Supplementing Dietary Fibers With a Low FODMAP Diet in Irritable Bowel Syndrome: A Randomized Controlled Crossover Trial

doi:10.1016/j.cgh.2021.12.016

Clinical Gastroenterology and Hepatology

Volume 20, Issue 9, September 2022, Pages 2112-2120.e7

https://doi.org/10.1016/j.cgh.2021.12.016 Get rights and content

Background & Aims

Institution of a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) in patients with irritable bowel syndrome (IBS) may lead to inadequate fiber intake. This trial aimed to investigate the effects of supplementing specific fibers concomitantly with a low FODMAP diet on relevant clinical and physiological indices in symptomatic patients with IBS.

Methods

A double-blind crossover trial was conducted in which 26 patients with IBS were randomly assigned to 1 of 3 low FODMAP diets differing only in total fiber content: control, 23 g/d; sugarcane bagasse, 33 g/d; or fiber combination (sugarcane bagasse with resistant starch), 45 g/d. Each diet lasted 14 days with most food provided and ≥21 days’ washout between. Endpoints were assessed during baseline and dietary interventions.

Results

From a median IBS Severity Scoring System total score at baseline of 305, all diets reduced median scores by >50 with no differences in rates of symptom response between the diets: control (57%), sugarcane bagasse (67%), fiber combination (48%) (P = .459). Stool output was ∼50% higher during the fiber-supplemented vs control diets (P < .001 for both). While there were no overall differences overall in stool characteristics, descriptors, and water content, or in gastrointestinal transit times, supplementation with sugarcane bagasse normalized both low stool water content and slow colonic transit from during the control diet.

Conclusions

Concomitant supplementation of fibers during initiation of a low FODMAP diet did not alter symptomatic response in patients with IBS but augmented stool bulk and normalized low stool water content and slow transit. Resistant starch did not exert additional symptomatic benefits over sugarcane bagasse alone. (Australia and New Zealand Clinical Trial Registry; Number, ACTRN12619000691145).

Graphical abstract

Section snippets

Participants

Participants 18–65 years of age with IBS according to Rome IV criteria⁸ were recruited via social media and word of mouth between June 2019 and September 2020. They were required to have overall gastrointestinal symptoms that averaged >30 mm over a 5-day prescreening via a 100-mm visual analog scale (VAS) as previously applied,⁹ in which 0 mm indicated no symptoms and 100 mm represented the worst symptoms experienced. Additional exclusion criteria are outlined in the Supplementary Material.

Trial Protocol

In a

Participants

Twenty-six participants were recruited. The median age was 34 (range, 18–61) years, 25 were female, and median body mass index was 22.8 (range, 16.2–30.7) kg/m². Seven participants were self-classified as constipation-predominant, 8 were diarrhea-predominant, 8 were mixed, and 3 were unknown as per Rome IV criteria. An a priori interim analysis of the primary endpoint was performed by an independent statistician using the data available at that time (n = 16 completed) without unblinding;

Discussion

This trial is the first to evaluate the effects of concomitant fiber supplementation with initiation of a low FODMAP diet in patients with IBS. The primary findings were that a minimally fermented fiber, sugarcane bagasse, alone and in combination with fermentable RS, augmented stool output compared with low FODMAP diet alone and did not diminish the clinical efficacy of reducing FODMAP intake. Additionally, post hoc analyses showed that the fibers were associated with normalizing stool water

Acknowledgements

The authors thank the volunteers who participated in this trial. Many thanks to Lyndal Collins, Dr Paul Gill, and Trish Veitch for their assistance with designing the low FODMAP background diet, as well as to the many Nutrition and Dietetic Students and Workplace Integrated Learning interns from Monash University, for cooking the meals for the background diet meals and producing the cereals, respectively. Special thanks to Luke Farrell of Baker’s Delight for developing and producing the bread

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Screening dietary fibres for fermentation characteristics and metabolic profiles using a rapid in vitro approach: implications for irritable bowel syndrome
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Cited by (14)

Assessing ‘response’ to the low-FODMAP diet in irritable bowel syndrome: Should we be reporting harder primary endpoints?
2024, Clinical Nutrition
The low-FODMAP diet (LFD) has become almost synonymous with IBS care, yet the challenges associated with this rigorous therapeutic approach are often underacknowledged. Despite positive outcomes in RCTs, comparator groups frequently exhibit substantial response rates, raising questions about the definition of ‘response’. Whilst the assessment of response in drug trials has evolved to utilize the more stringent FDA/EMA primary clinical endpoints, trials of the LFD have not yet followed. The aim of this article is to opine whether the current approach to the measurement of clinical response to the LFD in clinical trials should be reconsidered.
A comprehensive literature review of LFD clinical trials from the past decade was conducted, focusing on recorded response metrics for primary clinical endpoints.
While response definitions vary, the 50-point IBS-SSS delta emerged as the predominant metric. Notably, no trials to date have adopted the more stringent primary clinical endpoints used in drug trials. Other response measures included binary response metrics (such as ‘adequate clinical response’), changes in visual analogue scales or stool form/output, reductions in abdominal pain, as well as changes the magnitude of the IBS-SSS delta. Whether these metrics correspond to a clinically meaningful improvement for the patient is less clear, and as such aligning patient-clinician expectations can be challenging.
A paradigm shift in the conceptualization of ‘response’ coupled with an emphasis on harder clinical endpoints in the context of clinical trials may serve to better justify the trade-off between symptom-improvement and the inherent challenges associated with this burdensome therapeutic approach.
Sex-Dependent Efficacy of Dietary Fiber in Pediatric Functional Abdominal Pain
2024, Gastroenterology
Functional abdominal pain disorders (FAPDs) are more prevalent in female patients. Dietary fiber may alleviate FAPD symptoms; however, whether this effect is sex dependent remains unclear. We investigated the sex dependency of dietary fiber benefit on abdominal pain in children with FAPDs and explored the potential involvement of the gut microbiome.
In 2 cross-sectional cohorts of children with FAPDs (n = 209) and healthy control individuals (n = 105), we correlated dietary fiber intake with abdominal pain symptoms after stratifying by sex. We also performed sex-stratified and sex-interaction analyses on data from a double-blind trial in children with irritable bowel syndrome randomized to psyllium fiber (n = 39) or placebo (n = 49) for 6 weeks. Shotgun metagenomics was used to investigate gut microbiome community changes potentially linking dietary fiber intake with abdominal pain.
In the cross-sectional cohorts, fiber intake inversely correlated with pain symptoms in boys (pain episodes: r = –0.24, P = .005; pain days: r = –0.24, P = 0.004) but not in girls. Similarly, in the randomized trial, psyllium fiber reduced the number of pain episodes in boys (P = .012) but not in girls. Generalized linear regression models confirmed that boys treated with psyllium fiber had greater reduction in pain episodes than girls (P = .007 for fiber × sex × time interaction). Age, sexual development, irritable bowel syndrome subtype, stool form, and microbiome composition were not significant determinants in the dietary fiber effects on pain reduction.
Dietary fiber preferentially reduces abdominal pain frequency in boys, highlighting the importance of considering sex in future dietary intervention studies for FAPDs. (ClincialTrials.gov, Number NCT00526903)
Systematic review and meta-analysis of habitual intake of fermentable oligo-, di-, mono- saccharides and polyols in the general population and revisiting the low FODMAP diet concept
2024, Journal of Functional Foods
The present systematic review and meta-analysis summarized data on habitual intake of oligo-, di-, mono-saccharides and polyols from 71 studies (n = 138,653 subjects) using random-effects model. In the general population, overall habitual intake of total FODMAPs is 19.86 (95 % CI: 18.12, 21.6) g/d. No differences were observed on habitual intake of individual constituents of designated FODMAPs between healthy and those who are suffering with functional gastrointestinal disease and other GI disorders. Multiple meta-regression adjusted with macronutrient components showed that IBS-SSS score is positively correlated with lactose (R² = 77.78 %, P = 0.006) and total FODMAPs (R² = 78.48 %, P = 0.0052), but not other individual constituents of designated FODMAPs e.g. fructans, GOS, and total polyols. Macronutrient components such as fat (in 6 out of 6 models) and carbohydrate (in 5 out of 6 models) were positively associated with IBS-SSS score. Our findings add insight on current knowledge of FODMAPs habitual intake in the general population and showed that individual FODMAPs such as lactose and other macronutrient components (fat and carbohydrate) as a constituent significantly related to symptom severity.
A randomized dietary intervention to increase colonic and peripheral blood SCFAs modulates the blood B- and T-cell compartments in healthy humans
2022, American Journal of Clinical Nutrition
SCFAs have immune-modulating effects in animal models of disease. However, there is limited evidence that this may occur in humans.
This study aimed to determine the effects of increased exposure to SCFAs via dietary manipulation on colonic fermentation and adaptive immune cells.
Twenty healthy young adults (18–45 y of age) underwent a blinded randomized crossover dietary intervention, consuming a high-SCFA diet and a matched low-SCFA diet for 21-d with a 21-d washout in between. SCFAs were provided through resistant starch, inulin, and apple cider vinegar. Blood and 3-d total fecal output were collected at baseline and at the end of each diet. GC was used to measure fecal and plasma SCFA. Flow cytometry was used for peripheral blood immunophenotyping.
According to a paired samples Wilcoxon test, the high-SCFA diet was associated with significantly higher fecal SCFA concentrations [median (IQR); 86.6 (59.0) compared with 75.4 (56.2) µmol/g, P = 0.02] and lower fecal ammonia concentrations [26.2 (14.7) compared with 33.4 (18.5) µmol/g, P = 0.04] than the low-SCFA diet. Plasma propionate [9.87 (12.3) compared with 4.72 (7.6) µmol/L, P = 0.049] and butyrate [2.85 (1.35) compared with 2.02 (1.29) µmol/L, P = 0.03] were significantly higher after the high-SCFA diet than after the low-SCFA diet. Blood total B cells [184 (112) compared with 199 (143) cells/µL, P = 0.04], naive B cells [83 (66) compared with 95 (89) cells/µL, P = 0.02], Th1 cells [22 (19) compared with 29 (16) cells/µL, P = 0.03], and mucosal-associated invariant T cells [62 (83) compared with 69 (114) cells/µL, P = 0.02] were significantly lower after the high-SCFA diet than the low-SCFA diet.
Increasing colonic and peripheral blood SCFA has discrete effects on circulating immune cells in healthy humans following 3-wk intervention. Further studies (e.g., in patients with inflammatory disease) are necessary to determine whether 1) these changes have immunomodulatory effects, 2) they are therapeutically beneficial, and 3) prolonged intake might be required. This trial is registered at the Australian New Zealand Clinical Trials Registry as ACTRN12618001054202.
The Role of the FODMAP Diet in IBS
2024, Nutrients
Myths and Facts about Food Intolerance: A Narrative Review
2023, Nutrients

View all citing articles on Scopus

: Conflicts of interest All authors work in a department that financially benefits from the sales of a digital application and booklets on the low FODMAP diet. Funds raised contribute to research of the Department of Gastroenterology and to the University. No author receives personal remuneration.

: Funding This work was partly funded by the National Health and Medical Research Council of Australia (APP1154969) and partly funded by Tamu Innovations through the Graduate Research Industry Partnership at Monash University. Daniel So was supported by scholarships from Monash University via the Faculty of Medicine, Nursing and Health Science, and the Graduate Research Industry Partnership.

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Original ArticleFunctional DisordersSupplementing Dietary Fibers With a Low FODMAP Diet in Irritable Bowel Syndrome: A Randomized Controlled Crossover Trial

Background & Aims

Methods

Results

Conclusions

Graphical abstract

Section snippets

Participants

Trial Protocol

Participants

Discussion

Acknowledgements

Gastroenterology

Metabolism

Gastroenterology

Am J Clin Nutr

Adv Nutr

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

Gut

Review article: FODMAPS, prebiotics and gut health-the FODMAP hypothesis revisited

Aliment Pharmacol Ther

Dietary fibres and IBS: translating functional characteristics to clinical value in the era of personalised medicine

Gut

Screening dietary fibres for fermentation characteristics and metabolic profiles using a rapid in vitro approach: implications for irritable bowel syndrome

Br J Nutr

Pilot investigation of the tolerability of dietary resistant starch 2 and non-fermentable fiber, alone or in combination, in healthy participants and patients with irritable bowel syndrome

J Gastroenterol Hepatol (Aust)

Functional gastrointestinal disorders: history, pathophysiology, clinical features and Rome IV

Gastroenterology

Validity and reliability of the Bristol Stool Form Scale in healthy adults and patients with diarrhoea-predominant irritable bowel syndrome

Aliment Pharmacol Ther

Original Article
Functional Disorders
Supplementing Dietary Fibers With a Low FODMAP Diet in Irritable Bowel Syndrome: A Randomized Controlled Crossover Trial