Low fermentable oligosaccharide, disaccharide, monosaccharide, and polyol diet in patients with diarrhea-predominant irritable bowel syndrome: A prospective, randomized trial

J Gastroenterol Hepatol. 2021 Aug;36(8):2107-2115. doi: 10.1111/jgh.15410. Epub 2021 Feb 4.


Background and aim: Low fermentable oligosaccharide, disaccharide, monosaccharide, and polyol (FODMAP) diet improves irritable bowel syndrome (IBS) symptoms. Data on long-term "modified" FODMAP diet are emerging. We aimed to assess efficacy and acceptability of short-term "strict" low FODMAP diet (LFD) and long-term "modified" FODMAP diet in patients with diarrhea-predominant IBS (IBS-D).

Methods: This prospective randomized trial included patients with IBS-D (Rome IV) and IBS severity scoring system (IBS-SSS) ≥ 175. In phase I (4 weeks), patients were randomized to strict LFD and traditional dietary advice (TDA) groups. From 4 to 16 weeks, LFD group was advised systematic reintroduction of FODMAPs ("modified" FODMAP diet). Response was defined as > 50-point reduction in IBS-SSS.

Results: Of the total 166 patients with IBS-D screened, 101 (mean age 41.9 ± 17.1 years, 58% male) were randomized to LFD (n = 52) and TDA (n = 49) groups. Both at 4 and 16 weeks, total IBS-SSS and IBS quality of life score reduced significantly in both groups, but there was significantly greater reduction in LFD group. By intention-to-treat analysis, responders in LFD group were significantly higher than TDA group (4 weeks-62.7% [32/51] vs 40.8% [20/49], respectively, P = 0.0448; 16 weeks-52.9% [27/51] vs 30.6% [15/49], respectively; P = 0.0274). Compliance to LFD was 93% at 4 weeks and 64% at 16 weeks. Energy, carbohydrate, fat, and fiber intake showed reduction in LFD group at 4 weeks, which improved till 16 weeks.

Conclusions: Strict LFD for short-term and "modified" LFD for long term in IBS-D patients is acceptable and leads to significant improvement in symptoms and quality of life.

Keywords: Abdominal pain; Colon; FODMAP; Food; Gastrointestinal; Nutrition.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Diarrhea / etiology
  • Diet
  • Diet, Carbohydrate-Restricted*
  • Disaccharides* / adverse effects
  • Female
  • Fermentation
  • Humans
  • Irritable Bowel Syndrome* / diet therapy
  • Male
  • Middle Aged
  • Monosaccharides* / adverse effects
  • Oligosaccharides* / adverse effects
  • Polymers
  • Prospective Studies
  • Quality of Life
  • Young Adult


  • Disaccharides
  • Monosaccharides
  • Oligosaccharides
  • Polymers
  • polyol