Low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols diet compared with traditional dietary advice for diarrhea-predominant irritable bowel syndrome: a parallel-group, randomized controlled trial with analysis of clinical and microbiological factors associated with patient outcomes

Abstract

Background The efficacy and factors associated with patient outcomes for a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (LFD) compared with traditional dietary advice (TDA) based on modified National Institute for Clinical Excellence guidelines for irritable bowel syndrome with diarrhea (IBS-D) in regions consuming a non-Western diet are unclear. Objectives We aimed to determine the efficacy of an LFD compared with TDA for the treatment of IBS-D in Chinese patients and to investigate the factors associated with favorable outcomes. Methods One hundred and eight Chinese IBS-D patients (Rome III criteria) were randomly assigned to an LFD or TDA. The primary endpoint was a ≥50-point reduction in the IBS Severity Scoring System at 3 wk. Fecal samples collected before and after the dietary intervention were assessed for changes in SCFAs and microbiota profiles. A logistic regression model was used to identify predictors of outcomes. Results Among the 100 patients who completed the study, the primary endpoint was met in a similar number of LFD (30 of 51, 59%) and TDA (26 of 49, 53%) patients (∆6%; 95% CI: −13%, 24%). Patients in the LFD group achieved earlier symptomatic improvement in stool frequency and excessive wind than those following TDA. LFD reduced carbohydrate-fermenting bacteria such as Bifidobacterium and Bacteroides, and decreased saccharolytic fermentation activity. This was associated with symptomatic improvement in the responders. High saccharolytic fermentation activity at baseline was associated with a higher symptom burden (P = 0.01) and a favorable therapeutic response to the LFD (log OR: 4.9; 95% CI: −0.1, 9.9; P = 0.05). Conclusions An LFD and TDA each reduced symptoms in Chinese IBS-D patients; however, the LFD achieved earlier symptomatic improvements in stool frequency and excessive wind. The therapeutic effect of the LFD was associated with changes in the fecal microbiota and the fecal fermentation index. At baseline, the presence of severe symptoms and microbial metabolic dysbiosis characterized by high saccharolytic capability predicted favorable outcomes to LFD intervention. This trial was registered at clinicaltrials.gov as NCT03304041.

Efficacy of a low FODMAP diet in irritable bowel syndrome: systematic review and network meta-analysis

“…The search strategy generated 1231 citations, 79 of which appeared relevant and were retrieved for further assessment (Supplementary Figure 1). Of these, we excluded 66 that did not fulfil eligibility criteria, leaving 13 eligible articles, [28,29,33,[52][53][54][55][56][57][58][59][60][61] which included 944 patients, 472 of whom were allocated to a low FODMAP diet. Twelve RCTs evaluated low FODMAP dietary advice, [28,33,[52][53][54][55][56][57][58][59][60][61] and one RCT evaluated a low FODMAP diet in which participants were provided with the majority of food to be consumed and advised about fluid choices throughout the duration of the intervention.…”

“…Of these, we excluded 66 that did not fulfil eligibility criteria, leaving 13 eligible articles, [28,29,33,[52][53][54][55][56][57][58][59][60][61] which included 944 patients, 472 of whom were allocated to a low FODMAP diet. Twelve RCTs evaluated low FODMAP dietary advice, [28,33,[52][53][54][55][56][57][58][59][60][61] and one RCT evaluated a low FODMAP diet in which participants were provided with the majority of food to be consumed and advised about fluid choices throughout the duration of the intervention. [29] In terms of the alternative intervention, 237 patients received BDA/NICE dietary advice for IBS in five RCTs, [33,[52][53][54][55] 106 were allocated to habitual diet in four RCTs, [28,29,56,57] 76 were randomised to sham dietary advice in two trials, [58,59] 33 were allocated to alternative brief dietary advice in one RCT, [60] and 20 received a high FODMAP diet in one trial (Supplementary Table 2).…”

“…We obtained extra data from the investigators of seven RCTs. [53, [55][56][57][58][59][60] Risk of bias for all included trials is reported in Supplementary Table 3. No RCT was at low risk of bias across all domains, although nine trials were low risk of bias across all domains other than double blinding.…”

“…No RCT was at low risk of bias across all domains, although nine trials were low risk of bias across all domains other than double blinding. [28,52,[54][55][56][57][58][59]61] Dietary trials are inherently difficult to blind, but two trials stated that investigators were blinded to treatment allocation, [33,55] and eight that patients were blinded. [29, [52][53][54][58][59][60][61] Endpoints used, or imputed, in each trial are provided in Supplementary Table 4.…”

Review Article: Current and future treatment approaches for IBS with diarrhoea (IBS‐D) and IBS mixed pattern (IBS‐M)

“…One study of IBS-D patients randomised to the low FODMAP diet or traditional dietary advice found that responders of the low FODMAP diet were those with baseline higher dysbiosis characterised by higher saccharolytic fermentation (ie the capability of the colonic microbiota to digest carbohydrates usually due to increased amount of Bacteroides species and some strains of Prevotella) and could predict the response to low FODMAP diet. 29,30 Despite these limitations, a short trial with the low FODMAP diet is generally recommended as a dietary treatment for IBS.…”