irritable bowel syndrome (IBS) is a well-known risk factor for diseases of the anal region (hemorrhoids, anal fissures, etc.) and large intestine (colon cancer, diverticular disease). Untreatable IBS disease not only impairs the patient's quality of life but also reduces the success of surgical treatment in these diseases.

Today, only one-third of IBS patients achieve successful results with the treatment methods and diets used routinely. Balancing the composition of the gut microbiota may yield satisfactory results in this patient group. With the results of our study, we aim to reveal the effect of microbiome analysis and personalized diet on symptoms and its place in treatment in patients with IBS disease.

Patients applying to Gastroenterology outpatient clinics in respective centers due to IBS will be randomized into two groups. The patients in the control group will follow the FODMAP diet protocol for IBS; In the study group, a personalized diet will be applied according to the gut microbiota. No nutritional supplements will be used in either group. Changes in defecation habits and quality of life scale of both groups will be evaluated at the end of 6 weeks and the results will be compared.

Inclusion Criteria:

• To be between the ages of 18-65
• To be diagnosed with IBS (IBS-D, IBS-C, IBS-M) according to the Rome IV Criteria
• To give consent to participate in the study voluntarily
• Being a smartphone and/or internet user (for dietitian follow-up and clinical follow-up)
• Not meeting any of the exclusion criteria

Exclusion Criteria:

• Pregnant or planning to become pregnant
• Having another known diagnosis of gastrointestinal disease (inflammatory bowel disease, malabsorption of any macronutrient, intestinal resection, celiac disease, etc.)
• Colonoscopy history (in the last 1 year)
• History of abdominal surgery other than appendectomy or hysterectomy
• Psychiatric comorbidity
• Chronic diseases that will affect the microbiome (cancer, diabetes, cardiovascular disease, liver diseases, neurological diseases, etc.)
• Use of drugs that may affect digestive function in the 4 weeks prior to the study (antibiotics (including use in the last 4 weeks), probiotics, narcotic analgesics, lactulose (prebiotics))
• Patients taking dietary supplements
• Excluded from the study if following a restricted diet.

Individual participant data will be made available in a data repository

This is a double-blinded randomized controlled study. The participants will be blinded to the dietary interventions and the care providers will apply the diets that were allocated to them without knowing which diet they are applying. The investigators will not be able to obtain data until the data collection is finished.