Dr. Shebani Sethi
speaker
159 appearances
2 recordings
1 series
first heard Feb 2025
last heard Mar 2025
Dr. Shebani Sethi’s voice in public audio — every appearance, attributed to the second.
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She would get kicked out of school all day, on the bus ride home, they'd have to stop the bus 10 times. She was terrorizing her little sister, tearing up pictures of the family, just kind of little nuts. I did testing and she didn't have any gut symptoms, but we found really high levels of bacterial overgrowth and bad bugs in her gut and yeast overgrowth.
And again, I gave her an antibiotic, an antifungal, and literally overnight, she turned into this beautiful, sweet little girl. So that made me think, oh my God, there's a whole untapped world here that we're missing of how to help people who not only have physical health issues, but also have mental health issues. So today we're gonna dive deep into the gut-brain connection.
We're gonna share some functional medicine tools that will help support your gut health and obviously your mood and mental health too. So what is this gut-brain connection exactly? Well, let's go into the science. The human brain contains approximately 100 billion neurons, brain cells. nerve cells, right? The gut also has a nervous system.
It's called the second brain, also known as the enteric nervous system. Enteric just means gut, fancy medical word. And this contains, get this, 500 million neurons. So there's five times as many neurons in your gut as in your brain. Now there's a bi-directional highway between the brain brain and the gut brain. And this is called the vagus nerve.
And it links our enteric nervous system with our brain and their central nervous system. And it's sending and receiving signals all the time. So whatever's happening in your brain, mood, stress, emotions, impacts your gut function. And whatever's happening in your gut impacts your brain function, right? Mind-body, body-mind. We talk about this. I felt sick to my stomach. I have gut feelings.
Maybe you're so nervous you had to run to the bathroom, right? This is the gut-brain connection at work. There was a study that looked at more than 1.2 million hospitalizations for irritable bowel and 4,000 hospitals.
And people with IBS or irritable bowel syndrome had three times higher risk of anxiety, two times greater risk of depression, and then two times greater risk of suicide ideation, meaning they were thinking of suicide versus the general population. Now we used to think that anxiety caused IBS. But now we know it's the other way around and a little bidirectional. So think about that.
It's not really the stress or anxiety or mental health issues that's causing irritable bowel. It's the change in the microbiome and the irritation, inflammation to the gut lining and the enteric nervous system that feeds back to the brain. It creates an irritable brain. So irritable bowel leads to an irritable brain. So before we dive any deeper, let's define the features of this gut-brain axis.
The gut, which basically we talked about, is the GI tract. It starts at your mouth and it goes to your anus. It includes esophagus, stomach, small intestine, large intestine, all the way down to the bottom. The vagus nerve is the longest nerve that comes from your brain called the cranial nerve.
It travels through the brainstem to the gut and it connects the gut to the central nervous system and it goes through the entire higher GI tract. Think about it. You've got huge amounts of gut. If you, if you laid out your small intestine flat, it would be the surface area of a tennis court. And then there's your large intestine and then your esophagus. So all that is really important.
The vagus nerve connects to other things like your heart and lungs and so forth. But this vagus nerve is a really important part of your nervous system called the parasympathetic nervous system. This is the relaxation nervous system. It also is called the autonomic nervous system or automatic nervous system.
So it's not usually under our willful control, although we can regulate it through various practices. The yogis have been doing this for centuries. It regulates involuntary sensory and motor functions. You say, I'm going to move my arms. You move your arm, but you'll go, oh, I want to digest my food. Can you please digest the food in there? Can you please regulate my heart rate?
Can you control my blood pressure? You don't really think about it. These things happen automatically. A lot of this happens through this automatic system. There's a lot of signaling that happens through this nervous system. For example, it helps control appetite. And how does it do that? Through a peptide hormone called GLP-1, right? You might've heard about this. This is...
Ozempic, Rigobi, and so forth. Manjaro, these are drugs now, quote drugs, but they're not really drugs. They're just mimicking your body's own GLP-1 at a much higher concentration. This is also known as the satiety hormone. I mean, it makes you feel full, which is why people don't eat because they take this shot and they don't feel full.
And this is also why people lose weight because they take this shot They feel full, they don't want to eat as much, and they lose weight. This is typically secreted in the lower part of the intestine, but it basically reduces your appetite and promotes satiety. And it sends a single via the vagus nerve. So this is really important, this drug, right? It's Ozempic.
So this is something your body makes. Also, there's other hormones that are regulated called CCK or cholecystokinin, peptide YY, really important. And other compounds called short-chain fatty acids. We're going to talk about why they're important. But these are made by your gut and suppress appetite by making you feel full by activating the vagus nerve. And these are things that you can regulate.
Leptin is another hormone produced in fat cells and in the gut. And it's also the feel-full hormone. There's many of these redundant pathways in your body. And it exerts its effects through the vagus nerve. This network, this gut brain, this second brain or enteric nervous system is a vast network of, like I said, almost 500 million neurons. It's embedded in the lining of the GI tract.
What's in them not only is nerve cells, but also hormonal cells, right? Enteroendocrine cells. And they're throughout the entire GI tract. And they're involved in sensing all sorts of signals, right? What nutrients you're taking in, taste, mechanical stimuli, fiber. They detect the microbes, what's going on in there. They help sense toxic compounds. So it's really a critical system.
And as I mentioned, this is called the second brain. It operates independently, but also with the brain brain, right? The central nervous system by the vagus nerve, and it controls everything, right? Gut motility, right?
Whether you're constipated or have diarrhea, enzyme secretion, digesting your food, hormone release that regulates appetite, and then mention the full hormones or the hungry hormones like ghrelin. And it also affects blood flow that aids in digestion and absorbing nutrients. So it's super important. And the microbiome consists of about 100 trillion microbes, 5,000 different species.
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