Over the last few years, researchers and psychologists have started paying significantly closer attention to a previously overlooked organ when it comes to mental health, the gut.
The gut is also referred to as the second brain, owing to a complex system of neurons it has called the enteric nervous system (ENS). This system is in continuous communication with the brain, and it has a strong influence on our mood, thoughts, and reaction to stress.
In 2026, there is an increasingly expanding body of research in the field of neuroscience and psychology that is showing how intertwined our digestive system and our emotional well-being actually are. This gut-brain relation is already an important component of contemporary behavioral science, and that is why most Psychology courses today contain courses on neurobiology, stress physiology, and the gut-brain axis.
We shall see why the gut is regarded as the most important partner of the brain.
What Is the Enteric Nervous System?
The enteric nervous system (ENS) is a complex system of neurons located in the linings of the digestive tract. It runs from the esophagus to the intestines.
The ENS is exceptional in the nature of its complexity. It has more than 100 million nerve cells, as compared to the spinal cord. These are neurons that govern the digestion, the gut movement, and interact with the brain.
The ENS is an independent system that can function without interference with other body systems. It is able to control the digestive process as well as react to environmental cues, even without the brain being directly fed.
But it does not work very well independently. Rather, it performs a two-way communication molecule with the brain constantly, which is known as the gut-brain axis by scientists.
The Gut–Brain Axis: A Two-Way Communication System
The brain and the gut are interconnected via a number of biological pathways, such as:
- The vagus nerve has a direct connection between the digestive system and the brain.
- Endocrine hormonal stimulation.
- Responses of the immune system that affect mood and inflammation.
- Trillions of bacteria are active in the gut.
This indicates that communication is not one-way only. The brain controls the digestion, and the gut also provides strong feedback to the brain.
Indicatively, others experience stomach upsets when they are stressed. Meanwhile, health issues of the gut may be the cause of fatigue, irritability, and mood swings.
The bidirectional communication is one of the most important issues discussed in advanced Psychology classes, in particular, in health psychology and behavioral neuroscience.
Why the Gut Is Called the “Second Brain”
The gut is also referred to as the gut, due to its production and regulation of a large number of the same neurotransmitters that affect mental states.
Serotonin, a neurotransmitter, is one of the most significant ones and is related to mood, emotional stability, and well-being.
Astoundingly, serotonin is mainly produced in the digestive system, and not the brain, in approximately 90 percent of the body.
Other significant chemicals affected by the gut activity are:
- Associated with reward and motivation is dopamine.
- GABA has a calming effect on the nervous system.
- Belong to gut bacteria and are produced by them; short-chain fatty acids are linked to the well-being of the brain.
Under healthy conditions of the gut, the chemicals assist in emotional control and clarity of thoughts. In case of the dysfunction of the gut microbiome, mood and mental processes can also be impaired.
How Gut Health Influences Mental Well-Being
The linkage of digestion to emotional health is being understood better with the help of modern research.
There are a number of psychological conditions that are now associated with gut health, and they include:
- Anxiety disorders
- Depression
- Chronic stress
- Irritable bowel syndrome (IBS)
- Fatigue and brain fog
In case of the imbalance of the gut microbiome, which may happen because of unhealthy eating, long-term stress, sleep deprivation, or antibiotics, the level of inflammation can increase. The process of inflammation may affect brain chemistry and emotion control.
Such is the reason why sometimes gut health can be improved with the result of observable changes in mood and mental clarity.
These associations have become a significant field of research since researchers in psychology and neuroscience are still trying to understand them.
Stress and the Gut: A Powerful Feedback Loop
Digestion is severely affected by stress.
The body enters the fight-or-flight mode, and blood flow is redirected from the digestive system and onto the muscles and other vital organs, which are necessary to allow the body to survive in the short term. Consequently, the rate of digestion is slowed down.
As long as the stress is chronic, this pattern will persist. In the long run, it has the ability to disturb the bacteria of the gut, modify the production of digestive enzymes, and enhance inflammation.
This creates a feedback loop:
- Stress interferes with the gut’s operation.
- The gut imbalance influences the manufacture of neurotransmitters.
- Feeling and emotional management are decreased.
- More stress is also detrimental to gut health.
This cycle is the key to understanding mental health specialists and people who want to feel good in general. The significance of psychological and physiological factors in the process of mental health support is highlighted in many modern Psychology courses.
Supporting a Healthy Gut–Brain Connection
Some simple changes in lifestyle can be helpful in enhancing the relationship between the gut-brain.
Healthy behaviors that help to maintain gut and mental health are:
- Consuming a healthy diet that is full of fiber, fruits, vegetables, and fermented foods.
- Sleeping routinely helps in digestive and hormonal balance.
- Stress management by using mindfulness, exercises, or relaxation.
- Minimizing highly processed foods that derail the gut microorganisms.
- Exercising to enhance good digestion.
These are not only beneficial to the digestive system but also to the emotional and cognitive functions.
Why the Gut–Brain Connection Matters in Modern Psychology
The increasing awareness of the enteric nervous system is transforming the way practitioners treat mental health.
Rather than considering psychological problems only as cognitive or emotional problems, researchers have come to understand that biological systems, including the gut microbiome, immune system, and nervous system, are important in psychological problems.
This holistic approach can be used to understand the reasons why mental health is an interdependent phenomenon, which requires various and linked conditions, such as lifestyle, environment, and physiology.
Students taking psychology courses tend to delve into these interdisciplinary relationships and learn more about the way the body and mind interrelate and interact with each other, but not individually.
FAQs (Frequently Asked Questions)
What is the enteric nervous system?
The enteric nervous system is a group of neurons in the digestive system that controls the digestion process and is in contact with the brain.
Why is the gut called the second brain?
Due to the presence of millions of neurons and numerous neurotransmitters that affect the regulation of mood and emotions.
Can gut health affect mental health?
Yes. It has been found that gut bacteria, inflammation, and neurotransmitter generation can be used to affect the mood, stress response, and cognitive performance.
Do Psychology courses study the gut–brain connection?
Yes. Neuroscience, behavioral biology, and the gut-brain axis have become common topics in many Psychology courses.