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The Ins and outs of the GI system

Aug 08, 2022

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The Ins and outs of the GI system

Lets start with the Basics

What is the gut? 

Many of you have heard of the GUT. You may have heard of it called the GI system, or the GI tract, all of these are short for the gastrointestinal system. And the gastrointestinal system starts in our mouth. It goes all the way down our esophagus, to our stomach, the small intestine, the large intestine, and then out through our colon. The gastrointestinal system also contains our liver, our pancreas, and our gallbladder, and most people don't realize this. All ll of these organs need to work perfectly together to have optimal digestion. And it is important to have optimal digestion to feel our very best. And that is what we're going to talk about today.


Why is gut health so important?


Well, firstly, 60 to 80% of our immune system lives in our gut underneath our small intestine. And most people don't realize that. So when there's a disruption in the gut or the microbiome, there is a disruption in our immune system, and you may have heard those people, or you may be one of those people that is sick all the time, or just feels like you can't fight off a common cold that easily. And it could be related to your gut and not having the defense system that you need. 90% of our neurotransmitters are made in our brain. Neurotransmitters are things that send signals, and these are specific to helping with our moods like serotonin and dopamine.

These are essentially our happy neurotransmitters. They help prevent anxiety and depression. When we have an imbalanced gut, we can have issues with anxiety, depression, and mood disorders. 

Melatonin is also made in our gut. Some of it is made in our pineal gland too, but a large portion is made in our gut. So, melatonin is what helps turn on our signal to sleep. There may be sleep disruption as well. The gastrointestinal system aids in ingestion, secretion, propulsion, digestion, absorption, and defecation. And that's what keeps our bodies as well, oiled machines. 

You always hear that saying “you are what you eat”. I always think, “you are what you absorb and you digest”, right? If we're not absorbing and digesting our food, we're missing a lot of the key micronutrients that we need to properly function.

The digestive system also has its own essentially ecosystem, its protective soil known as the microbiome. You may have heard of this, and this is essentially the housekeeper of our body. 90% of the cells in our body are microbiome. The microbiome runs through and helps neutralize the bad guys, the bad bugs, and the chemicals, and prevents an overabundance of toxic chemicals called lipo polysaccharides or LPS. So it keeps our system clean and running optimally. And this is all located within the gastrointestinal system. 

By now, you  may have heard of the gut referred to as the “second brain”, and that is because of this gut-brain connection. We have something inside our gastrointestinal system called the enteric nervous system. This is consistent with over 500 million neurons that are embedded in the intestines. And they communicate with over 35 neurotransmitters throughout the day. And they send signals all day long to our brain. This is all done through one of the largest nerves called our Vagus nerve.

A lot of these neurotransmitters that I talked about, like serotonin and dopamine, are so important for helping the function of our gut, right? 

We talked about 95% of the serotonin is made in the gut bacteria and it helps us feel joyful and relaxed, but serotonin is also responsible for influencing gut motility. So if there are issues with the gut and the connection with the brain, there may be a lack of serotonin and there may be issues with motility, meaning constipation or on the other end diarrhea. These are the signals that are sent all day. Inside the gastrointestinal system will send signals to the brain to say, “Hey, make digestive enzymes, make hydrochloric acid”, -which helps with the digestion of our food. This is constant communication all day.

We already discussed how dopamine is made in the gastrointestinal system. And one of the important things is a lot of people suffer from IBS which is Irritable Bowel Syndrome. And most of those that have IBS have a very sensitive visceral hypersensitivity and it's often related to these gut nerve endings. So they'll be very sensitive to their alterations causing diarrhea, and constipation. Ths is because of this gut-brain connection.


One of the things that is so important for digestion is hydrochloric acid.

Our stomach is a very acidic environment, between one and three. And this is because it maintains the acidic environment to help break down protein and absorb minerals such as calcium, magnesium, and iron. Mucus is created by the stomach to create kind of this barrier to protect us so that this hydrochloric acid doesn't burn the lining of our stomach. So we're nice and protected by this mucin layer. Hydrochloric acid has a lot of important functions. One of them is that it helps tell the gallbladder to trigger the secretion of bile. Bile is what helps us absorb fats.

When we don't have enough hydrochloric acid, it's called Hypochloridria. And what happens when there is a lack of stomach acid is two key sphincters are not going to be signaled to close. So there is one sphincter that is located between our esophagus in our stomach, and this needs to open to allow food to go through and then close. Remember that the stomach is very acidic, so after you eat, if you have enough stomach acid, it signals that sphincter to close back up so that this food that is mixed in this acid is not going back up our esophagus and causing that burning.

With out enough stomach acid that sphincter remains open and we have acid going up, and that is what causes heartburn. And a lot of people think that heartburn is related to too much stomach acid, but it's actually from a lack of stomach acid. And we're going to discuss PPIs a little bit later that are given for heartburn often and how it's not fixing the issue. 

The second sphincter that doesn't close is between our stomach and our small intestine. And what happens to that is this sphincter doesn't open, so it's not getting the signal to push food through to our small intestine. So it kind of can sits in the stomach for longer than it should. And it can start to ferment, which causes gas and bloating and makes us feel bad. Once it pushes through the small intestine, it's been sitting there for a long time, and it ferments. So you can have foul-smelling stools. And that is all because of the lack of stomach acid.

Bile gets stuck, which causes that bile duct to get clogged and it leads to gallstones, right? So if bile is not clearing, what happens is it allows bacteria to leak back into the small intestine where it shouldn't be.  Bacteria should not be in the small intestine. 

This can lead to small intestinal, bacterial overgrowth. You may have heard of SIBO before, and this is leading us to be very bloated and feel awful, and can't tolerate foods. Bile also emulsions food and acts as a mild laxative. So we may have more constipation. We're not able to tolerate fats if we're not making enough bile, because this whole system is off.

And lastly, it's not triggering those key enzymes that we need to break down our food to properly digest them. So we're not digesting, we're not absorbing. And we're just deficient in nutrients and minerals and vitamins that we need.

Without these systems working properly it can lead to the break down of the mucin lining, Dysbiosis and utlimately leaky gut!