Evidence-based Dietary Management of Functional Gastrointestinal Symptoms: The FODMAP Approach
Journal of Gastroenterology and Hepatology
Peter R Gibson, Susan J Shepherd, Feb 22, 2010, J Gastroenterol Hepatol. 2010;25(2):252-258. © 2010 Blackwell Publishing
Background and aim: Functional gastrointestinal symptoms are common and their management is often a difficult clinical problem. The link between food intake and symptom induction is recognized. This review aims to describe the evidence base for restricting rapidly fermentable, short-chain carbohydrates (FODMAPs) in controlling such symptoms.
Methods: The nature of FODMAPs, their mode of action in symptom induction, results of clinical trials and the implementation of the diet are described.
Results: FODMAPs are widespread in the diet and comprise a monosaccharide (fructose), a disaccharide (lactose), oligosaccharides (fructans and galactans), and polyols. Their ingestion increases delivery of readily fermentable substrate and water to the distal small intestine and proximal colon, which are likely to induce luminal distension and induction of functional gut symptoms. The restriction of their intake globally (as opposed to individually) reduces functional gut symptoms, an effect that is durable and can be reversed by their reintroduction into the diet (as shown by a randomized placebo-controlled trial). The diet has a high compliance rate. However it requires expert delivery by a dietitian trained in the diet. Breath hydrogen tests are useful to identify individuals who can completely absorb a load of fructose and lactose so that dietary restriction can be less stringent.
Conclusions: The low FODMAP diet provides an effective approach to the management of patients with functional gut symptoms. The evidence base is now sufficiently strong to recommend its widespread application.
Functional gastrointestinal disorders (FGID) are very common and present as major challenges for clinicians, particularly as pharmaceutical therapies offer little more than mild palliation in the vast majority of patients. The symptoms can markedly interfere with quality of life and rank second in the causes of absence from work or school. While the predominant underlying cause of symptoms appears to reside in the enteric nervous system, manifesting as visceral hypersensitivity and/or motility disturbances, multiple other factors contribute to symptoms generation, including psychological factors and diet. Consequently, treatment has spanned multiple modalities and has involved a variety of health professionals, including medical practitioners, psychologists, hypnotherapists, dietitians and naturopaths, each bringing a different perspective. A major limitation has been the limited evidence base for many therapies, not helped by the considerable placebo response seen in these disorders. However, dietary therapy, specifically the low FODMAP diet (see below for explanation), has now emerged as a key player with a well-substantiated mechanism of action and evidence-based efficacy. This review will describe the theoretical basis for the diet, the evidence for efficacy and its implementation, and it will address unanswered questions.