You may have heard of the gut-brain connection or the gut-brain axis. Books have been written about this topic. This article will explain this interaction, how it works, what it controls, and why it is important.
Picture of a brain inside a drawing of the head and neck.
What It Is.
The gut-brain connection is the communication between the central nervous system and the gastrointestinal system. These systems talk to each other. There are physical connections with ongoing signaling. The communication is through nerve connections, chemical messengers (like hormones), and the microorganisms in the gut (the microbiome). Outside of the brain, the gut has more nerve connections than anywhere else in the body.
How It Works.
The brain and gut communicate about everything in the body, including physical and emotional matters. You may sometimes experience a gut feeling or a gut-wrenching emotion in which a signal from the brain causes a physical response in the gut. Some researchers have named the gut your “second brain.”
The primary connection between the gut and brain is the vagus nerve, one of the 12 cranial nerves. This nerve relays signals from your brain to your gut and from the inside of your gut back to your brain. The brain influences GI function, while products from the gut stimulate the brain. The vagus nerve responds to conditions within the GI tract and sends motor signals from the brain to the gut.
The endocrine system is also involved in this interplay since hormone signals, such as serotonin, are produced in the gut and travel to the brain, enhancing mood.
The gut microbiome produces chemical messengers, (neurotransmitters) that can affect the brain. These neurotransmitters control feelings and emotions. Some of these chemicals are involved in mental health disorders like anxiety and depression.
Neurotransmitters
Hormones
Vagus nerve
Short-chain fatty acids
Immune cells
Tryptophan and metabolites
Neurotransmitters
Schematic of the brain and gut with an arrow representing communication between the two via hormones, nerves and neurotransmitters, immune cells, and metabolites of the microbiome.
What It Controls.
The communication between the brain and gut controls many bodily processes, including:
Hunger and fullness
Food preferences and cravings
Gut movement and digestion
Behavior and mood
Stress
Cognitive function
Immunity
This axis is also thought to be involved in numerous disorders, including:
Irritable bowel syndrome
Anxiety and depression
Food sensitivities
Chronic stress and fatigue
Gut movement disorders
Neurodevelopmental and neurodegenerative disorders
Why is This Important?
Research is finding that certain conditions may best be treated by treating our gut and manipulating our gut microbiome. As the first article in this series was entitled, our gut is our gateway to health. There is still a lot unknown, but focusing on this gut-brain communication may lead to different treatment modalities.
Several therapies include -
relaxation training, cognitive behavioral therapy, and biofeedback
as ways to manage and relieve stress and improve GI symptoms.
Other treatments focus on altering the gut microbiome with the use of
probiotics, antibiotics, and microbiome transplants. Changing the gut microbiome may improve brain health.
Picture of a drawing of the brain surrounded by healthy foods such as fruit, vegetables, and nuts. A healthy diet contributes to a healthy brain and gut.
Most important is what you can do to maintain a healthy gut to contribute to brain health. Eating a healthy, balanced, whole-food diet with many diverse plants, fiber, and omega-3 fatty acids is a great start. More on this topic next week!
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