The low FODMAP diet: recent advances in understanding its mechanisms and efficacy in IBS

Abstract

There is an intensifying interest in the interaction between diet and the functional GI symptoms experienced in IBS. Recent studies have used MRI to demonstrate that short-chain fermentable carbohydrates increase small intestinal water volume and colonic gas production that, in those with visceral hypersensitivity, induces functional GI symptoms. Dietary restriction of short-chain fermentable carbohydrates (the low fermentable oligosaccharide, disaccharide, monosaccharide and polyol (FODMAP) diet) is now increasingly used in the clinical setting. Initial research evaluating the efficacy of the low FODMAP diet was limited by retrospective study design and lack of comparator groups, but more recently well-designed clinical trials have been published. There are currently at least 10 randomised controlled trials or randomised comparative trials showing the low FODMAP diet leads to clinical response in 50%-80% of patients with IBS, in particular with improvements in bloating, flatulence, diarrhoea and global symptoms. However, in conjunction with the beneficial clinical impact, recent studies have also demonstrated that the low FODMAP diet leads to profound changes in the microbiota and metabolome, the duration and clinical relevance of which are as yet unknown. This review aims to present recent advances in the understanding of the mechanisms by which the low FODMAP diet impacts on symptoms in IBS, recent evidence for its efficacy, current findings regarding the consequences of the diet on the microbiome and recommendations for areas for future research.

Content of Poorly Absorbed Short‐Chain Carbohydrates (FODMAP) in Enteral Homemade Diets

“…In contrast, individuals with digestive impairment and problems with the absorption of these carbohydrates frequently exhibit intolerance to foods rich in FODMAP, presenting abdominal distension, colic, and diarrhea, among other intestinal symptoms, which affect their quality of life . In this way, the blenderized whole‐food enteral diet, which has a low FODMAP content, offers an effective approach in the management of patients receiving ENT who have functional intestinal symptoms …”

Dietary therapies for functional bowel symptoms: Recent advances, challenges, and future directions

“…The low FODMAP diet is one of the most extensively studied diets for FBD, with multiple randomized controlled trials conducted worldwide . These studies suggest improvement in 50%‐81% of patients with IBS but this magnitude of benefit has been questioned for a number of reasons. The studies have been criticized due to small subject numbers, potential for unblinding, and the possibility for placebo response to influence the reported response rates .…”

“…Following the low FODMAP diet, reductions have been seen in total fecal SCFAs and specific types including Butyrate, a SCFA thought to have protective health effects . However, data on whether significant changes in SCFA's occur are conflicting possibility related to small subject numbers and differences in methodology used.…”

Dietary Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols (FODMAPs) and Gastrointestinal Disease

“…Studies in healthy individuals and patients with irritable bowel syndrome using magnetic resonance imaging show a significant increase in colonic gas with high FODMAP diets. In patients with irritable bowel syndrome, the increased gas is associated with the development of abdominal symptoms . Studies using magnetic resonance imaging show that polysaccharides such as inulin commonly derived from plant products such as chicory root increase colonic gas in both healthy individuals and patients with irritable bowel syndrome and are associated with symptoms in patients with irritable bowel syndrome .…”