About half of patients with diarrhea-predominant irritable bowel syndrome had adequate symptom relief on either a low FODMAP diet or traditional IBS dietary advice, according to results from a randomized controlled trial.
However, patients in the low FODMAP group had significantly better improvement in individual IBS symptoms, especially pain and bloating.
“This is the first study in American patients, and the largest study looking at the low FODMAP diet in IBS patients so far,” Shanti L. Eswaran, MD, from the division of gastroenterology at University of Michigan Health System, Ann Arbor, told Healio Gastroenterology. “While there was no significant incremental advantage of the low FODMAP diet for global IBS symptoms compared to usual dietary recommendations for IBS, there was a significant benefit for the notoriously difficult to treat IBS symptoms of abdominal pain and bloating.”
Shanti L. Eswaran
William D. Chey
After a 2-week screening period, Eswaran and colleagues — including William D. Chey, MD — identified 92 eligible patients with IBS-D (71% women; median age, 42.6 years; 74% white) who had an average daily abdominal pain score of at least four out of 11 and an average daily stool consistency score of at least 5 on the Bristol Stool Form Scale.
They randomly assigned patients to adhere to a dietician-guided low FODMAP diet or a diet based on modified guidelines from the National Institute for Health and Care Excellence (mNICE) for 4 weeks. Investigators and patients were masked to which diet patients were randomly assigned.
Adequate global symptom relief for at least half of the time during the last 2 weeks served as the primary endpoint. Secondary endpoints included the FDA composite endpoint of at least a 30% reduction in mean daily abdominal pain scores and at least a one-point mean reduction in the daily Bristol Stool Form Scale (BSFS) for any 2 weeks of the study period, as well as individual symptoms.
Of the 45 patients in the low FODMAP group and the 39 patients in the mNICE group who completed the trial, statistically comparable proportions achieved the primary endpoint (52% vs. 41%). A higher proportion of the low FODMAP group achieved the FDA composite endpoint (27% vs. 13%), but this was also not a statistically significant difference.
However, patients on the low FODMAP diet were significantly more likely to report at least a 30% reduction in mean abdominal pain scores (51% vs. 23%; P = .008). In addition, 42% of patients in the low FODMAP diet group had improved stool consistency (at least a 1-point decrease in BSFS scores from baseline) compared with 28% of the mNICE group (P = .18).
Finally, the low FODMAP group had significant individual improvements in abdominal pain, bloating, stool consistency, stool frequency and urgency by the end of the first week, which persisted throughout the study. Conversely, abdominal pain, bloating and stool frequency did not significantly improve in the mNICE group, although stool consistency and urgency did improve modestly.
Both diets were generally well tolerated.
“This study will allow physicians to better inform their patients about likely benefits of the diet,” Eswaran said. “The next steps for this research include delving in to the mechanism by which FODMAP restriction improves symptoms, and determining which FODMAPs are truly responsible for causing symptoms related to IBS.” – by Adam Leitenberger
Disclosures: Chey reports he is a consultant for and received grant funding from Nestle.