Dietary Proteins and Functional Gastrointestinal Disorders

Erica Boettcher MD; Sheila E Crowe MD

Disclosures

Am J Gastroenterol. 2013;108(5):728-736. 

In This Article

Abstract and Introduction

Abstract

Food intolerance is a common complaint amongst patients with functional gastrointestinal (GI) disorders (FGIDs), including those with irritable bowel syndrome (IBS), functional dyspepsia, as well as gastroesophageal reflux disease. Although there has been a longstanding interest in the possible role of food allergy in IBS, there are limited data supporting the association. However, the prevalence of food allergy is sufficiently high that patients with FGID may also have food allergies or hypersensitivities. Food intolerances or sensitivities are reactions to foods, which are not due to immunological mechanisms. Lactose intolerance is common in the general population and can mimic symptoms of FGID or coexist with FGID. As discussed in other articles in this series, other carbohydrate intolerances may be responsible for symptom generation in patients with IBS and perhaps other FGIDs. There is a great interest in the role of a major dietary protein, gluten, in the production of symptoms that are very similar to those of patients with celiac disease without the enteropathy that characterizes celiac disease. Emerging research into a syndrome known as nonceliac gluten sensitivity suggests a heterogeneous condition with some features of celiac disease but often categorized as FGIDs, including IBS. This article summarizes the role of dietary proteins in the symptoms and pathophysiology of FGIDs.

Introduction

Conventional therapies for functional gastrointestinal (GI) disorders (FGID) have mainly focused on relief of symptoms, such as pain, diarrhea, and constipation. Many patients with FGID believe that specific foods or dietary components have a key role in inducing symptoms, but the mechanisms for food-specific GI symptoms are not well elucidated.

A number of observations support a role for food intake in the pathogenesis of FGID symptoms, both in the irritable bowel syndrome (IBS) and functional dyspepsia. The majority of patients report that food intake induces symptoms.[1,2] Many patients report problems with specific foods, and a myriad of dietary interventions have been proposed as therapeutic approaches in alleviating patients' symptoms.[3–6] Although these observations suggest a role of diet in the pathogenesis and treatment of FGID symptoms, the underlying mechanisms for food-specific intolerances or sensitivities are poorly understood and well-conducted, high-quality studies are lacking.

Any abnormal reaction resulting from the ingestion of a food is considered an adverse food reaction (see Figure 1). Such reactions may be the result of food allergies or food sensitivities, or intolerances. Food allergies are adverse health effects that arise from specific immune responses occurring reproducibly on exposure to a specific food.[7] Foods or food components that elicit an adverse reaction but have no established immunologic mechanism are termed food sensitivities.

Figure 1.

Categorization of adverse reactions to food. Any abnormal reaction resulting from the ingestion of a food is considered an adverse food reaction. Such reactions may be immune-mediated, termed food allergy, or nonimmune mediated, termed food sensitivity or food intolerance. The term food allergy comprises clinical conditions associated with altered immunologic reactivity that may be IgE-mediated or non-IgE-mediated. Examples of IgE-mediated responses include oral allergy syndrome (OAS), hives, and anaphylaxis. Among the non-IgE-mediated responses are food protein-induced enterocolitis syndrome (FPIES), eosinophilic esophagitis (EoE), and eosinophilic gastroenteritis, as well as celiac disease. Foods or food components that elicit an adverse reaction but have no established immunologic mechanism are termed food sensitivities. Among the mechanisms for food sensitivity are food toxicity, as well as pharmacological, metabolic, physiological, and psychological food sensitivities. Modified from NIAID-Sponsored Expert Panel.7

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