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Is IBS a gut-brain-microbiome axis dysfunction?

22 September, 2022

Is IBS a gut-brain-microbiome axis dysfunction?

Irritable bowel syndrome (IBS) is a common gastrointestinal condition that significantly reduces quality of life. Treatment options, however, have long been limited to just symptom management.

Recently, a new understanding of IBS has emerged.

Research highlights that a dysfunctional interrelationship between gut symptoms, mental health, and the microbiome is responsible for the onset and progression of this disorder.

Read on to learn how a dysregulated gut-brain-microbiome axis can promote IBS and what therapeutic measures can be put in place to reduce IBS symptoms and reverse the course of the disease. 

What is the gut-brain-microbiome axis and how does it influence IBS?

The gut-brain–microbiome axis connects the central nervous system (CNS), which includes the brain and spinal cord, with the enteric nervous system (ENS) of the gut.

This axis facilitates bidirectional communication between the gut and brain (1). The microbiome serves as a key intermediary between the gut and the brain as it produces metabolites that relay messages to both organs (2).

Gut-brain connection looking at gastric organs, brain and skeletal outline
Gut-brain connection

When the gut-brain-microbiome axis is in balance, the digestive system and brain function optimally. Conversely, when the axis is dysregulated, gut-brain symptoms can set in.

Up to 40% of IBS patients will also experience depression, anxiety, and mood disturbances (3), in addition to abdominal pain, bloating, and abnormal bowel movements.

Furthermore, research shows that people with IBS have an altered gut microbiota with reduced diversity of microbial populations and increased prevalence of pathogenic organisms, such as E.coli and Clostridia (45). Factors such as antibiotic use, infection, diet, and stress can all lead to microbiome disruption and contribute to IBS.

Stress is a particularly prevalent contributing factor in the IBS picture.  In a majority of cases, IBS patients exhibit a maladaptive stress response (6).

Interestingly, this enhanced stress response may be influenced by the gut microbes which can send signals from the gut to the brain (7) and incite a pro-inflammatory state leading to intestinal permeability and the leakage of neuroactive metabolites that can harm brain and cognition.

Stress in turn can have harmful effects on the intestinal microbiota (8). For example, adrenaline can increase the virulence of gut pathogens (9) which can further exacerbate IBS symptoms.

The complex relationship between the gut, brain, and microbiome in IBS can create a vicious cycle of gut symptoms, stress, and poor mental health. 

To break this vicious cycle and successfully treat IBS, the gut-brain-microbiome axis must be repaired. 

How to repair the gut-brain-microbiome axis to treat IBS?

A holistic approach that includes modulation of the axis with dietary changes, prebiotics, probiotics, herbal anti-microbials, and stress reduction strategies is necessary to achieve the best outcomes. 

Diet and Prebiotics

Significant positive changes have been associated with the low FODMAP diet.

Gut bacteria metabolise FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols), into short-chain fatty acids (SCFAs). High levels of two SCFAs, acetic acid, and propionic acid, have been associated with gastrointestinal symptoms, anxiety, depression, and reduced quality of life in IBS patients (10).

Reducing dietary intake of FODMAPs can lower levels of these SCFAs and therefore alleviate IBS symptoms (11). 


Probiotics can modulate both the gut and the brain components of the gut-brain–microbiome axis. For example,  Bifidobacterium infantis reduces abdominal pain and bloating and normalises bowel movements, while also inducing antidepressant effects through increasing tryptophan levels in the blood (1213).

Another strain, Lactobacillus acidophilus, decreases intestinal pain in IBS by activating opioid and cannabinoid receptors (14).


Up to 85 percent of IBS patients have small intestinal bacterial overgrowth (SIBO) (15). Herbal anti-microbials such as wormwood, goldenseal, pomegranate, rosemary, and myrrh can be helpful in the eradication of SIBO.

Stress Reduction

The implementation of stress reduction strategies is crucial for breaking the cycle of IBS and restoring health to the gut-brain–microbiome axis.

Yoga, exercise, and mindfulness meditation have demonstrated specific benefits.

A recent study found that yoga practice increases parasympathetic nervous system activity, making it an effective remedial therapy for IBS (16). Exercise decreases inflammation, increases beneficial microbial species in the gut, and improves bowel regularity (1718).

Mindfulness training promotes nonreactive awareness of emotional and sensory experiences and has been found to beneficially alter pain processing (19). 

The IBS diagnosis of IBS does not have to be frustrating. The newfound knowledge of the gut-brain-microbiome axis and the variety of treatments currently available offer the patients the possibility of a full recovery. 

Appointments available in Moonee Ponds or online.

About the Author

Olga Ischenko - Naturopath & Medical Researcher

Olga is dual qualified Clinical Naturopath & Medical Researcher.

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