Assessing Impact of Individual FODMAPs on IBS Symptom Severity

Man suffering stomach ache sitting on a couch in the living room at home
Researchers analyzed the effects of individual FODMAPs on symptom severity in patients with IBS.

The following article is a part of conference coverage from the Digestive Disease Week 2021 Annual Meeting , held virtually from May 21 to 23, 2021. The team at Gastroenterology Advisor will be reporting on the latest news and research conducted by leading experts in gastroenterology. Check back for more from DDW 2021.


Reintroduction of fructans and galactans following an elimination diet was associated with worsening of gastrointestinal symptoms in irritable bowel syndrome (IBS), according to study data presented at Digestive Disease Week (DDW) 2021.

While prior research suggests that a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) may ameliorate the symptoms of IBS, the relative impact of each specific FODMAP remains unclear. To determine whether individual FODMAPs are equally likely to affect symptom severity in IBS, investigators conducted a 12-week crossover study.

Patients with IBS underwent a 2-4 week open-label FODMAP elimination period under the supervision of a dietician. Clinical response was defined as a ≥40% improvement in abdominal pain from baseline. Clinical responders were then randomized to 1 of 5 reintroduction sequences: 7 days of either a fructan-, fructose-, galactan-, lactose-, or polyol-containing brownie. Randomization was double-blind.

After completing 1 reintroduction sequence, patients entered a 7-day washout period before initiating another reintroduction sequence. Patients completed all reintroduction sequences, for a total of 10 weeks of FODMAP reintroduction. Abdominal pain and bloating scores were monitored throughout the trial. Linear mixed effects models were used to characterize the relationship between individual FODMAPs and gastrointestinal symptoms.

A total of 45 patients were enrolled in the trial between 2018 and 2020. Of these, 25 experienced symptom improvement with the elimination diet. Twenty patients continued to the reintroduction phase, among whom 100% completed the full study.

Per linear mixed effects models, abdominal pain was worse with the fructan challenge (P =.007), irrespective of sequence of FODMAP reintroduction. Abdominal pain also increased over study duration independent of reintroduction sequence (P =.006). In analyses restricted to the first reintroduction period, the fructan (P =.03) and galactan (P =.04) challenges were significantly associated with abdominal pain, while other reintroduction challenges were not. Bloating also worsened as study period increased (P =.002). In analyses restricted to first reintroduction challenge, galactan (P =.03) was significantly associated with bloating.

Per these results, fructans and galactans may be more significant IBS triggers than other FODMAPs. “These findings suggest that all FODMAPs are not equal and [opens] the door to trials evaluating the clinical benefits of a simplified low FODMAP diet in IBS patients,” investigators wrote.

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Eswaran SL, Singh P, Rifkin S, Chey WD. Are all FODMAPs created equal? a blinded, randomized reintroduction trial to determine which FODMAPs drive clinical response in IBS patients. Poster presented at: Digestive Disease Week Annual Meeting; May 21-23, 2021. Abstract Su576.