Enhancing digestion through the vagus nerve

Do you ever suffer from bloating, gas, indigestion, or reflux that seems to stick around no matter what you do?

When we think of digestion, we automatically link it to our stomach, liver, intestines, and colon, but did you know that most of our digestive function is controlled by a nerve? The vagus nerve is the longest nerve in our body, running from the brain stem all the way down to the abdomen.

It is responsible for controlling many different functions in the body, including heart rate, digestion, and immune function as a part of our parasympathetic nervous system, otherwise known as ‘rest and digest’ part of the nervous system.

The digestive system is a complex network of organs that work together to break down food and absorb nutrients. The vagus nerve is intimately involved in this process, helping to regulate many aspects of digestion, from the release of stomach acid to the movement of food through the intestines.

Its work begins as soon as we start to chew: sensing that we are about to be digesting, the vagus nerve sends a signal to the stomach, so that it starts producing acid. This acid is essential for breaking down food and killing harmful bacteria that may be present and when it is too low can cause symptoms like indigestion and reflux.

But it doesn’t stop there! Simultaneously the vagus nerve begins to facilitate the movement of food through the intestines as our food enters the stomach. This causes the muscles of the stomach to contract, mixing the food with the digestive acids and enzymes that have been produced!

As the food is broken down, it is gradually pushed through the intestines by a series of rhythmic contractions, known as peristalsis. The vagus nerve helps to coordinate this process, ensuring that food is moved through the digestive system at the right pace.

The Gut-brain axis

The gut-brain axis refers to the complex communication system that exists between the gut and the brain. This includes the neural, hormonal, and immune pathways that connect the gut and the brain, allowing them to communicate and influence each other.

Research has shown that the vagus nerve plays a crucial role in the gut-brain axis, helping to regulate digestion, inflammation, and mood. For example, studies have found that stimulation of the vagus nerve can help to reduce symptoms of depression and anxiety, improve gut motility, and decrease inflammation in the body (1).

Conversely, disruptions to the gut-brain axis, such as through poor diet, stress, or inflammation, can have negative effects on the vagus nerve and overall health. For example, chronic stress has been shown to impair vagus nerve function, leading to decreased digestive function and increased inflammation (2)

The Vagus nerve’s role in appetite and digestion

In addition to regulating the physical aspects of digestion, the vagus nerve also plays a role in regulating the release of hormones that control appetite and digestion. For example, the hormone ghrelin, which stimulates hunger, is released when the stomach is empty. The vagus nerve helps to stimulate the production of ghrelin, helping to ensure that you feel hungry when you need to eat (3)

The vagus nerve and inflammation

Finally, the vagus nerve also plays a role in regulating inflammation in the digestive system. Inflammatory bowel disease (IBD), which includes conditions such as Crohn’s disease and ulcerative colitis, is characterized by chronic inflammation in the digestive tract. Research has shown that the vagus nerve plays a role in regulating this inflammation, and that stimulating the nerve may help to reduce symptoms in people with IBD (4)

Symptoms that may be caused by low vagus nerve function:

• Small intestinal bacteria overgrowth (SIBO)- A condition whereby certain bacteria that should normally only be present in the colon is located in the small intestine and causes severe bloating, gas, indigestion, constipation and/or diarrhea, stomach cramping and notable an intolerance to garlic, onion, legumes and other fermentable carbohydrates.
• Bloating and indigestion
• Constipation
• Acid reflux
• Fainting – otherwise known as vasovagal syncope
• Feeling full to quickly or loss of appetite
• Mood disorders such as depression or anxiety that don’t respond to conventional treatment methods

What can cause low vagus nerve function?

• Infection
• Inflammation
• Traumatic brain injury
• Stroke
• Gut dysbiosis
• Vagus nerve stimulation

If you’re experiencing irregular bowel motions, bloating, constipation, low appetite or indigestion the there are a few ways to stimulate your vagus nerve, and they can be done anywhere and (almost) anytime!

• Gagging
• Singing – specifically high register to low (pop on a Mariah Carey tune)
• Coughing
• Shouting
• Exercise
• Sitting in a relaxed space before eating and meals and taking some deep belly breaths

There could be many contributing factors as to why you are having digestive symptoms and its important to understand what the underlying drivers could be. If you would like some help investigating all the many and varied things that could be impacting your digestion, I would love to support you.

Author Margaret Scott Naturopath BhSc

Margaret is a degree qualified naturopath with a focus on women’s hormonal and digestive health throughout the lifespan. Learn more about Margaret here Book a session with Margaret here

References

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5859128/

2. https://pubmed.ncbi.nlm.nih.gov/29593576/

3. https://pubmed.ncbi.nlm.nih.gov/22975058/

4. https://pubmed.ncbi.nlm.nih.gov/36233558