Irritable Bowel Syndrome and the Vagus Nerve

Irritable bowel syndrome (IBS) causes uncomfortable digestive symptoms. But IBS is not just about your gut. It also involves the brain and nervous system. There is a complex connection between the digestive tract (stomach and intestines) and the brain. Researchers are working to better understand how this connection impacts people with IBS.^1-3

What is IBS?

IBS is a functional gastrointestinal (GI) disorder. This means that while the symptoms are very real, the stomach and intestines appear normal on routine tests.¹

IBS causes uncomfortable GI symptoms, including:⁴

• Abdominal discomfort or pain
• Stomach cramping
• Gas and bloating
• Hard and infrequent bowel movements (constipation)
• Frequent and loose, watery bowel movements (diarrhea)
• Suddenly needing to use the restroom

Gut-brain axis and IBS

IBS symptoms are influenced by a complex network in the body called the gut-brain axis (GBA). The GBA is like a superhighway that sends messages between the digestive tract (gut) and the brain.^1-3

An imbalance in the GBA interferes with normal signals between the gut and the brain. For people with IBS, normal sensations, like food moving through the intestines, are sensed as painful.¹

What is the vagus nerve?

The nervous system is a major part of the GBA. The vagus nerve is part of your body’s autonomic nervous system. The autonomic nervous system controls body functions that happen without you thinking about them.^1,5-7

The autonomic nervous system is divided into 2 parts:^1,5-7

• Sympathetic nervous system “fight or flight” – This system helps your body respond to stress or danger.
• Parasympathetic nervous system “rest and digest” – This system helps your body relax after times of stress and balances the “fight or flight” response.

The vagus nerve is the major nerve of the parasympathetic nervous system. The vagus nerve is also called the tenth cranial nerve, or cranial nerve X. It is the longest cranial nerve, traveling from the brain, through both sides of the neck, and to the heart and intestines.⁵

The vagus nerve carries signals that promote relaxation and digestion. Some of the other functions controlled by the vagus nerve include:⁵

• Breathing
• Heart rate
• Blood pressure
• Immune system
• Sexual arousal

Vagus nerve and IBS

Along with many other functions, the vagus nerve plays a major role in IBS. The vagus nerve carries messages back and forth between the gut and brain. These messages are affected by stress, thoughts, sensations, and gut function. When the vagus nerve is not working well, it can lead to GI sensitivity and disrupt normal digestion.^1-3

Vagus nerve and neck pain

Since the vagus nerve travels through the neck, you may wonder if neck pain could affect vagal function and lead to IBS symptoms. However, research has not shown a clear link between neck pain and IBS.⁸

Vagus nerve stimulation

A branch of the vagus nerve near the ear can be stimulated with electrical signals applied through the skin. Stimulating the vagus nerve with electrical signals is used to treat depression and seizures.^2,9,10

Vagus nerve stimulation has also been shown to affect pain perception and how food moves through the intestines. While more research is needed, scientists are exploring if nerve stimulation can help people with IBS.^2,9,10

Natural ways to stimulate the vagus nerve

Balanced vagus nerve function is crucial for your overall health. Factors like stress and age can impact how well the vagus nerve works.¹¹

Along with electrical stimulation, there are natural ways to support vagal function. Ways to naturally stimulate the vagus nerve and reduce stress include:¹¹

• Practicing meditation and yoga
• Taking slow, deep breaths
• Exercising
• Getting a massage, especially a type of foot massage called reflexology
• Taking a cold shower or bath
• Singing or listening to soothing music

Many factors play a role in IBS. The vagus nerve is one part of this complex disorder. Understanding the connection between the nervous system and IBS will help doctors develop better ways to treat and prevent IBS.