The evidence base for efficacy of the low FODMAP diet in irritable bowel syndrome: is it ready for prime time as a first-line therapy?

Six randomized controlled trials comparing low FODMAP diet with placebo approaches have all indicated efficacy in patients with irritable bowel syndrome (IBS). The studies have provided all the food (n = 3) or utilized dietitian-led education (n = 3). They have variably met criticisms regarding issues such as the choice of placebo, the number of patients studied, the success of blinding, and the duration of the interventions, but the results are uniformly positive for the diet. Real-world experience of the low FODMAP diet has confirmed the findings of the randomized studies, in that about 70% of patients respond. Difficulty in delivering the diet has not been an issue, and the majority of patients find the diet easy to follow when dietitian led. Observational studies have suggested durability of efficacy, even in association with reintroduction of FODMAPs as recommended. Three studies comparing institution of standard dietary guidelines for IBS with the low FODMAP diet have found either similar or improved outcomes with the latter. Low FODMAP diet also has similar efficacy to that of gut-directed hypnotherapy, another strategy with broad benefit in IBS. There are currently no clinically applicable indices that predict response to the diet. In conclusion, clinical trials and observational studies support the notion that a dietitian-led low FODMAP diet is ready for primetime and should be considered as a first-line therapy for patients with IBS where the use of a restrictive diet is appropriate.