You might not have made a connection between the vagus nerve and constipation, but this post explains what you need to know. 

The vagus nerve is a super highway of information between your brain and your gut. What goes on in vagus does NOT stay in vagus! In this blog post I’ll explain what the vagus nerve does, how it affects your digestion and crucially what you can do to support it. 

Let’s start with the basics..

What is the vagus nerve? 

The vagus nerve is a key communication channel that helps your digestive tract receive messages from your brain. Additionally, it helps your brain understand what’s going on with nutrient absorption, bacteria, energy balance (including our hunger and fullness signals), and immune reactions in the gut.

And you might think your brain is in control, but it’s thought around 90% of the traffic in the vagus nerve is upwards to the brain from the stomach, liver, and intestines.

So actually only around 10% of traffic is coming from the top down this nerve pathway.

Your nervous system recap

Let me just quickly explain a bit about the nervous system to give you some context. There are three nervous systems that are operating all day and night without your conscious control. These are the:

• Sympathetic nervous system – the fight or flight response
• Parasympathetic nervous system – controlling our rest and digest state
• Enteric nervous system – This is stimulated by the vagus nerve, but our digestion has its own nervous system. It  controls your digestive blood flow, mucus secretions and local hormones. It’s capable of operating even without the brain! 

All these systems are connected, and have a different role.

Parasympathetic nervous system – your rest and digest mode

The vagus nerve is part of your parasympathetic nervous system which is our calming ‘Rest or Digest’ state. This helps to relax blood vessels, allows blood to flow to the digestive tract. It also helps us produce saliva and stomach acid.

We can’t control this unfortunately, we can’t choose to turn our stomach acid on or off! Other similar functions we can’t control include our blood pressure, dilation of blood vessels and digestive motility. 

If you are always rushing around, and feeling chronically stressed it could affect your constipation.

Triggering your ‘fight or flight’ mode all the time means you won’t have full functioning of this parasympathetic state, which includes digestive motility.

This makes sense, your body will not prioritise digestion when faced with a mortal threat! However, it also means your production of stomach acid, gut motility and general digestive health will be reduced.

In a fight or flight state the gut hears the message – ‘Stop what you’re doing’, which can lead to constipation as your gut motility slows down. Or it might hear the message ‘Do that quicker, we need to get on to something more important!’ which could lead to reduced breakdown of food, triggering bloating and gas. 

What does the vagus nerve actually do?

It’s named after the word vagrant, as in wanderer or vagrant because it stretches out into our torsos (nothing to do with Las Vagas!)

The nerve touches all our digestive organs, as well as heart rate and breathing. It’s involved in controlling many of your digestive functions, which if not functioning well, can affect constipation. For example, your vagus nerve has an effect on:

• downward movement in the gut, including peristalsis (movement of the food through the gut) which can lead to slow motility. If you have a slow gut transit time you may end up with constipation as the stool dries out the longer it’s been in your large intestine.
• release of bile from the gallbladder to help digest fats. Bile is antimicrobial, but also can stimulate gut motility so if you’re not releasing bile effectively it could be reducing the speed of gut transit. 
• production of digestive juices from saliva to stomach acid which helps breakdown our food.

Does your vagus nerve slow down gut motility? 

Studies in animals seem to show that triggering the vagus nerve can improve constipation. There was a study on rats who were treated with anti-diarrhoea medication to mimic opioid induced constipation.

Researchers found the rats had more bowel movements when their vagus nerve was stimulated. Rats who didn’t have their vagus nerve stimulated remained constipated.

The rodents were fitted with a contraption to stimulate the vagus nerve through their ear. To provide a control group there was another group of rats who had the stimulation machine on, but the vagus nerve was severed. Rats which had their vagus nerve cut didn’t see any benefit to the stimulation. 

So, whilst this is just a rodent study, it shows that stimulating the nerve could help with sluggish bowel.

Exercises for the vagus nerve and constipation

You can support your vagus nerve with simple activities that are mostly all easy to try. 

These need to be done regularly to stimulate the muscles around the throat and the vagus nerve. You won’t just be better after doing this once, it’s a long term goal.

I think it’s worth adding these kinds of things into your daily routines because these are free, risk free and can support better nervous system health. 

1. COLD WATER EXPOSURE – 

Exposure to acute cold can help to stimulate the vagus nerve. Build up your tolerance slowly. You could try cold water swimming if you want to really go for it, or even just a 30 second cold shower after washing. 

2. SLOW DEEP BREATHS

Long exhalations can activate the parasympathetic nervous system, helping us feel calm. Take 5+ slow long exhalations, especially before eating anything. This helps the vagus nerve and constipation by massaging the gut internally, and also reducing stress. 

3. MEDITATION

Practice slowing down your busy brain with regular meditation. It’s not about clearing your mind, it’s about being present in the moment. This is an ongoing practice for most people and if it doesn’t come easy at first stick with it. 

4. GARGLING

Try for around 2-3x a day everyday for at least 4 weeks. You want to do this with enough force that you make a loud noise, and even start to feel yourself gagging. This will stimulate the muscles at the back of the throat. 

5. HUMMING

really loud and strong humming, try this in the car or the shower if you feel embarrassed of making such a loud noise! 

6 LAUGHTER

As well as dispelling some of the stress hormones, laughing helps ‘reset’ your breathing, and encourages deep breaths. 

7 EXERCISE

Movement can lower fight or flight response and help encourage deep breathing. Exercise also helps to urn off high stress hormones, leaving us more relaxed. Exercise could also help stimulate a bowel movement through muscle stimulation.

Let me know if you’ve had any success with any of these practices for the vagus nerve and constipation, I’d love to hear how you get on with them.