The participants responding positively to the partially hydrolysed guar gum (PHGG) fibre intervention were noted to have increased proportions of Oscillospira and Odoribacter, and lower levels of Prevotella and Faecalibacterium.
The ‘Nutrients’ published report concludes: “In summary, our findings suggest that an individual’s baseline microbiome composition exerts a substantial influence on their response to PHGG for IBS intervention.
“Patients with a normal baseline microbiome diversity not only experienced a significant reduction in IBS symptoms and improvements to their quality-of-life but also exhibited better tolerance to PHGG compared to their low diversity counterparts,” the Australian researchers emphasise.
IBS and nutrition
IBS is a functional disorder characterised by chronic abdominal pain paired with urgent diarrhoea, chronic constipation, or an alternating pattern of both, and is estimated to affect around 5-13% of the overall population. The pathogenesis involves a complex interplay of factors, such as hypersensitivity and intestinal, which ultimately result in an impaired gut barrier and a state of constant inflammation.
Recent research has also reported the significance of a reduced microbiome diversity and faecal SCFA levels in those suffering with IBS. Thus, there have been recommendations based on ‘Level 1 evidence’ regarding the consumption of soluble fibre, particularly partially PHGG, and the beneficial effects to constipation, diarrhoea, and IBS.
Further research established the ability of PHGG to create a favourable environment for the growth of beneficial probiotics, including Lactobacillus and Bifidobacterium, and the enhanced production of various SCFAs.
To further investigate the role of microbial diversity in the pathogenesis of IBS, the researchers conducted the present study to determine the role of the initial gut microbiome of IBS patients, and whether this influences their response to PHGG interventions.
Forty patients with IBS were recruited following a screening process and underwent a 90-day intervention involving daily intakes of 10g of PHGG (FiberChoice, Nestle Vevey, Vaud, Switzerland) mixed with 300ml of water.
Patients then completed an IBS Symptom Severity Score (IBS-SSS) survey, measuring severity of abdominal pain, frequency of abdominal pain, severity of abdominal distension, dissatisfaction with bowel habits, and interference with quality-of-life. Stool samples were also collected for DNA analysis and microbiome sequencing.
It was reported that 65% of included IBS sufferers had a low baseline gut diversity, with significantly lower of species of Prevotella and Faecalibacterium. The normal diversity group were observed to have higher proportions of Oscillospira and Odoribacter.
Following the intervention period, patients with a normal microbiota diversity (Shannon index ≥ 3) showed significant improvements to IBS symptom scores and quality-of-life. These patients were also noted to tolerate the intervention better when compared to those with lower microbiome diversities (Shannon index < 3).
The report concludes that an individual’s baseline microbiome composition may exert a substantial influence on their response to fibre interventions.
The researchers explain the effect: “An increase in genera, Oscillospira and Odoribacter, observed in the normal diversity group may play crucial roles in the utilization of PHGG in the gut.
“Metabolic profiling suggests that Oscillospira is likely capable of producing SCFA, which may contribute to its role in reducing inflammation in the gut.
“Odoribacter, on the other hand, has been shown to be crucial for maintaining a healthy gut, and decreased abundance is associated with conditions such as inflammatory bowel disease, non-alcoholic fatty liver disease, and cystic fibrosis,” they assert.
The researchers urge for further research to investigate interventions incorporating a symbiotic approach involving the combination of specific or multiple probiotics with PHGG to observe any further benefits.
“Role of Baseline Gut Microbiota on Response to Fiber Intervention in Individuals with Irritable Bowel Syndrome”
by Jerry Zhou and Vincent Ho