Ever had “butterflies” in your stomach before a first date or big presentation? That fluttery feeling is your gut-brain axis at work.
For people with irritable bowel syndrome (IBS), the gut-brain axis goes a little haywire, resulting in visceral hypersensitivity and altered gut motility. This turns everyday digestive processes into bloating, pain and urgency.
In this “gut-brain basics” blog, we’ll unpack the gut-brain axis, explore how it shapes IBS symptoms, and examine the role of stress and anxiety.
What Is the Gut-Brain Axis?
The gut-brain axis is the continuous communication loop between the brain and the gut. These two systems stay in constant contact through nerves, hormones, and even the microbes that live in your large intestine. Central to this system is the vagus nerve, which acts like a highway conducting signals back and forth.
More recently, the gut-brain axis has been described as the gut-brain-microbiota axis because the microorganisms in the digestive tract influence communication between the brain and gut as well.
When this communication system stops working properly, it can start to drive persistent symptoms like abdominal pain, bloating and diarrhea.
How the Gut-Brain Axis Shapes Symptoms in IBS
In people with IBS, the gut-brain axis muddles communication between the gut and the brain, causing signals to be amplified or misread.
Two major ways this shows up are though visceral hypersensitivity and altered gut motility, the hallmarks of IBS.
1. Visceral Hypersensitivity in IBS
The gut nerves are extra sensitive in IBS, a phenomenon we called visceral hypersensitivity. In visceral hypersensitivity, normal activity in the gut, such as intestinal stretching to accommodate digested food and contractions to move intestinal contents along, can feel painful.
2. Altered Gut Motility
The gut-brain axis also controls how quickly food moves through your digestive system. The brain may instruct the gut to move its contents along quicker, causing diarrhea, or slower, causing constipation.
A classic example of how faulty communication shapes gut symptoms is the overreactive gastrocolic reflex seen in many people with diarrhea-predominant IBS.
When we eat a meal, the stomach informs the brain that food is arriving in the digestive tract. In response, the brain stimulates the large intestine to contract and move bowel contents along. This is called the gastrocolic reflex.
In IBS, this reflex is exaggerated, leading to urgency and overzealous evacuation of the bowels – aka diarrhea – in those with IBS-D.
Why Stress and Anxiety Affect IBS
Stress and anxiety can directly influence IBS symptoms because they amplify the miscommunication between the gut and the brain.
Many of my IBS-D clients report that instances of acute stress can induce an episode of diarrhea. When the “fight or flight” response is triggered, the stress hormones that the body releases heighten nerve sensitivity, change how gut muscles contarct, and even alter the microbiome.
How to Improve Gut-Brain Communication
The good news? You can improve communication along the gut-brain axis through both lifestyle and therapeutic approaches.
Strategies that may help include:
- Stress-management tools such as mindfulness meditation, deep breathing, or yoga
- Gut-directed hypnotherapy
- Cognitive behavioural therapy for IBS
- Regular meals and gentle movement
- A balanced diet with adequate fibre to nourish a diverse, robust microbiome
The Bottom Line
The gut-brain axis plays a major role in IBS — affecting both pain and bowel motility. Stress and anxiety exacerbate miscommunication between the brain and the gut, thereby worsening IBS symptoms.
Understanding this relationship helps explain why strategies that target both brain and gut can be so effective. By calming the mind, it’s possible to dial down the intensity of IBS symptoms and ultimately feel a lot better.
Thanks for reading!
xoAndrea, RD
