Possible Mechanisms Underlying the Effects of Fecal Microbiota Transplantation in Patients With Irritable Bowel Syndrome.

Per AGA best practice advice: dietary intervention is most appropriate for IBS patients who have insight into meal-related symptoms and are motivated to make dietary changes. Soluble fiber (e.g., psyllium/ispaghula) is efficacious for global IBS symptoms and is a reasonable initial option, most suitable in constipation-predominant IBS; insoluble fiber (wheat bran) is NOT. The low-FODMAP diet is currently the most evidence-based diet intervention for IBS and is delivered as a structured 3-phase protocol, NOT lifelong restriction: (1) restriction of high-FODMAP foods lasting NO MORE than 4-6 weeks, (2) reintroduction of FODMAP foods, and (3) personalization based on reintroduction results. Any specific diet intervention should be attempted for a predetermined length of time; if there is no clinical response, the diet should be ABANDONED and a different diet or therapy tried, rather than continued indefinitely. Refer willing and appropriate patients to a GI registered dietitian nutritionist (RDN) to implement and supervise the diet. Poor candidates for restrictive diet interventions include patients who already consume few culprit foods, those at risk for malnutrition, those who are food insecure, and those with an eating disorder or uncontrolled psychiatric disorder; routine screening for disordered eating/eating disorders by careful dietary history is critical before starting a restrictive diet.