Systemic Exposure of Orally Ingested Fructose is Similar between Fructose‐tolerant and Fructose‐intolerant Functional Gastrointestinal Disorder (FGID) Patients

Background Dietary intolerance to fructose is common (60%) in Functional Gastrointestinal Disorder (FGID) patients, yet poorly characterized and empirically managed. Fructose is postulated to be malabsorbed in fructose‐intolerant FGID patients, resulting in gastrointestinal symptoms when unabsorbed fructose is fermented by gut microbiota to form gases. Malabsorption can be indirectly characterized by gas breath tests (i.e. methane, hydrogen) and measurement of systemically absorbed fructose and its metabolites. However, both methods are typically done independently, and the mechanism leading to fructose intolerance remains poorly understood. Objective We aim to correlate plasma fructose and its metabolites in FGID patients after fructose ingestion in their relation to fructose intolerance. Methods Thirty‐one FGID patients, as defined by Rome III criteria, were enrolled into a randomised crossover study in Switzerland (1). Blood (plasma) were collected at 0, 0.5, 1 and 2 h post‐ingestion of 35g fructose or water. Plasma fructose and its metabolites (glucose, alanine, lactate, glycerate) were quantified via liquid chromatography tandem mass spectrometry. Symptoms were recorded using standardized questionnaires, while breath concentrations of hydrogen and methane were measured via BreathTracker Analyzer. Results Intolerance symptoms correlated positively with hydrogen (r=0.7175) and methane (r=0.6093) breath test over the 2 h period, with fructose‐intolerant patients producing significantly more hydrogen (p = 0.0406) and methane (p=0.0400) than fructose‐tolerant patients. However, intolerance symptoms correlated poorly with systemic exposure (AUC 0–2h ) of fructose (r=−0.0066). AUC 0–2h of fructose and its metabolites (glucose, alanine, lactate, glycerate) were similar between fructose‐tolerant and fructose‐intolerant phenotypes. Conclusion For the first time, our study demonstrated fructose intolerance and its higher levels of gases are not associated with fructose malabsorption. Our findings alluded to the potential role of modulated gut microbiota activity in characterizing the differential fructose fermentation phenotypes. Support or Funding Information Funded by Brain‐Gut Research Group, Bern, Switzerland This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .