Long-term personalized low FODMAP diet improves symptoms and maintains luminal Bifidobacteria abundance in irritable bowel syndrome

Background: 
Short-term trials demonstrate the low FODMAP diet improves symptoms of irritable bowel syndrome (IBS) but impacts nutrient intake and the gastrointestinal microbiota. The aim of thisstudy was to investigate clinical symptoms, nutrient intake and microbiota of patients with IBS 12 months after starting a low FODMAP diet. 
Methods: 
Participants enrolled in a previous short-term clinical trial and who had been through structured FODMAP restriction, reintroduction and personalisation were invited to participate in a follow-up study at one time point at 12 months. Gastrointestinal symptoms, stool output, dietary intake and quality of life were recorded. Stool samples were collected and analysed for microbiota (qPCR) and short-chain fatty acids (SCFA). Data were compared with baseline (prior to any intervention in the original clinical trial) using non-parametric statistics.
Key results: 
Eighteen participants were included in the study. Adequate relief of symptoms occurred in 5/18 (28%) at baseline and increased to 12/18 (67%) following long-term personalised low FODMAP diet (p=0.039). There was a reduction in IBS-SSS total score between baseline (median 227, IQR 99)and long term (154, 89; p<0.001). Bifidobacteria abundance was not different between baseline (median 9.29, IQR 1.45) and long term (9.20, 1.41; p=0.766, q=0.906), however there were lower concentrations of total SCFA, acetate, propionate and butyrate.
Conclusions: 
In this long-term analysis, two thirds of patients reported adequate relief of symptoms after 12 months of personalised low FODMAP diet, that did not result in differences from baseline inBifidobacteria. FODMAP reintroduction and personalisation may normalise some of the effects of short-term FODMAP restriction.