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FODMAPs and Symptoms in Patients With Irritable Bowel Syndrome
abstract
This abstract is available on the publisher's site.
Access this abstract nowOBJECTIVE
To gain mechanistic insights, we compared effects of low fermentable oligosaccharides, disaccharides and monosaccharides and polyols (FODMAP) and high FODMAP diets on symptoms, the metabolome and the microbiome of patients with IBS.
DESIGN
We performed a controlled, single blind study of patients with IBS (Rome III criteria) randomised to a low (n=20) or high (n=20) FODMAP diet for 3 weeks. Symptoms were assessed using the IBS symptom severity scoring (IBS-SSS). The metabolome was evaluated using the lactulose breath test (LBT) and metabolic profiling in urine using mass spectrometry. Stool microbiota composition was analysed by 16S rRNA gene profiling.
RESULTS
Thirty-seven patients (19 low FODMAP; 18 high FODMAP) completed the 3-week diet. The IBS-SSS was reduced in the low FODMAP diet group (p<0.001) but not the high FODMAP group. LBTs showed a minor decrease in H2 production in the low FODMAP compared with the high FODMAP group. Metabolic profiling of urine showed groups of patients with IBS differed significantly after the diet (p<0.01), with three metabolites (histamine, p-hydroxybenzoic acid, azelaic acid) being primarily responsible for discrimination between the two groups. Histamine, a measure of immune activation, was reduced eightfold in the low FODMAP group (p<0.05). Low FODMAP diet increased Actinobacteria richness and diversity, and high FODMAP diet decreased the relative abundance of bacteria involved in gas consumption.
CONCLUSIONS
IBS symptoms are linked to FODMAP content and associated with alterations in the metabolome. In subsets of patients, FODMAPs modulate histamine levels and the microbiota, both of which could alter symptoms.
Additional Info
Disclosure statements are available on the authors' profiles:
FODMAPs Alter Symptoms and the Metabolome of Patients With IBS: A Randomised Controlled Trial
Gut 2016 Mar 14;[EPub Ahead of Print], K McIntosh, DE Reed, T Schneider, F Dang, AH Keshteli, G De Palma, K Madsen, P Bercik, S VannerFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
The study by McIntosh et al validates that the low FODMAP diet (LFD) provides significant symptom relief when compared to a high FODMAP diet in patients with irritable bowel syndrome (IBS). This study confirms clinical benefits and that the stool microbiome significantly changes after institution of the LFD. Importantly, this study is one of the first to report the downstream metabolic consequences of reduced FODMAP intake and altering the microbiome. The authors identified significant alterations in urinary metabolites, the most notable of which included histamine, p-hydroxybenzoic acid, and azelaic acid. The significant reductions in urine histamine are of particular interest given its relation to mast cells and known effects on gastrointestinal function, sensation, and immune activation. There are significant limitations. The small sample size of 37 patients (19 low FODMAP, 18 high FODMAP) renders it no more than hypothesis generating and makes it impossible to draw any confident conclusions about clinical or translational effects of the LFD in different IBS subgroups. Further, the short study duration (3 weeks) combined with the use of a high FODMAP diet as the comparator reduce the practical value of the clinical portion of the study. Still, this is a very important study if for no other reason than to notch another peg in favor of the efficacy of the LFD and to broaden the discussion of how this diet benefits IBS patients.