Many sufferers report that stress can worsen the symptoms of irritable bowel syndrome. Certain situations, feelings, and thoughts can cause abdominal pain, bloating, or increase or decrease constipation or diarrhea. So there exists a connection between IBS and mental well-being.
To better control IBS symptoms, it is important to understand how the brain and gut signaling work. In this article, you will learn all about these signaling pathways and how stress can affect IBS.
What does the gut-brain axis mean?
Our gut-brain (enteric nervous system) and our parasympathetic and sympathetic nervous system form our autonomic nervous system. The gut-brain is “autonomous” because it works independently from the brain. Thus, we cannot control our intestine directly, only involuntarily. Internal states of tension and stress are important influencing factors on the gut-brain.
We often talk about a gut feeling when it comes to intuitive decisions or the perception of moods. Our gut feeling can also provide clues as to whether we feel stressed or relaxed. On the one hand, the abdomen can catch the external signals (e.g. stress) from the body and report them back to the brain. On the other hand, the gut can also affect our mood and create additional stress. The mutual influence between the internal organs and the brain happens via nerves, hormones, and special messenger substances, making the so-called gut-brain axis. Our gut-brain is connected to the brain in our heads via this axis.
If disorders occur with the gut-brain, the mobility of the intestine (motility) may be disturbed. Today, it is believed that, among other factors, dysmotility (when the muscles of the intestinal wall do not function properly) is an important cause of IBS.
What interactions exist between stress and the gut-brain?
Our gut-brain controls our digestive system’s activity, but the gut-brain does not act quite independently of the rest of the body. Rather, it is in constant communication with the rest of the autonomic nervous system. The autonomic nervous system is also known as the vegetative nervous system. It consists of two different systems that are supposed to work together harmoniously:
- The parasympathetic nervous system
- The sympathetic nervous system
Both directly affect the function of digestion and communicate with the gut-brain. The distinction between these two nervous systems is easier if you recall the processes that control them.
How does the parasympathetic nervous system affect digestion?
The parasympathetic nervous system helps us relax and digest. It is responsible for the processes that help us to feel relaxed and calm. The parasympathetic nervous system is active when our brain tells us that we are not under duress and there is no danger. When the parasympathetic nervous system is active, our body stops to sleep, eat, digest and relax. The parasympathetic nervous system is very important for the body’s regenerative processes.
How does the sympathetic nervous system affect my gut?
The sympathetic nervous system becomes active in so-called “fight-or-flight” situations, i.e. moments of tension, defense, and flight. It activates the whole body. Our body releases the stress hormones adrenaline and cortisol, and our liver provides our muscles with a lot of blood sugar for energy.
The sympathetic nervous system causes an increase in heart rate, blood pressure, breathing, and muscle tension, and sometimes a contraction of the bladder. That is the reason why sayings like “being scared sh%tless” have become commonplace.
What is the function of the sympathetic nervous system?
The sympathetic nervous system has changed in the course of evolution: It was particularly important when we encountered life-threatening danger (such as an encounter with a tiger). In such situations, it is important to have as much energy as possible to be able to react optimally to the threat with a fight or flight response. But acute life-threatening situations like these are rare in our times.
If we were lost in thought, busy with our cell phone, and accidentally crossed against a red light while a car was rushing towards us at high speed, we would respond the way our ancestors did with a stress response and physical activation to avoid the imminent danger. Our body would react immediately to avert the danger.
What happens when the autonomic nervous system gets out of whack?
Conflicts with family members, traffic congestion, family visits, exams, presentations, job interviews, time pressure, and unpaid bills are situations or circumstances to which we also respond with stress. Even though these stressors do not require a sudden physical effort, the sympathetic nerve is activated to provide as much energy as possible, which is then not consumed.
This excess energy can be one of the reasons why chronically stressed people have many different physical symptoms, such as muscle tension, headaches, neck pain, an increased heart rate (tachycardia), or gastrointestinal problems.
People affected with IBS often also have a low activation threshold for external stimuli. In other words, people with IBS rate stimuli more quickly as relevant, respond faster, and can be more easily stressed by things than others. This stress can be manifested by physical symptoms such as increased stool frequency and diarrhea. During periods of rest, such as at night or on vacation, symptoms typically subside.
The experience of stress can ultimately lead to nervous system dysregulation (when there is an imbalance between the activating and calming part of the nervous system). The communication between the different parts of the nervous system is disturbed, and digestion reacts to the external influences and stress more strongly than it should. Thus, irritable bowel symptoms are exacerbated by stress via the nervous system.
How can IBS trigger stress?
Today, we know that the gut can send signals directly to the brain. This happens via
- Nerves (especially the vagus nerve)
- Gut hormones
- Excretions of the intestinal bacteria of our intestinal flora, i.e. our microbiome (microbial metabolites)
- Special signaling substances (cytokines)
Through these different paths, stress from the tummy reaches our brain directly, which can negatively affect our thoughts, feelings, and actions. The result is additional stress.
How can stress aggravate irritable bowel symptoms?
It is hardly surprising that stress is closely related to the symptom severity of IBS. However, this does not mean that irritable bowel sufferers are only imagining their symptoms. Today, it is known that mental stress and intestinal discomfort strongly influence each other.
With IBS, micro-inflammation in the intestinal wall can be detected, which causes increased sensitivity of the intestine. As a result, intestinal symptoms are additionally perceived more strongly, which—in addition to everyday stress—causes negative stress. This mental stress in turn has a negative effect on intestinal complaints via the nervous system. A vicious circle arises. It can thus help to specifically reduce stress in the context of irritable bowel treatment, for example, through exercise or relaxation techniques.
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