Exploring the Role of the Gut-Brain Axis in Irritable Bowel Syndrome

In this lesson we’ll explore the connection between your gut and brain, and how this relationship has changed how experts think about IBS.

By Laura Tilt

Ever had butterflies in your tummy before a big event? Or have to rush to bathroom when feeling nervous before a date or exam? This is your gut-brain axis at work. 

What's the Gut-Brain Axis?

Scientists use the phrase 'gut-brain axis’ to describe the communication channels that exist between your brain and gut.

The gut brain axis has both physical and chemical communication channels which include:

1 - The Vagus Nerve

The Vagus Nerve is the longest nerve in your body. It runs from your brain all the way into your large intestine. Think of it like a long telephone wire connecting your brain and gut. The Vagus nerve sends signals from the gut to the brain and vice-versa. It monitors what’s going on in the gut, it regulates digestion and connects the emotional and thinking areas of your brain with gut function.

2 – Gut microbes

Compounds produced by the microbes in your gut travel via the Vagus nerve. They affect brain function by regulating the production of neurotransmitters (chemical messengers). Your gut microbes also produce and respond to the same neurotransmitters that your brain makes. For example, the neurotransmitter serotonin promotes feelings of happiness but also controls gut motility (movement).

What’s the gut brain axis got to do with IBS?

For decades, IBS has been called a ‘functional gut disorder’. A functional disorder is where the normal functioning of a body system is disrupted, without any explanation.

In the case of IBS, the gut looks normal but isn’t functioning normally, leading to symptoms like tummy pain and a change in your poo.

More recently, research has shown that the communication signals between the gut and brain become dysregulated in IBS. This leads to changes in how the gut functions and increases the sensitivity of the gut wall, resulting in a wide range of symptoms.

As a result of this research, experts re-classified IBS as a disorder of gut–brain interaction. This re-naming hasn’t changed how we treat IBS – but it does give us more clues about how the condition develops.

Join us in the next lesson to learn about the relationship between stress and IBS symptoms.