Most patients suffering from the irritable bowel syndrome (IBS) report that ingestion of certain foods is a major trigger of symptoms, but the reason is unclear. Previous studies have shown that foods containing poorly absorbed carbohydrates (FODMAPs) are fermented by the bacteria in our bowels and these cause symptoms in some, but not all patients. Gut bachiteria are capable of producing various products, such as histamine, that may be related to IBS symptoms. Our recent data suggest that consumption of FODMAPs promotes production of bacterial histamine.


What the study involves:

  • 6 weeks on a low-FODMAP diet
  • 3 interventions consisting of High- or Low-FODMAP drinks along with probiotics or placebo capsules.
  • Food diary
  • 5 stool samples
  • 7 urine samples

Eligible participant descriptors:

  • Age 18-75
  • IBS diagnosis (as diagnosed by your physician)
  • Previous improvement of IBS symptoms when excluding certain foods


You will be compensated for your time at each study as well as any parking expenses



Dr. Premysl Bercik, Dr. Pedro Miranda


Study Funding Source:

Canadian Institutes of Health Research (CIHR) IMAGINE SPOR-Network Incubator Research Grant


Research Coordinator Contact:

Name: Pedro Miranda



Frequently Asked Questions


What are FODMAPs

FODMAPs are fermentable carbohydrates. This means that they are sugars that are poorly absorbed in the digestive tract, and so they reach the large intestine where bacteria are able to metabolize them instead. This process results in the production of gas, the accumulation of water, and the production of other chemicals which are thought to cause symptoms in some IBS patients.

Many foods contain FODMAPs including milk products, certain fruits and vegetables, legumes, some grains, and various sweeteners. The study dietician will provide a more comprehensive education on FODMAPs and which foods to avoid while on the low-FODMAP diet.


What are the challenges?

The challenges consist of 5 days of probiotics or placebo and 3 days of high- or low-FODMAP drinks along with L-histidine amino acid supplements.


How long are each of the visits?

30 - 60min


How will my samples be used?

  • Questionnaires: To assess any changes in your physical and psychological symptoms
  • Food Diary: To quantify FODMAP intake
  • Blood Samples: To assess circulating chemicals in the blood which change the behavior of the gut:
  • Urine Samples:  To assess the chemicals in the urine
  • Stool Samples: To assess the nature of the bacteria, present in the stool, which change the behavior of the gut.

What are the risks?

  • Questionnaires: it is possible that some questionnaires might be surprising or distressing to read because they ask questions about topics you may avoid thinking about.
  • Blood Samples: As with all routine blood draw procedures, the risks are minimal. They include slight discomfort, bruising at the site of the needle puncture and minor bleeding. Fainting, infections and nerve damage are very rare complications.
  • Urine/Stool Samples: No risk
  • Challenges: it is possible you will have an increase in gastrointestinal symptoms. However, the researchers do not expect symptoms to be severe or long lasting. In addition, there may be unknown risks. Please discuss any concerns you may have with your study doctor.

How will my privacy be maintained?

To protect your identity, the information that will be on your samples and questionnaires will be limited to your study ID number. A list linking this ID number with your name will be kept in a secure place, separate from your study file. Data will be stored in locked files and available only to Dr. Bercik, his co-investigators, and Health Canada. Any records pertaining to this study will be kept for 25 years. You will not be identified in any publications or reports. There is a possibility that your medical record, including identifying information, may be inspected by Health Canada, in the course of carrying out regular government functions.

Your family doctor/health care provider may be informed that you are taking part in a study if required. If you do not want your family doctor/health care provider to be informed, please discuss this with the study team


What if I don’t want to continue the study?

It is always your choice whether to participate in the study or not. Choosing not to participate, or deciding you no longer want to participate will not affect the treatment or care to which you would normally be entitled.

If you no longer want to participate in the study, inform the study coordinator at any time. You will be removed immediately, without question. If you do not want your previous samples or information to be used, they will be destroyed.


This study was approved by the Hamilton Integrated Research Ethics Board (#8342).

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