How the connection between the gut and brain affect your health and well-being
Everyone knows the terms ‘gut-wrenching’, ‘butterflies in the stomach’, or ‘going with your gut’. Part of the reason these terms exist in language is that humans know instinctively that there is a connection between the gut and the brain. Scientists have proved that a troubled intestine can send signals to the brain, just as a troubled brain can send signals to the gut.
Medical researchers now know beyond doubt that there’s an intimate link between the gastrointestinal (GI) tract and the brain. That’s why many digestive disorders can also be linked to your emotional state, such as when you experience anxiety, stress, or depression. While there are many other factors that cause GI tract problems, stress has definitely been found to cause stomach upset, even when there isn’t another physical cause. How does this work?
How stress affects the functioning of the GI tract
When you consider the close relationship between the brain and the gut, you’ll start to understand how you can feel ‘sick to your stomach’ when you’re experiencing extreme stress. Some people loathe public speaking and become so nervous beforehand that they will feel completely nauseated. Many physicians will disregard these symptoms as psychological, but psychology can combine with physical factors to cause genuine pain, as well as other symptoms.
Many of the processes of the gut rely on peristalsis (which is a system of coordinated muscular contractions, controlled by the brain). The movement and contraction of these muscles can be influenced by stress, or even depression. As a result, the GI tract can be affected, and digestion will suffer. When there are problems with the GI tract, this can lead to inflammation as well as a range of other problems, such as a negative effect on your immune system, making you more susceptible to infection.
Other research has shown that those with GI disorders actually perceive pain more acutely than others, because the pain signals coming from the gut are not properly regulated. When you’re stressed, this can make the pain worse. So, GI problems can create stress and anxiety, and anxiety and stress can make these GI problems worse. Thus, it becomes a vicious circle. There are many physical symptoms that will demonstrate that you’re stressed – if you heal these, you’ll probably have relief from some of your gut-related problems as well.
Here are some stress-related symptoms:
- Stiff or tense muscles, especially in the neck and shoulders
- Problems sleeping
- Shakiness or tremors
- Grinding teeth
- Difficulty completing work assignments
- Changes in the amount of alcohol or food you consume
- Taking up smoking, or smoking more than usual
- Overwhelming sense of tension or pressure
- Trouble relaxing
- Quick temper
- Poor concentration
- Trouble remembering things
- Loss of sense of humor
If stress has a direct impact on GI problems, it would make sense that someone with the type of symptoms listed above would show an improvement in their condition if they underwent psychological therapy. Numerous studies have taken place to monitor this and the results were very positive. People who tried psychology to relax showed greater improvement in their digestive symptoms than those who underwent conventional medical treatment.
Why the GI tract is referred to as ‘the second brain’
When you think about the nervous system, you most likely think of the brain, the spinal cord, and the network of nerves that travel through the body. Your nerve cells (neurons) contain neurotransmitters, which are chemicals that pass along nerve signals. This network extends from the brain to all parts of the body.
One of the largest parts of your nervous system is located in the gut. This is known as the enteric nervous system (ENS). This system extends along the entire digestive tract from the esophagus all the way down to the rectum, which is a length of over 29 feet. The ENS consists of sheaths of neurons and neurotransmitters embedded in the walls of the gut and alimentary canal, which is why some refer to it as ‘the second brain’. It contains about 100 million neurons, which is more than in the spinal cord or the peripheral nervous system.
This complex neural system is revolutionizing an understanding of the links between digestion, mood, and health. It is now understood that this ENS does much more than just digest food. It communicates with your ‘big’ brain to help balance and maintain your overall health.
How the enteric nervous system in our gut goes way beyond processing food
The ENS and the brain are, of course, in control of food digestion. When you eat and then digest food, the brain is directing much of the process. For example, the moment you look at food, start to feel hungry, and prepare to eat, the brain starts to release the stomach’s juices, so that they’re ready when the food arrives. As a John Hopkins expert explains, “from swallowing, to the release of enzymes that break down food, to the control of blood flow that helps with nutrient absorption, to elimination’ the brain directs the process. There is a constant communication back and forth between the ENS and the brain which allows for the mechanical mixing and rhythmic muscle contractions that move everything down the digestive tract.
What is also believed is that the ENS may cause emotional shifts in people who have digestive disorders such as irritable bowel syndrome (IBS) or bloating, pain, constipation, or diarrhea. The medical world always believed that anxiety and depression were the cause of GI tract disorders such as IBS, but are now starting to think that it might be the other way round. The GI system may actually send signals to the central nervous system that trigger mood changes. This could explain why so many people with digestive disorders are also anxious and depressed.
It goes much further than this. How do we experience happiness and joy? A large part of it comes through producing enough substances such as serotonin, dopamine, endorphins and other neurotransmitters. In order to produce sufficient neurotransmitters, the brain needs proper nutrition (amino acids contain the precursors to neurotransmitter production). If our GI tract isn’t in balance, the brain can become starved, which means that it can’t produce these neurotransmitters or the ‘feel-good’ chemicals that affect our moods. Also, if we have high toxicity in our bodies, the biochemical chains needed to produce the neurotransmitters are blocked. This is a direct link between the gut, your brain, and your moods. It’s another example of how vital it is that your gut is functioning well – it not only affects your health but your entire outlook on life.
Scientists such as Emeran Mayer at UCLA, also feel that “the [digestive] system is way too complicated to have evolved only to make sure things move out of your colon.” He concurs that a large part of our emotions are probably influenced by the nerves in our gut. This is why studies that followed people who were treated for depression found that this had a positive impact on their gut. Of course, this is just a first step – it’s also necessary to heal the gut in order for health and happiness to be restored.
Something most people are aware of is the ‘fight or flight’ response of the nervous system. These responses have protected humans over the ages, and still kick in today. While this response comes from the brain and the central nervous system, the ENS also reacts. It does this by immediately slowing down digestion so that the body’s energy can be diverted to cope with the threat. This would explain why people who live in a state of heightened anxiety could also experience digestive problems.
How does this knowledge help with diagnosing disease?
This field of scientific research is still in its early stage and it will doubtless offer increasing insight into the workings of this ‘second brain’ in the future. The central nervous system has been studied for its connection with disease, but the connection between disease and the gut’s nervous system needs further study. It’s known that at least 70% of your immune system is located in the gut (some say 85%), and the more that’s known about the ‘second brain’ and how its trillion bacteria communicate with the ENS the better.
John Hopkins research indicates that activity in the digestive system may even affect thinking skills and memory. In addition, their research points to how signals from the digestive system affect metabolism and can raise or reduce the risk for certain health conditions like type 2 diabetes. All of these new findings require extensive further research but show the powerful link between nerve signals, gut hormones, and GI bacteria.
A definite conclusion is that this ‘crosstalk’ between the gut and the brain is leading many to look at disease in a new way. Those researchers studying depressive symptoms, as well as Parkinson’s and Alzheimer’s disease, along with many other conditions, are starting to look at what is happening in the gut of the patient, and some exciting information is coming to light. It seems that good nutrition and healthy gut flora have a remarkable impact on our mental and physical well-being. Much of what was thought to be controlled by the brain, is also closely linked to what’s happening in the gut.
How this understanding can address GI tract issues
With this close connection between the gut and the brain, and as the ‘two brains’ talk to each other, it seems that therapies that help the one will help the other. For example, if you have GI tract disorders, you’ll be helped with psychological interventions (or antidepressants if you are determined to go the drug route).
The following treatments have been found to assist:
- Relaxation therapy
By learning how to relax and manage stress, many find that their digestive problems are greatly improved. This could involve ways of ‘switching off’ and entering a calm state – visualization, meditation, and something like listening to music can all assist in this area. This therapy also works well with cognitive behavioral therapy (CBT)
- Cognitive behavioral therapy (CBT)
It’s one thing to keep trying to change your state, but it’s more helpful if you can actually change your thoughts and the behaviors that lead to stressful emotional responses. The better you can cope with anxiety and stress, the more relaxed you’ll be.
- Gut-directed relaxation training
This is relaxation training that is focused on the GI function. It involves being conscious of the abdomen and imagining control over the functions. Some people who have experienced severe cramps swear by this technique to lessen the pain and ‘calm’ the digestive system.
With all the astonishing research that’s being conducted in the gut and the findings that show that the GI tract is in charge of much more than just digestion, looking after your whole digestive system becomes even more imperative – as does the necessity of paying attention to your ‘gut feelings’ in the future.
Read more on digestion
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Your digestive system includes the gastrointestinal (GI) tract as well as the liver, pancreas, and gallbladder. When you eat, food first enters your mouth, before passing down the esophagus into the stomach. From here, it travels through the large and small intestines, before reaching the rectum/anus. At every different stage, various enzymes, gut flora, bacteria, the blood supply, and hormones are assisting in the complex digestion process.