The impact of diet and ethnicity on gut microbiota variation in irritable bowel syndrome: A multi‐center study

Abstract Background and Aim The gut microbiota in irritable bowel syndrome (IBS) is known to vary with diet. We aim to (i) analyze the gut microbiota composition of IBS patients from a multi‐ethnic population and (ii) explore the impact of a low FODMAP diet on gastrointestinal symptoms and gut microbiota composition among IBS patients. Methods A multi‐center study of multi‐ethnic Asian patients with IBS was conducted in two phases: (i) an initial cross‐sectional gut microbiota composition study of IBS patients and healthy controls, followed by (ii) a single‐arm 6‐week dietary interventional study of the IBS patients alone, exploring clinical and gut microbiota changes. Results A total of 34 adult IBS patients (IBS sub‐types of IBS‐D 44.1%, IBS‐C 32.4%, and IBS‐M 23.5%) and 15 healthy controls were recruited. A greater abundance of Parabacteroides species with lower levels of bacterial fermenters and short‐chain fatty acids producers were found among IBS patients compared with healthy controls. Age and ethnicity were found to be associated with gut microbiota composition. Following a low FODMAP dietary intervention, symptom and quality of life improvement were observed in 24 (70.6%) IBS patients. Symptom improvement was associated with adherence to the low FODMAP diet (46.7% poor adherence vs 92.9% good adherence, P = 0.014), and gut microbiota patterns, particularly with a greater abundance of Bifidobacterium longum , Anaerotignum propionicum , and Blautia species post‐intervention. Conclusion Gut microbiota variation in multi‐ethnic IBS patients may be related to dietary intake and may be helpful to identify patients who are likely to respond to a low FODMAP diet.