Can We Predict Which Patients With Irritable Bowel Will Respond to Dietary Manipulation Based on Their Microbiome?

Quote From Martin Short

In a recent post regarding Next-Generation Treatment for H pylori, the authors denigrated the term “empiric” treatment and said a more accurate term would be “hopeful” therapy. There are a lot of areas in our field in which hopeful therapy is a mainstay, especially in those with non-organic abdominal pain (eg. irritable bowel syndrome). Even with the benefit of a therapeutic ‘regression to the mean,’ treatment is often unsatisfactory.

Thus, it is a very positive sign that a recent article provides an indication of which patients are most likely to benefit from dietary manipulation:

K Vervier et al. Gut 2021;gutjnl-2021-325177. doi: 10.1136/gutjnl-2021-325177. Online ahead of print: Open Access: Two microbiota subtypes identified in irritable bowel syndrome with distinct responses to the low FODMAP diet

Methods: A prospective single centre case–control study recruited participants (n=56 pairs) from 2016 to 2019. The authors included adults (18–68 years of age) meeting the Rome IV criteria for diarrhoea-predominant or mixed type IBS (IBS-D and IBS-M, respectively) with respective household controls. 

Key findings:

  • Baseline IBS cases pre-diet identified two distinct microbiota profiles, which we refer to as IBSP (pathogenic-like) and IBSH (health-like) subtypes.
  • IBSP microbiomes were enriched in Firmicutes and genes for amino acid and carbohydrate metabolism, but depleted in Bacteroidetes species.
  • IBSH microbiomes were similar to controls.
  • On the low FODMAP diet, IBSH and control microbiota were unaffected, but the IBSP signature shifted towards a health-associated microbiome with an increase in Bacteroidetes (p=0.009), a decrease in Firmicutes species (p=0.004) and normalization of primary metabolic genes. The clinical response to the low FODMAP diet was greater in IBSP subjects compared with IBSH (p=0.02).
  • 50% of IBS cases manifested a ‘pathogenic’ gut microbial signature. This shifted towards the healthy profile on the low FODMAP diet; and IBSP cases showed an enhanced clinical responsiveness to the dietary therapy
A) Beta diversity analysis of IBS cases and healthy controls: principal coordinate analysis for the two first components identifies two distinct clusters among cases, described as cluster 1 (cl1, red) and cluster 2 (cl2, blue). Overall dispersion of household controls is represented in grey.

My take: Currently, what is a “pathogenic” microbiome is unclear at least to me. However, changes in the microbiome do occur with dietary manipulation and are likely involved in response to treatment for IBS and other disorders.

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2 thoughts on “Can We Predict Which Patients With Irritable Bowel Will Respond to Dietary Manipulation Based on Their Microbiome?

  1. Pingback: Gluten-Free Diet –Role in IBS? | gutsandgrowth

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