Efficacy of Low-FODMAPs Dietary Therapy for Irritable Bowel Syndrome in China

The primary aim of our study is to carry out a randomized trial to evaluate the efficacy of low-FODMAPs dietary therapy compared to conventional therapy for IBS patients recruited from tertiary hospitals in China. Secondary aims of this research include an analysis of clinical, physiological and microbiological factors that may predict IBS patient response to this dietary intervention.

Visit 1：Enrollment \& Screening \& Run-in period Patients who meet the inclusion criteria will be asked to complete IBS Baseline Assessment Questionnaires according to Rome III.Subjects that meet the criteria will receive verbal and written information about the study and provide written informed consent. After meeting with the dietitian and physician who will provide instructions, they will be asked to complete Combined Nutrient and Lactulose Breath Test.\[16\] Additionally, a baseline food and symptom diary will be completed in a (minimum) 14 day run-in period after breath test (the first 48hr after the breath test will not be included in this analysis). This diary record prior to the intervention will document baseline symptom severity and capture the habitual diet of IBS patients.

Visit 2: Randomization \& Intervention. After the run-in period, patients will come back to the clinic to receive dietary instruction ahead of starting the intervention. At the same visit subjects will provide fresh stool for fermentation analysis (including short chain fatty acids and pressure detection) and blood for cytokines analysis. Subjects will then be randomly assigned to either low FODMAP diet (LFD) group or traditional dietary advice for IBS (TDA) group by computer-generated random number table. Participants will receive food instructions by a dietitian, according to their assignment. Throughout the study, only the dietitian will be aware of the assignment of the intervention given. Both diet therapy will last for 3 weeks, and all the subjects are instructed to complete daily food and symptom diary through a provided booklet. IBS Symptoms Severity Scores (IBS-SSS) is evaluated every week and the dietitian who is not aware of the allocation will make a telephone follow-up to assess patient adherence.

Visit 3: End of treatment \& Follow-up. After 3 weeks of intervention, the participants will attend a follow-up appointment and complete the IBS Post-Intervention Assessment Questionnaires. Fresh stools and blood are recollected at this visit to evaluate for possible change in gut microbiota and cytokines after diet intervention.

Eligibility Criteria:
Inclusion Criteria:

* 18-65 years old.
* Meet Rome Rome III criteria for IBS-D.
* All these patients should have no abnormality in blood, stool analysis or colonoscopy within the previous 2 years.
* No GI alarm symptoms.

Exclusion Criteria:

* Presence of a severe cardiac, hepatic, nephritic, neurologic disease.
* Presence of mental disorders caused by schizophrenia, organic brain disorder or physical disease.
* Other comorbid medical conditions (eg.unstable diabetes, unstable thyroid disease).
* Previous abdominal surgery except appendectomy or hysterectomy.
* Pregnant or lactating women.
* Use of probiotics, prebiotics, lactulose, antidiarrheal agents or bowel preparation within the 4 weeks prior to the study.
* Participation in any other form of dietary therapy within the 4 weeks prior to the study.
* Difficulties in communication.