Increasing Symptoms in Irritable Bowel Symptoms With Ingestion of Galacto-Oligosaccharides Are Mitigated by α-Galactosidase Treatment

Am J Gastroenterol. 2018 Jan;113(1):124-134. doi: 10.1038/ajg.2017.245. Epub 2017 Aug 15.


Objectives: Galacto-oligosaccharides (GOS) are dietary FODMAPs (fermentable carbohydrates) associated with triggering gastrointestinal symptoms in patients with irritable bowel syndrome (IBS). This randomized, double-blind, placebo-controlled, cross-over trial aimed to assess whether oral α-galactosidase co-ingestion with foods high in GOS and low in other FODMAPs would reduce symptoms.

Methods: Patients meeting the Rome III criteria for IBS who were hydrogen-producers on breath testing were recruited. Participants were treated with full-dose (300 GALU (galactosidic units) α-galactosidase) and half-dose enzyme (150 GALU α-galactosidase), and placebo (glucose) in a random order with ≤14 days washout between arms. Following a 3-day low FODMAP run-in period, participants consumed provided diets high in GOS for a further 3-days. Gastrointestinal symptoms were measured daily using a 100 mm visual-analogue-scale, and breath samples taken hourly on the second last day with hydrogen content analysed as area-under-the-curve.

Results: Thirty-one patients with IBS (20 IBS-D, 4 IBS-C, 7 IBS-M) completed the study. The addition of high GOS foods resulted in a significant increase in overall symptoms with 21 patients exhibiting GOS-sensitivity (>10 mm increase for overall symptoms). Of those, full-dose enzyme reduced overall symptoms (median 24. 5(IQR 17.5-35.8) vs. 5.5(1.5-15.0) mm; P=0.006) and bloating (20.5(9.5-42.0) vs. 6.5(2.0-15.8); P=0.017). Breath hydrogen production was minimal with no differences seen between placebo and full-dose (P=0.597).

Conclusions: Oral α-galactosidase taken with high GOS foods provides a clinically significant reduction in symptoms in GOS-sensitive individuals with IBS. This strategy can be translated into practice to improve tolerance to high GOS foods as an adjunct therapy to the low FODMAP diet.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Breath Tests
  • Cross-Over Studies
  • Dietary Carbohydrates / adverse effects*
  • Disease Progression
  • Double-Blind Method
  • Female
  • Galactose / adverse effects*
  • Humans
  • Irritable Bowel Syndrome / chemically induced
  • Irritable Bowel Syndrome / drug therapy*
  • Irritable Bowel Syndrome / physiopathology
  • Male
  • Middle Aged
  • Oligosaccharides / adverse effects*
  • Young Adult
  • alpha-Galactosidase / therapeutic use*


  • Dietary Carbohydrates
  • Oligosaccharides
  • alpha-Galactosidase
  • Galactose