Clinical application of dietary therapies in irritable bowel syndrome

Diet appears to play a pivotal role in symptom generation in Irritable Bowel Syndrome (IBS). First line dietary therapy for IBS has focused on advice concerning healthy eating and lifestyle management. Research recently has focused on the role of a diet low in fermentable oligo-, di-, and mono-saccharides and polyols (FODMAPs), gluten free (GFD) and wheat free (WFD) diets for the relief of symptoms in IBS.

A round table discussion with gastroenterologists and dietitians with a specialist interest in dietary therapies in IBS was held in Sheffield, United Kingdom in May 2017. Existing literature was reviewed. PubMed and EMBASE were searched with the MeSH terms irritable bowel syndrome/diet/diet therapy/gluten/low FODMAP in different combinations to identify relevant articles. A consensus on the application of these dietary therapies into day-to-day practice was developed.

Fourteen randomized trials in IBS evaluating the low FODMAP diet (n studies = 9), GFD (n = 4) and WFD (n = 1) were included in this review. The total number of patients recruited from randomized trials reviewed was: n=580 low FODMAP diet (female, n=430), n=203 GFD (female, n=139), n=276 WFD (female, n=215). There was no significant difference in the gender of patients recruited for both the low FODMAP and GFD randomized studies (p=0.12). The response rate in the literature to a low FODMAP diet ranged between 50-76%, and to GFD ranged between 34-71%. Percentage of IBS patients identified as wheat sensitive was reported as 30% in the literature.

There are no head-to-head trials to date utilizing the low FODMAP diet, GFD and WFD for dietary treatment of IBS and still a number of concerns for diets, including nutritional inadequacy and alteration of the gut microbiota. The consensus suggests that there is evidence for the use of the low FODMAP diet, GFD and WFD as dietary therapies for IBS; the decision-making process for using each individual therapy should be directed by a detailed history by the dietitian, involving the patient in the process.