Most people don’t even think that the gut and the brain are connected. I mean, you have two totally different types of doctors managing them. You go to the neurologist for your brain or psychiatrist for mental health issues, and you go to a GI for your belly. And I bet you’ve never heard your GI and neurologist say, “Hey, I think we should collaborate on this patient.” Nope, they seem worlds apart.
Yet, they are not. The gut and brain are connected in various ways. So, they are connected. Big deal, right? Well, it is a big deal because if the gut and the brain are connected, that opens up a whole new world of treatment. It means that if you are having some issues with your brain or mental health, instead of just focusing on medicating your brain, we can work on your belly and see how it can heal your brain.
So, understanding the gut-brain connection is critical. In this article, we’ll dive deep into how our brain and gut are connected. Understanding how these pieces connect could lead you to solutions you hadn’t considered.
Understanding the Basics: What is the Gut-Brain Axis?
We always start with definitions, so let’s dive into the GUT BRAIN AXIS, which is essentially the highway of communication between your gut and your brain. Trust me, you’ll be amazed by how connected they are.
The Major Players in the Gut-Brain Connection
So, we’ve got 5 key parts to the gut-brain axis, and trust me, they are major players in this complex system. There’s the Central Nervous System (basically, your brain and spine), the Enteric Nervous System (think of it as the nervous system of your gut), the Autonomic Nervous System (that’s the part in charge of those automatic responses like fight or flight, or the chill mode of rest and digest), the HPA axis (your body’s own emergency response team – consider cortisol and hormones), and lastly, your gut microbiome. These guys are like the hardworking folks in the city, making sure everything needed for communication is up and running.
How It All Ties Together
Are you catching my drift here? Your entire nervous system (we’re talking your brain, spinal cord, those autonomic reflexes, and your emergency response system) is in constant, purposeful communication with your gut nervous system and the friendly bacteria that call your belly home. This is happening ALL day, every day.
The Communication Superhighway
This isn’t just any old network. We’re talking about a massive, intricate highway of information. Your Central Nervous System acts as the central hub, while your Enteric Nervous System (that’s your gut) and Autonomic Nervous System take turns sending information back and forth. When needed, the HPA axis jumps in to add a little cortisol or other hormones into the mix. And don’t forget the microbiome, which is busy producing neurotransmitters – consider them the cars making their way along this crucial highway.
Gut and Brain: The Unbreakable Bond
Your gut and brain are constantly in conversation; they’re totally and completely linked. Once you get this, you’ll see why treating the brain without considering the gut just doesn’t make sense.
Now, let’s dive deep into how our gut and brain are connected. We understand it now from a macro view lets talk more about the connections.
First connection: Nerves
Let’s talk about the vagus nerve first. It’s the longest nerve in the body and runs from the brainstem through the chest to the abdomen, reaching various organs, including the heart, lungs, and digestive tract. So, the gut and brain are literally connected with many important stops along the way. This nerve serves as a highway of information between the brain and the belly, and they talk to each other all day.
Initial Reactions and Digestion
It starts simple. When you smell or see food, it can trigger the vagus nerve to send signals to the brain that stimulate the release of digestive enzymes and prepare the gut for the incoming meal. It also tells the brain about the nutrients around and how the microbiome is doing.
When you eat food, the vagus nerve sends signals to the brain to release hormones like ghrelin, which stimulates hunger, and leptin, which signals when you are full.
The brain tells the belly when and how fast to digest food.
Stress and the Vagus Nerve
When you experience stress, the brain can send signals via the vagus nerve to the gut to slow down digestion and divert blood flow away from the gut to other parts of the body. This is one of the reasons why people’s appetites are affected when they’re stressed.
Conversely, when the gut is inflamed, it can send signals via the vagus nerve to the brain that trigger the release of stress hormones like cortisol, which can impact mood and behavior.
The Benefits of Vagal Nerve Stimulation
And then it gets better. Vagal nerve stimulation affects mood and anxiety. Don’t believe me? Take a deep breath and see how relaxed you are. You know why? Because you just stimulated your vagal nerve, and it told your brain to relax.
Want more? The vagus nerve impacts cognitive functions, including memory and learning. Vagal stimulation can enhance cognitive performance and has been explored as a therapeutic option for conditions like Alzheimer’s disease.
Clinical Applications: Vagal nerve stimulation (VNS) is used as a treatment for epilepsy and treatment-resistant depression. It involves delivering electrical impulses to the vagus nerve to modulate brain activity and improve symptoms.
Mental Health: Studies have shown that gut-brain communication via the vagus nerve plays a significant role in mental health. Alterations in vagal signaling are associated with mood disorders such as depression and anxiety.
Neurodegenerative Diseases: Research indicates that vagal nerve activity can influence the progression of neurodegenerative diseases, providing a potential therapeutic target for conditions like Parkinson’s and Alzheimer’s diseases.
Gut Disorders: Dysregulation of vagal signaling is implicated in various gastrointestinal disorders, such as irritable bowel syndrome (IBS), highlighting the importance of maintaining healthy vagal function for overall gut health.
OK, and we are only at the vagal nerve. Let’s move on in the gut-brain connection.
Second Connection: Neurotransmitters
Now that we’ve covered nerves, let’s dive into neurotransmitters. Think of these as tiny messengers in your body that help your cells communicate with each other. Imagine them as the cars on the highway of your nervous system. Interestingly, your gut and brain use neurotransmitters to exchange messages. Some well-known neurotransmitters include serotonin, GABA, and dopamine. And guess what? They are not only made in your brain but also in your gut!
Key Neurotransmitters Made in Your Gut
It’s fascinating to learn that the tiny living things in your gut — which we call gut bacteria — actually produce a bunch of these neurotransmitters during digestion.
Let’s talk about a couple of these important neurotransmitters:
Serotonin: Did you know that approximately 90% of the body’s serotonin is produced in the gut? This crucial neurotransmitter helps regulate mood, anxiety, and happiness, earning it the nickname “the feel-good neurotransmitter.”
Gamma-Aminobutyric Acid (GABA): This neurotransmitter acts like the brain’s calm-down signal. It helps reduce feelings of anxiety and fear. Interestingly, a part of GABA’s production happens in your gut, influenced by the good bacteria living there. It’s like having a natural way to relax, right from your own gut.
Dopamine: Ever felt that satisfaction after finishing a delicious meal or crushing your morning workout? That’s dopamine at work. While it multitasks in the body, a significant portion of it comes from the gut bacteria, guiding those feelings of pleasure and reward.
Norepinephrine: This neurotransmitter helps you focus and stay alert. It’s like your body’s own natural cup of coffee, perking you up when you need to concentrate. And yes, it’s also bustling around in your gut.
Third Connection: Gut Microbiome
Now, let’s move on to the gut microbiome. If you haven’t heard by now, the gut microbiome is made up of trillions of microorganisms, including bacteria, viruses, fungi, and other organisms, that live in your intestines. So the gut microbiome we just said actually produces the neurotransmitters
But wait, there’s more—they produce other things that affect the brain, too.
Beyond Neurotransmitters: SCFAs
Short-Chain Fatty Acids (SCFAs) may not be neurotransmitters, but they play a crucial role. SCFAs like butyrate, acetate, and propionate are produced by gut bacteria. So, what do they do? SCFAs can cross the blood-brain barrier and act on various receptors in the brain, influencing neuroinflammation, neuroplasticity, and neurotransmitter release. Butyrate, in particular, has been shown to enhance brain-derived neurotrophic factor (BDNF) levels, which is basically miracle-grow for your brain.
Other chemicals
Tryptophan, indoles, phenolic compounds—it’s a long list, really. These compounds from the belly are mighty, protecting the blood-brain barrier, reducing neuroinflammation, regulating neurotransmitters, promoting neuroplasticity, and providing neuroprotection and antioxidant effects.
Leaky Gut and Brain Health
The gut microbiome also affects whether or not you have a leaky gut—and by now, you all know what that is, right? A strong gut wall ensures that harmful substances don’t get into our system and affect our brains. The bacteria in our belly are responsible for maintaining this integrity. Leaky Gut: When the gut barrier is compromised (a condition known as “leaky gut”), bacteria, toxins, and partially digested food particles can enter the bloodstream, triggering an immune response.
If these substances get into the system, they can cause inflammation and potentially cross the blood-brain barrier, leading to neuroinflammation—basically, inflammation in the brain.
Studies have shown that people with conditions like multiple sclerosis, Parkinson’s, and Alzheimer’s have a disrupted gut microbiome, which can contribute to inflammation in the brain and increased permeability of the blood-brain barrier.
The Brain-Gut Connection
Ok, we see how the gut affects the brain, but the brain also affects the gut.
When we feel stressed, anxious, or down, it doesn’t just stay in our heads. These feelings can stir up trouble in our gut, too.
Have you ever felt nauseous before giving a big presentation, or had a stomachache during a stressful time? These are not coincidences. Our brain can send signals to our gut that trigger these uncomfortable symptoms.
The Vagus Nerve: A Two-Way Street
The vagus nerve and the nervous system tell the stomach how fast or slow to move the food, and how much enzyme to secrete when it responds to stress. The (HPA) axis—your emergency system—releases cortisol during stress, which can increase leaky gut and alter the gut microbiome. Also, there are GI hormones like ghrelin and leptin, released by the brain, that regulate appetite and digestive processes. Psychological factors, including stress and emotional states, will tell the gut to make more neurotransmitters. Finally, the brain communicates with the immune system to regulate gut inflammation through the release of cytokines, which are cells that cause inflammation.
Final Note
The gut and brain are connected. This is important because if you have any mental health issues or concerns, in addition to whatever else you are doing—therapy, meds, etc.—you also need to be treating your gut. Whether you work with me and my team or find another provider that can help you, just be sure you are getting everything you need.
