Fructose malabsorption, symptom severity, IBS subtype predict response to low FODMAP diet

Irritable bowel syndrome patients experienced greater benefits from a low FODMAP diet if they had a positive fructose breath test, greater symptom severity at baseline, and a mixed IBS subtype, according to data presented at the British Society of Gastroenterology Annual Meeting.

“Hydrogen breath testing can identify those with poor absorption of lactose or fructose, who may therefore benefit more from their dietary exclusion as part of the low FODMAP diet,” Anna Cox, BSc, from University College Hospital in London, told Healio Gastroenterology.

Anna Cox

Cox and colleagues sought to determine whether a hydrogen breath test for lactose and fructose intolerance would identify responders to a low FODMAP diet, and also whether patients with diarrhea-predominant IBS (IBS-D) would experience greater improvement compared with constipation-predominant IBS (IBS-C) or mixed IBS (IBS-M) subtypes.

At baseline and a mean of 61 days after treatment, they evaluated IBS symptom severity scores ranging from 0 to 500 based on pain, bloating, constipation and diarrhea in 228 consecutive IBS patients who completed low FODMAP dietary education therapy. Forty-five percent had IBS-D, 33% had IBS-C and 22% had IBS-M, most of whom were women.

Moreover, patients underwent hydrogen breath testing with 30 g fructose and 30 g lactose and were blinded to breath test results until follow-up. Thirty-six percent had positive lactose breath tests, 35% had positive fructose breath tests, and 17% were positive for both.

All patients experienced improvement in symptom severity (–36; P < .001) and 31% were considered responders with more than 50-point improvements.

IBS-M patients experienced greater symptom improvement (–56; P < .001) compared with IBS-D (–37) and IBS-C patients (–29).

A positive fructose hydrogen breath test predicted the greatest response compared with a test negative for both fructose and lactose (–47 vs. –33; P = .008). There were no significant associations observed with tests positive for lactose or both lactose and fructose.

Finally, the researchers found that response mildly correlated with symptom severity at baseline (P = .002), but this relationship was not responsible for differences in response between breath test and IBS subtype groups.

“We found that a positive fructose [breath test], seen in about one-third of IBS patients, predicted a greater response to the low FODMAPs diet, while no association was found for lactose. This suggests that fructose intolerance is an important aspect of FODMAP sensitivity and that fructose breath testing may be useful clinically, both to identify potential responders and to inform re-introduction of fructose following the full low FODMAP elimination period,” Cox said. “We also observed the greatest response in the mixed IBS subtype and in those with diarrhea more than constipation. This is likely due to a reduction in fiber intake with the low FODMAP diet and the subsequent lack of fiber’s laxating effects.” – by Adam Leitenberger

Reference:

Cox A, et al. Abstract #OC-022. Presented at: British Society of Gastroenterology Annual Meeting; June 20-23, 2016; Liverpool, UK.

Disclosures: The researchers report no relevant financial disclosures.

Editor's note: This article was updated on June 22 with additional data and comments from the presenter.