI-free, foods that IBS patients would be able to safely consume.


During the COVID-19 pandemic, McMaster University placed restrictions on in-person research visits. While in-person research visits are restricted, we will perform home-based visits where study participants do not need to come to McMaster University. Instead, study visits will be conducted on Zoom, telephone, or Signal and the study interventions and the stool & urine collection kits will be mailed or dropped off at participant homes. The stool and urine samples will then be picked up during a contactless pickup to maintain social distancing. Once in-person visits resume, participants will come to McMaster University and blood samples and x-rays will be collected again. 

Safety Monitoring

Gluten and ATIs are suspected to cause gastrointestinal symptoms in people with IBS. Therefore, we expect that gluten- or ATI-sensitive individuals will have greater symptoms when they are eating the gluten- and ATI-containing granola bars. Further, because many IBS symptoms can be impacted by a person’s mental state, we expect that those who are on the gluten-free granola bars will also feel worse.

Throughout the trial, patients’ symptoms will be measured weekly using various questionnaires.

If any study participants have any unexpected symptoms or reactions, they will be encouraged to contact the Study Coordinator. The primary doctor will be informed and we will keep their family doctor informed of any adverse events.

Patients are able to withdraw from the study at any time and we will enforce strict safety monitoring guidelines to remove patients from the study if there are adverse events.

How were the granola bars made?

The granola bars for the study were created by the Study Coordinator, Caroline Seiler, and several volunteers. They are vegan and nut-free. Please contact us if you have any other allergies.

Special thanks to the certified gluten-free kitchen the Grass Roots Kitchen in Scarborough, ON, the In Good Company Kitchen in Oakville, ON, and the Tiny Shop Bakery in Dundas, ON for providing kitchen spaces to create the granola bars.

Granola bars in the oven

Frequently Asked Questions

How is this study different from others?

This study is the first to look at the effects of amylase trypsin inhibitors (ATIs) in humans. These proteins are high in modern North American gluten-containing grains like wheat, so it is possible that ATIs are the true culprits for the rise in gluten and wheat-sensitivity in North America. Therefore, this study will look at whether IBS patients get symptoms when they have gluten alone or if they only get symptoms from gluten and wheat contaminated with ATIs.

When is this study going to start?

We have started recruiting patients.

What will be done at each visit?

At each visit, you will be asked to complete questionnaires and provide urine and stool samples. If you attend in-person visits, you will provide blood samples at each visit and x-rays will be done at four visits to measure your colonic transit time.

Are patients outside of McMaster allowed to participate?

Yes. Please ask your doctor to contact us, or you can contact the Study Coordinator to speak to us directly.

What outcomes are being measured?

The primary outcome of this study will be to evaluate the effects of gluten and ATIs, compared to placebo, on IBS symptoms. This will be assessed using several questionnaires. Secondary outcomes will be to assess potential mechanisms including changes in blood inflammatory markers, gut motility, gut microbiota composition, and urine metabolites.

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