Review
The low-FODMAP diet for irritable bowel syndrome: Lights and shadowsDieta con bajo contenido en FODMAP para el síndrome del intestino irritable: luces y sombras

https://doi.org/10.1016/j.gastrohep.2015.07.009Get rights and content

Abstract

Irritable bowel syndrome (IBS) affects 10–15% of the western population. Drug therapy for this entity has shown limited efficacy. The low Fermentable Oligo-, Di-, Monosaccharides And Polyols (FODMAP) diet has recently emerged as an effective intervention for reducing gastrointestinal symptoms in IBS. Currently, several mechanistic studies have proven the rational basis of carbohydrate restriction. In addition, high-quality evidence (prospective studies and randomized controlled trials) from a variety of countries supports the high effectiveness of a low-FODMAP diet for IBS symptoms (70%), especially abdominal bloating, pain, and diarrhea. Importantly, this diet seems to be superior to a gluten-free diet for patients with non-celiac gluten sensitivity. The most controversial features of the low FODMAP diet are its short- and long-term limitations (a high level of restriction, the need for monitoring by an expert dietitian, potential nutritional deficiencies, significant gut microbiota reduction, lack of predictors of response), as well as the potential lack of advantage over alternative dietary, pharmacological and psychological interventions for IBS. Although liberalization of carbohydrate intake is recommended in the long-term, the reintroduction process remains to be clarified as, theoretically, global carbohydrate restriction is deemed to be necessary to avoid additive effects.

Resumen

El síndrome de intestino irritable (SII) es una entidad clínica que afecta al 10-15% de la población occidental, para la que los fármacos disponibles han demostrado una eficacia limitada. La dieta con bajo contenido en oligo, di, monosacáridos y polioles (FODMAP) ha surgido recientemente como una medida eficaz para el control de los síntomas gastrointestinales del SII. En la actualidad, los estudios fisiopatológicos han confirmado la base racional de la restricción de carbohidratos en el SII y existe evidencia científica de alta calidad (estudios prospectivos y ensayos clínicos controlados) proveniente de diversos países confirmado la eficacia de la dieta con bajo contenido en FODMAP para el SII (70%), especialmente para la hinchazón y dolor abdominal, así como la diarrea. Cabe destacar que esta dieta parece ser más eficaz que la dieta sin gluten para los pacientes con sensibilidad al gluten no celíaca. Los aspectos más controvertidos de esta dieta son las limitaciones que implica a corto y largo plazo (nivel alto de restricción alimentaria, la necesidad de monitorización por dietistas, riesgo de déficits nutricionales, una descenso marcado de la microbiota intestinal, la ausencia de herramientas predictoras de respuesta), al igual que una eficacia similar a otras intervenciones dietéticas menos restrictivas, farmacológicas y psicológicas en recientes estudios. Pese a que se recomienda liberalizar el consumo de carbohidratos a largo plazo, queda por dilucidar con exactitud la estrategia de reintroducción, ya que teóricamente el éxito de la dieta reside en una restricción global de carbohidratos para evitar efectos aditivos.

Introduction

Irritable bowel syndrome (IBS) affects 10–20% of individuals worldwide.1 The condition is characterized by chronic abdominal pain associated with disordered defecation or a change in bowel habit.2 IBS has a considerable effect on quality of life and people with IBS spend more days in bed, miss more work days, have more consultations with their primary care physician than those without the condition, besides social functioning is even worse in IBS than in other chronic diseases such as diabetes.3 Furthermore, the chronic nature of IBS, its high prevalence and its associated comorbidities contribute to a considerable economic burden on health-care services.4, 5

The pathophysiology of IBS is complex and multifactorial, including altered gastrointestinal motility, increased gastrointestinal fermentation, abnormal gas transit, visceral hypersensitivity, brain – gut axis dysregulation, dysbiosis of the gut microbiota, genetic predisposition and psychosocial aspects.6 Treatment of IBS has historically been symptom-directed (e.g., bulking agents, antispasmodic agents) or centrally acting (e.g., antidepressants, cognitive–behavioral therapy), but the efficacy of these treatments is limited.

Many patients believe that their IBS symptoms are diet-related,7 but evidence supporting the effect of dietary intervention on IBS symptoms has been of limited quality. A controversial study on the efficacy of a tailored therapy for IBS, based on serum IgG levels to foods, definitely set off this line of thinking in 2004.8 The authors suggested a 3-month diet based on IgG results was significantly more effective for IBS symptoms than a sham diet, excluding the same number of foods, but not those to which they had antibodies. This study was much contested due to design and methodological flaws that questioned their conclusion, since the treatment group excluded significantly more different foods than the control group, particularly those foods which appear to exacerbate symptoms of IBS.9, 10 As such, differences between diets could largely be explained not by specific identification of food reactions by IgG testing, but rather by the gross differences between the two diets. This questionable study, however, proved dietary restriction was effective for IBS and paved way for a growing interest in dietary approaches for the management of IBS among both clinicians and patients.11

Section snippets

The FODMAP concept

In parallel with the rising incidence for gastrointestinal diseases (IBS, inflammatory bowel disease or celiac disease) over the past two decades, patterns of food intake and dietary behavior have dramatically changed worldwide. Fructose consumption has increased fourfold in children <10 years old and around 20% in general population. Caloric sweeteners are commonly used for beverages, intake of fast food (pizza, hamburgers, snacks, beverages) and wheat-containing foods (pasta, bread, cakes)

FODMAPs in the diet

The content of FODMAPs in the diet varies across geographical areas due to variable doses delivered in the diet, the most common being fructose and fructans.22 For instance, consumption of fructans/galacto-oligosaccharides (GOS) is higher in the Mediterranean countries due to increased bread and legume intake. High FODMAP food sources (where FODMAPs are problematic based on standard serving size) and suitable low FODMAP alternatives, according to food analysis conducted in Australian foods,23,

Pathophysiological rationale for low FODMAP diet

The rationale behind using low FODMAP diet is that a reduction of the detrimental gastrointestinal effects of non-absorbed carbohydrates, mainly increase in luminal water content and bacterial fermentation, will likely improve symptoms in IBS patients.21, 22 After FODMAP ingestion, increased delivery of water to the small intestine (measured by magnetic resonance imaging)34, 35 and the proximal colon (ileal effluent in ileostomates patients),19 due to their osmotic effects, have been

The efficacy of low FODMAP diet for irritable bowel syndrome

A number of clinical uncontrolled studies from Australia, New Zealand, Norway, United Kingdom, Denmark and Spain15, 46, 47, 48, 49, 50, 51 have consistently shown the efficacy of low FODMAP diet for IBS. Solid evidence supporting the efficacy of low FODMAP diet relies on five controlled trials, four of these being randomized controlled trials (RCT) (Table 2).20, 52, 53, 54, 55 The non-RCT compared low FODMAP diet to standard dietary advice for IBS, according to recommendations from The National

The efficacy of low FODMAP diet for non-celiac gluten sensitivity

Non-celiac gluten sensivity (NCGS) is an emerging disorder characterized by intestinal and extraintestinal symptoms related to the ingestion of gluten-containing food, in patients who are not affected by either celiac disease or wheat allergy. Due to the absence of reliable biomarkers, NCGS remains a diagnosis of exclusion of celiac disease and most patients are self-diagnosed and voluntarily start a gluten-free diet (GFD).57 A recent systematic review on NCGS has highlighted the lack of

Criticisms to low FODMAP diet

It is clear that IBS treatments are unsatisfactory in many cases. This is related to different aspects, ranging from the complex and incompletely understood pathophysiology of IBS to its enormous clinical heterogeneity. Moreover, some IBS medications (received with great expectations) had to be withdrawn from the market because of side effects.66 New promising drugs have been launched, and some others will be in the next future, but its final place in the treatment algorithm of IBS in the

Conflict of interest

The authors declare no conflict of interest.

Acknowledgements

We kindly appreciate the comments provided by Dr. Peter Gibson and his team from the Monash University in Australia.

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