Exclude or Expose in Irritable Bowel Syndrome: What Works for Whom and How?

The intervention is an online diet program. The diet is the low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet. It is a 3-phase diet which involves: 1.Phase 1 FODMAP restriction: restrict foods high or moderate in FODMAPs and swap these for low FODMAP alternatives; 2. Phase 2 FODMAP reintroduction: continue to follow a low FODMAP diet and complete a series of food challenges to understand which foods and FODMAPs are tolerated and which trigger symptoms; 3. Phase 3 FODMAP personalization: include well-tolerated foods and FODMAPs back into the diet, and restrict poorly tolerated foods and FODMAPs to a level needed to maintain symptom relief. The online FODMAP program is a self-directed diet program with support from an online clinician (Accredited Practicing Dietitian \[APD\]). The content is delivered over 12 weeks. After each module participants will complete homework activities and questions and submit them to the dietitian for feedback.

The intervention is an online behavioral therapy program. The behavioral therapy is Exposure-based Cognitive Behavioral Therapy (E-CBT) Program. The E-CBT program is organised into six steps to be completed over 12 weekly modules with support from an online clinician (Psychologist). The first step contains a rationale for the treatment and instructions on self-observation. Steps 2, 3 and 4 contain a presentation of a psychological model of IBS and continued self-observation exercises. The fifth step covers exposure exercises, divided into three categories; (1) exercises that provoke symptoms, (2) abolishment of behaviors that serve to control symptoms, (3) exposure to situations where symptoms were unwanted. The final step (Step 6) includes how to handle relapses into avoidance behaviors and how to maintain a widened behavioral repertoire. After each module participants will be directed to complete homework activities and questions and submit them to the psychologist for feedback.