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The gut-brain axis - how do gut and brain work together?

Gut and brain - two important organs in the human body. But what do they have to do with each other? Quite a lot! Because a healthy intestine makes for a healthy brain and vice versa.

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The gut-brain axis - how do gut and brain work together?

Gut and brain - two important organs in the human body. But what do they have to do with each other? Quite a lot! Because a healthy gut makes for a healthy brain and vice versa. In order for the two to work together, there is what is known as the gut-brain axis. How does the communication between the two organs work? And what happens when one communication pathway does not function properly?

You can find out this and much more in our latest article on the gut-brain axis.

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Table of contents

• What is the gut-brain-axis?
• How does communication between the gut and brain work?
• Why is the gut-brain axis so important?
• What happens when it is disturbed?
• How can I strengthen the gut-brain axis naturally?
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What is the gut-brain axis?

Figuratively, the gut-brain axis can be thought of as a long connecting tube that transports stimuli, signals and messenger substances between the brain and the gut. At the same time, the axis ensures the maintenance of self-regulation in the body.

As early as ancient Greece, physicians recognized the interconnectedness of the two organs and studied their interdependence. This led to the realization that it is not enough to look at just one organ system when diagnosing a disease1.

Today, it is known that the occurrence of gastrointestinal symptoms is related to diseases of the central nervous system. An example of this is Parkinson's disease, in which intestinal symptoms occur before neurological signs.

What is the communication between the gut and the brain?

One of the main branches of communication between the brain and the intestines is the so-called vagus nerve. This is composed of 80% afferent, or influx, fibers and 20% efferent, or efferent, fibers2. The difference between the fibers is that afferent nerves transport signals from the body to the nerve cells, whereas efferent nerves act in the opposite way. Through this process, metabolic products are ultimately sent from the gut toward the central nervous system, from where they are transmitted to the appropriate nerve pathways.
If the function of the vagus nerve is disturbed, there may be health consequences. One factor that can contribute to this is stress, for example. Its negative effect on the gastrointestinal tract and the microbiome promotes the development of diseases such as irritable bowel syndrome or chronic inflammatory bowel diseases.

Another way of communication is through neurotransmitters. Researchers have discovered that intestinal bacteria produce neurotransmitters, but can also influence them and thus use them as signaling pathways. Well-known examples include histamine, steroids, and gasotransmitters3.

Why is the gut-brain axis so important?

As mentioned at the beginning, the gut-brain axis is important for establishing homeostasis, the maintenance of physiological balance in the body. This includes, among other things, the regulation of body temperature, blood ph, hormone levels or even reflexes.

Also in terms of general health, the communication between the intestine and the brain has relevant tasks. The intestine alone is one of the most important organs of the human body. On the one hand, almost all microorganisms in the human body are located there. On the other hand, almost all immune cells of the human body are also located there. In order to protect the body from pathogens, it is advisable to promote the diversity of intestinal bacteria through diet. Because as we know, it is mainly the intestine that sends most of the signals to the brain. If this is now impaired due to poor nutrition, genetic changes or pathogens, this also has a negative impact on our cognitive performance.

What happens when there is a disorder?

There are various reasons why a disturbance of the gut-brain axis can occur. On the one hand, reduced food intake in old age is one of the main reasons for the occurrence of cognitive decline in old age. The reasons for nutritional deficiency vary and, in addition to diseases that are already occurring, may include lower energy metabolism, prolonged sensation of satiety, altered performance in chewing, or even reduced sensation of hunger. This is, for example, one of the reasons for the development of Alzheimer's disease in old age. This is because deteriorating nutrition leads to a disturbance in the function of the gastrointestinal tract, which affects the central nervous system and thus causes disorders.
However, irritable bowel syndrome is the most common disease indicating a disturbance between the intestine and the brain. Symptoms that point to this are primarily chronic abdominal pain, diarrhea, constipation or flatulence. Triggers for this include stress, which can inhibit the function of the vagus nerve, which has a negative effect on the gastrointestinal tract.

How can I strengthen the gut-brain axis naturally?

It doesn't take much to strengthen the gut-brain axis. One way is to activate the parasympathetic nervous system, the part of the nervous system responsible for controlling rest and recovery. This is also better known as the rest-and-digest system and is important for normal digestion and rest. Excessive stress, as well as an overly activated adrenaline system, contributes to deteriorating gut health and affects mood. For this purpose, it is advisable to actively relax. This can be achieved, among other things, through targeted breathing, relaxation or stretching exercises.
But this is not the only way. As is so often the case, nutrition plays a major role. In the case of the gut-brain axis, psychobiotics (here: prebiotics) and probiotics have a health-promoting effect on the gut and brain. Especially when it comes to cognitive health. Unsaturated fatty acids, which include omega-3 fatty acids, are also repeatedly recommended. In Alzheimer's disease, for example, probiotic foods help rebuild the diversity of intestinal microbes and curb the progression of the disease. But vitamins such as folate or vitamin E also have an anti-inflammatory effect and can reduce oxidative damage4. The key is a balanced and nutrient-rich diet. Those who eat a diet exclusively high in sugar and low in fiber are not only harming their intestinal health, but are also putting themselves at risk for impaired mental function.

Support by MITOcare

If the gut-brain axis shows one thing, it's how important the health of both organs is. A weakened intestine, for example, plays its direct part in weakening the nervous system. Conversely, stress hormones have a negative effect on the gastrointestinal tract. In addition to relaxation exercises and food, it is worthwhile to resort to additional support in the form of dietary supplements to strengthen both the intestines and the brain.
1 Margolis, K. G., Cryan, J. F., & Mayer, E. A. (2021). The Microbiota-Gut-Brain Axis: From Motility to Mood. Gastroenterology, 160(5), 1486–1501.

2 Bonaz, B., Bazin, T., & Pellissier, S. (2018). The Vagus Nerve at the Interface of the Microbiota-Gut-Brain Axis. Frontiers in neuroscience, 12, 49.

3 Strandwitz P. (2018). Neurotransmitter modulation by the gut microbiota. Brain research, 1693(Pt B), 128–133.

4 Thangaleela, S., Sivamaruthi, B. S., Kesika, P., & Chaiyasut, C. (2022). Role of Probiotics and Diet in the Management of Neurological Diseases and Mood States: A Review. Microorganisms, 10(11), 2268.