Dietary Interventions and IBS: What Really Works?

Abstract and Introduction

Abstract

Purpose of Review: The review examines the latest research on the use of dietary interventions in the management of irritable bowel syndrome (IBS) in order to understand what is the evidence supporting the efficacy of a dietary approach in this disorder.

Recent Findings: A general dietary advice should be offered to all IBS patients. Psyllium supplementation is recommended in IBS with both constipation and diarrhea predominance. There is increasing evidence showing the beneficial effects of a low fermentable oligo-, di-, monosaccharides, and polyols (FODMAP) diet (LFD) on IBS symptoms. FODMAPs that are well tolerated should be reintroduced in daily diet, to increase acceptability of the diet, and limit potentially harmful effects. The benefits observed with the gluten-free diet seem determined by the reduction of FODMAPs rather than gluten. Modulation of gut microbiota using probiotics shows promising results, but there are unanswered questions regarding the optimal strains, dose and duration of treatment. Additional evidence is also needed for the role of prebiotics and synbiotics in IBS.

Summary: Food is both trigger of IBS symptoms and therapeutic tool. Recent studies demonstrated the beneficial effects of LFD on symptom control, as well as the role of probiotics, which seem to contribute to gut health and function.

Introduction

Irritable bowel syndrome (IBS) is one of the most frequent disorders of brain–gut interaction, characterized by change in bowel habits accompanied by recurrent abdominal pain, in the absence of any detectable structural or biological abnormality of the gastrointestinal tract.^[1] The prevalence in the general population, based on Rome IV criteria, is 4.1% in internet surveys, 1.5% in household surveys, and doubles when using Rome III criteria. Similar proportions of subjects have diarrhea predominant (IBS-D), constipation predominant (IBS-C) or mixed type IBS (IBS-M).^[2]

The etiology of IBS is complex, yet poorly understood. Factors involved in the pathogenesis of IBS may include intestinal dysmotility, low-grade inflammation, visceral hypersensitivity, alterations in intestinal microbiota, genetic predisposition, stress and diet.^[3] Alimentation appears to play an important role, most IBS patients reporting that meals induce or exacerbate symptoms. Osmotic, chemical, mechanical, neuroendocrine, prebiotic, probiotic effects as well as effects related to fermentation by-products are mechanisms by which diet may trigger symptoms in IBS.^[4] Particular interest has been given recently to the interaction between diet, microbiota, and gut endocrine cells in the pathogenesis of IBS, correlated with the fact that the density of gut endocrine cells is low in IBS patients. The mechanism may involve interactions between by-products resulting from bacterial fermentation of foods with gut stem cells resulting in a low rate of differentiation toward endocrine cells and a subsequent diminished secretion of gut hormones. These hormones interact and integrate with the enteric, autonomic, and central nervous systems and regulate gut motility, visceral sensitivity, and secretion. A low enteroendocrine-cell density will therefore generate gut dysmotility, visceral hypersensitivity, and abnormal secretion, which may give rise to symptoms seen in IBS.^[5]

The chronic nature of IBS with recurrent and exacerbating symptoms, negatively impacts quality of life (QoL) and has a marked economic impact on the healthcare system.^[6] Unfortunately, therapeutic progress is slow and results are contradictory. Therefore, one needs more efficient treatment strategies to reduce IBS impact on patients and health budget. In recent years, particular attention has been given to diet as a first-line treatment to improve IBS symptoms.^[3] General dietary advice, the diet low in fermentable oligo-, di-, monosaccharides, and polyols (FODMAPs), the gluten-free diet (GFD), dietary fiber supplementation and interventions that modulate gut microbiota are now promoted in IBS management.