Dietary Interventions for Irritable Bowel Syndrome

This interventional, parallel‐group study was conducted at the GastroenterologyOutpatient Clinic of Mersin University Hospital between February 25 and July 18, 2025.The study included adults aged 19‐64 years who had been diagnosed with irritable bowelsyndrome, met the eligibility criteria, provided written informed consent, and agreed tofollow the assigned dietary intervention.Participants followed either a low‐FODMAP diet or a combined gluten‐free and lactose‐freediet for six weeks. The low‐FODMAP intervention restricted foods high in fermentableoligosaccharides, disaccharides, monosaccharides, and polyols. The combined gluten‐freeand lactose‐free intervention excluded foods containing gluten and lactose. Participantsreceived detailed dietary instructions during the initial face‐to‐face visit.At baseline, a researcher administered a data collection form covering sociodemographiccharacteristics, health information, dietary habits, and food preparation and cookingpractices. Gastrointestinal symptom severity was measured using the Irritable BowelSyndrome Symptom Severity Score (IBS‐SSS). The IBS‐SSS produces a total score rangingfrom 0 to 500, with higher scores indicating greater symptom severity. It assessesabdominal pain severity, frequency of abdominal pain, abdominal bloating, satisfactionwith bowel habits, and the interference of bowel symptoms with daily life.Participants were contacted by telephone one week after starting the diet andsubsequently at two‐week intervals to monitor adherence. At the end of the six‐weekintervention, the IBS‐SSS was administered again during a face‐to‐face visit. The primaryanalysis evaluated the change in IBS‐SSS total score from baseline to week 6 and comparedsymptom changes between the two dietary intervention groups.