Food Choice as a Key Management Strategy for Functional Gastrointestinal Symptoms

INTRODUCTION Th e association of ingestion of food with the induction of gastrointestinal (GI) and, less commonly, non-GI symptoms is widely accepted by the community. In patients with irritable bowel syndrome (IBS), the frequency of perceptions of food intolerance is at least twofold more common than in the population in general ( 1 ). Furthermore, many take actions in accord with their perceptions. For example, in a Norwegian population study, 70 % of 84 patients with IBS had symptoms related to food intake and most of those limited or excluded the perceived foods from their diet ( 2 ). In fact, food choice is the major method that women use to infl uence their symptoms ( 3 ). Th e belief that food is causing or at least triggering gut symptoms has led to the application of a profusion of investigations purporting to guide dietary design (such as skin prick tests, food-specifi c immunoglobulins, and many non-validated tests) ( 4 ), and of dietary therapies (such as gluten-free, wheat-free, anticandidal, carbohydrate-free, and other complex exclusion diets). Th e most profound evidence that ingestion of food itself really does have an important role in triggering symptoms was provided by observations of the eff ects of prolonged fasting, where marked improvement was noted in symptoms ( 5 ). However, recognition of what foods or food components are triggering the symptoms has been diffi cult. Broad diff erences in diet between those with and without functional gut symptoms, as assessed by the Harvard Food Frequency Questionnaire, have not been identifi ed ( 1 ). Specifi c intolerances can be sought from patients ’ observations, but these correlate poorly with specifi c tests such as skin prick test and assessment of food-specifi c circulating antibodies ( 6 ). Even when intestinal provocation tests combined with exclusion diet-rechallenge methodology are performed, only a very small proportion of patients proven to have reactions to specifi c foods ( 7 ). Th e application of a bland exclusion diet (to minimize symptoms) followed by blinded rechallenge of a range of food types has been reported to be highly effi cacious, but such enthusiasm has been dampened by the failure of other groups to reproduce the benefi ts, as well as the intensity and prolonged duration of such methodology ( 8 ). Furthermore, the intensity of dietary restrictions may lead to nutritional inadequacy ( 2 ). Such a scenario leaves gastroenterologists generally to have a defensive role when patients request dietary intervention; while food is an undoubted trigger, recognizing what the specifi c food triggers is diffi cult at best, tests designed to do this have unproven or poor predictive value in their clinical utility, and the resulting diets are oft en overrestrictive with the potential to leave the patient nutritionally compromised (2 ) . Th ere have, however, been some notable exceptions, which include manipulation of dietary fi ber intake ( 9 , 10 ), restricting lactose in those with hypolactasia ( 11 ), to a lesser extent, reduction of fructose intake in association with fructose malabsorption ( 12 ), and more recently, application of the very low carbohydrate diet in those with diarrhea-predominant IBS ( 13 ). Food Choice as a Key Management Strategy for Functional Gastrointestinal Symptoms