Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder affecting 4–5% of the global population. This disorder is associated with gut microbiota, diet, sleep, and mental health. This scoping review therefore aims to map existing research that has administrated fibre-related dietary intervention to IBS individuals and reported outcomes on at least two of the three following themes: gut microbiota, sleep, and mental health. Five digital databases were searched to identify and select papers as per the inclusion and exclusion criteria. Five articles were included in the assessment, where none reported on all three themes or the combination of gut microbiota and sleep. Two studies identified alterations in gut microbiota and mental health with fibre supplementation. The other three studies reported on mental health and sleep outcomes using subjective questionnaires. IBS-related research lacks system biology-type studies targeting gut microbiota, sleep, and mental health in patients undergoing diet intervention. Further IBS research is required to explore how human gut microbiota functions (such as short-chain fatty acids) in sleep and mental health, following the implementation of dietary pattern alteration or component supplementation. Additionally, the application of objective sleep assessments is required in order to detect sleep change with more accuracy and less bias.

IntroductionA diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) is an effective way to reduce gut symptoms in people with irritable bowel syndrome (IBS). This diet reduces the intake of fermentable fibres, leading to changes of the gut microbiota and insufficient fermentation in the large bowel, resulting in reduced production of short-chain fatty acids (SCFAs), such as butyrate, which has unfavourable implications for gut health, sleep and mental health. This study will examine the effect of Fibre-fix, a supplement containing a mix of dietary fibres, on the human gut microbiome composition, fermentative capacity, sleep, quality of life (QOL) and mental health of people with IBS who consume a low FODMAP diet (LFD).Methods and analysisA randomised, double-blind, placebo-controlled, study design is proposed to examine whether Fibre-fix added to an existing LFD may help modulate gastrointestinal function, improve markers of sleep, mental health and promote QOL in patients with IBS. Participants will provide stool and blood samples, daily bowel symptoms diaries and 3-day diet records. Additionally, they will complete validated questionnaires relating to FODMAP intake, sleep, mental health and QOL before and after a 3-week intervention. Gut health will be assessed via faecal microbiome composition, faecal pH and SCFA levels. Alteration of sleep will be recorded using an actigraphy device worn by all participants over the whole study. Multivariate analysis will be used to examine the gut microbiome and repeated measures Analysis of variance (ANOVA) will be used for dependent variables from questionnaires related to bowel symptoms, stool type, sleep, mental health and QOL to assess the differences between intervention and control groups after adjustment for confounding variables.Ethics and disseminationEthics approval was obtained from the Human Research Ethics Committee of Edith Cowan University (2019-00619-YAN). Results will be disseminated in peer-review journal publications, and conference presentations. Participants will be provided with a summary of findings once the study is completed. If Fibre-fix is shown to result in favourable changes in gut microbial composition, SCFA production, sleep and mental well-being without exacerbating symptoms, this will provide additional dietary management options for those with IBS following an LFD.Trial registration numberACTRN12620000032954.

Objectives This observational study aimed to assess dietary intake, including resistant starch (RS) in adults with Irritable Bowel Syndrome (IBS), who follow a habitual diet low in Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols (FODMAP) (LFD). Methods Twenty-six participants in Perth, Western Australia with IBS (23 females, aged mean ± SD 37 ± 13 years with a Body Mass Index of 23 ± 3 kg/m2) had FODMAP content assessed using the Monash University Comprehensive Nutrition Assessment Questionnaire and dietary RS from 3-d weighed food diary analysed using published RS values for Australian foods incorporated into a dietary database analysed using FoodWorks 10 (Xyris, QLD, Australia). Descriptive statistics and correlation analysis were performed using SPSS v27(IBM, 2017). Results Out of all participants 35% (n = 9) were on a LFD > 1 year, median 12 months (Interquartile range = 21.8 months), and 77% (n = 20) were at the personalized phase. Median FODMAP intake was 9.6 ± 9.4 g/d and positively associated with the length of time on a LFD, partial correlation (adjusted with BMI and age) was 0.541 (P = 0.003). A therapeutic FODMAP intake <12 g/d (unvalidated) was achieved by 73% (n = 19) of participants. Energy from fat mean ± SD 38.1 ± 9.6% and saturated fat 12.4 ± 3.9% were above Australian recommendations at 20–35% and <10%, respectively. Mean energy contributed by carbohydrates, 36 ± 9.2% was below recommendations (45–65%). Despite the avoidance of plant-based foods high in FODMAP, dietary fibre intake was 20.7 ± 7.4 g/d, equivalent to national Australian studies of adults but less than dietary targets (male 38 g, female 28 g). Habitual RS consumption was 2.1 ± 1.2 g/d, lower than estimations of both typical Australian diets (3.7 (1.9–5.6) g/d) and a LFD study providing all meals (6.9 (3.6–10.3 g/d). Consumptions of vegetables and fruit were 3.9 ± 2.9 and 0.3 ± 1.6 serves/d respectively, and less than the Australian recommendations of 5–6 and 2 serves/d respectively. Conclusions This is the first study in IBS patients to measure RS intake in habitual LFD. Australian adults with IBS consuming a LFD should integrate additional RS sources when personalising their LFD. On the premise that food consumed will not exacerbate IBS symptoms, patients on a LFD should increase the intake of vegetables and fruits based on personal tolerance. Funding Sources Edith Cowan University.