Alterations in the Composition of the Gut Microbiota in Celiac Disease, Non-Coeliac Gluten Sensitivity and Irritable Bowel Syndrome

Background and aims: Some chronic intestinal disorders, including irritable bowel syndrome (IBS), coeliac disease (CD), and non-coeliac gluten sensitivity (NCGS), can make some changes to the gut microbiota composition and cause dysbiosis. This study aimed to determine the gut microbiota alterations in CD, NCGS, and IBS patients among the Iranian population compared to healthy controls.Materials and Methods: In this prospective study, 72 patients, including 15 healthy controls (HC), 30 IBS, 12 NCGS, and 15 CD patients were included. IBS, CD, and NCGS were diagnosed based on the Rome IV diagnostic criteria, Modified Marsh classification, and gluten challenge test. Stool samples were collected from patients, and after DNA extraction, quantitative real-time PCR (qPCR) was performed for assessing the relative abundance of Firmicutes, Bacteroidetes, Bifidobacterium spp., and Lactobacillus spp. Results: Firmicutes and Lactobacillus spp. were the most and the least abundant phylum in all samples, respectively. In CD patients, Firmicutes phylum was the most significant relative abundance. Bacteroidetes phylum had a significant relative abundance in CD (P<0.01) and NCGS (P<0.05) patients. The relative abundance of Bifidobacterium spp. was statistically lower in CD (P<0.05) and IBS patients (P<0.001) compared to the HCs. The Firmicutes to Bacteroidetes ratio was statistically significant in NCGS and CD patients compared to the HCs (P = 0.05).Conclusion: Chronic intestinal diseases, including IBS, CD, and NCGS, can alter the gut microbiota composition.