Stop complaining!  My gut has a brain too! 

This article originally appeared in the March 2013 issue of Gut Reaction, the journal of the IBS Network.

You’ve heard about gut feelings, gut reactions or just having the guts for something. It’s true, the gut really does have a mind (or at least a brain) of its own. It’s known as the enteric nervous system and is composed of three extensive networks of nerves sandwiched between the layers of gut wall. Even the brain in our head does not contain as many nerve cells. The gut brain is a vast intelligence network to match the teeming populations of bacteria that take possession of the dark passages inside the abdomen.

Just as the brain in your head takes in information about the environment from eyes, ears, nose, mouth and skin, processes it and reacts to changes, so the brain in the gut senses its contents, processes the information and reacts, making adjustments in contractile activity, secretion of digestive juices and absorption as well as blood flow and immune function while at the same time informing the brain what’s going on.

But what is the relationship between brain inside your gut and the brain in your head?
Think of it like the civil service, which can act autonomously to sort out most everyday problems and concerns, but has to respond to government directives when national security is threatened.  Most of the traffic between the brain and the gut goes one way, informing the brain of what is going on in the gut and activating responses in other parts of the body.  For example, a large meal, especially one that is rich in fat will often cause us to feel relaxed and sleepy and want to find a place to rest. But if we eat too much rich food, the signals are too much and we may feel nauseated, a symptom produced by the vomiting centre of the brain. Conversely, when we take a sweet sugary drink, it can make us feel energetic and accelerate the heart. These feelings are coordinated in the head, but triggered by the gut.

The sympathetic and parasympathetic nervous systems
The brain influences the modality of gut brain function via the sympathetic and parasympathetic nervous systems. The sympathetic nervous (fight and flight) system operates to keep us alert and active and responsive to change. The parasympathetic nervous system is much more conservative. It is necessary for sleep, relaxation, digestion and pregnancy. When we digest a meal, the parasympathetic vagus nerve instructs the various components of the gut brain to coordinate a digestive programme, diverting blood flow to the gut, secreting digestive juices and organizing the contractile activity of the stomach and the small intestine to make sure that food is in the right place for the right time to optimize digestion, while at the same time promoting relaxation. If however, danger threatens, the gut is instructed to cease its digestive programme and even to evacuate its contents by means of vomiting and diarrhea, so that the individual is ready to respond by fight or flight. We’ve all noticed how farm animals evacuate their bowel and bladder when we approach too close.    

Our gut reacts to the daily stress of modern living in the same way it responds to danger.  Having a row while we are eating a meal, or eating ‘on the go’ sets up a conflict in the gut as the sympathetic system tries to inhibit digestion. The result is that we lose our appetite, develop nausea, indigestion, spasm, bloating, pain and bowel upset. Attacks of indigestion, abdominal pain, food intolerance and bowel upset are often triggered by stress.

The gut’s nervous system also has a memory
If you experience an emotional upset while you are eating a meal and you develop gut symptoms, a nervous connection is created between the food, the upset and the symptom – so that if in the future, you eat the same food again, or something reminds you of the emotional upset, then you get the same symptoms.  This means that food intolerance may be caused not so much by a chemical or immunological reaction to a certain food, but by an emotional (mind-gut) reaction to the context in which that food was eaten. 

So to look after the brain in our gut, and hence our gut health, you need not only to watch what you eat but also how you eat it and what is going on in your life. We all tend to be far too busy and rushed, responding to  constant demands – from deadlines to phone calls, emails, tweets and texts. We never seem to have time to rest, we’re constantly on the go, and when we eat, we eat far too much rich, fatty food far too quickly. No wonder we get irritable bowel.   

While hypnotherapy, yoga, meditation, therapeutic massage, acupuncture and reflexology can all help us relax and balance our digestion, it is important for all of us to take time out so we are not “on call” all the time. Paradoxically, regular exercise is one of the best ways of doing this. Try to fit some kind of activity into your daily life but not while you’re eating. Go for a walk in the country, have a swim, go for a bike ride, take a break and your gut will feel better too.   

For more on this subject see an article in Psychology Today in November 2011 by Dan Hurley.

First published March 2014; first published in Gut Reaction March 2013

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