Clinical Response to the Low Fodmap Diet at 12 Months: A Prospective Evaluation of Patients with Irritable Bowel Syndrome

Background: Evidence supports the effectiveness of the low FODMAP diet (LFD) in reducing symptoms of irritable bowel syndrome (IBS) in the short term (3-4 weeks).However, whether this improvement is maintained in the long term has not been comprehensively evaluated.This prospective follow-up study aimed to investigate the impact of LFD advice on symptoms and health-related quality of life (HRQOL) in patients with IBS after 12 months.Methods: Adults fulfilling Rome III criteria for IBS were recruited to a 4-week randomized controlled trial comparing the effect of LFD with placebo dietary advice (sham diet).Ninety-five patients completed the study.All sham patients received LFD advice at the end of the trial.All patients received FODMAP reintroduction advice following 4-8 weeks of dietary restriction.Patients were invited to return for a follow-up visit at 12 months after LFD advice.Validated instruments were used to measure gastrointestinal symptoms (adequate relief, IBS-SSS, GSRS) and HRQOL (IBS-QOL, SF-36).Dietary intake was measured using 7-day food records.Results: At 12 months, 18 patients returned for follow-up (11 females, 61%), and most were classified as diarrhoea-predominant IBS (14, 78%).The proportion of patients reporting adequate relief of symptoms increased between baseline (28%) and 12 months (67%, p= 0.039) and there was a reduction in IBS-SSS score (mean±SD; 253±54pts vs 163±54 pts, p<0.001).At 12 months, there was a reduced severity score and a lower incidence of moderate/severe abdominal pain, borborygmi, bloating and overall symptoms according to the GSRS (p<0.05).Frequency of stools passed per week also reduced between baseline (15±6) and 12 months (12±7 stools, p=0.045).In parallel with these symptom improvements there was an increase in IBS-QOL score (median (IQR); 70 (53-77) vs 85 (69-89), p<0.001), and an improved SF-36 pain score (68 (43-83) vs 80 (58-90), p=0.011).Five patients (28%) no longer met the Rome III IBS criteria at 12 months.Conclusions: This long term prospective follow up study demonstrates that patients receiving LFD advice report a reduction in global symptoms and a lower severity and incidence of symptoms at 12 months.Abdominal pain, borborygmi and bloating are symptoms that appear to especially benefit from the LFD.Larger studies are needed to confirm these findings.