• Dr. Cirelli

The Surprising Connection Between Gut Bacteria And Mental Health


If you've ever given a big presentation, there's no doubt that you've experienced the “butterflies in my stomach” feeling. Or, perhaps, you've made a major life decision and you had a "gut feeling" about it. Have you ever wondered why so many of these sayings involve our brains and stomach? The answer lies in something called the gut-brain connection.

As it turns out, the butterflies in your stomach aren’t such a coincidence. In fact, as scientists start to learn more about the human gut, also known as the microbiome, the more it’s clear that it really is our “second brain.”

As you're probably already aware, an imbalance of bacteria in our gut is linked to serious conditions and diseases such as IBS, Crohn’s, celiac disease, thyroid disease and many more. As it turns out, science is also discovering the connection between our gut and our emotions is just as strong



What Is the Gut-Brain Connection?

The bacteria in our gut plays a major role in our overall health and function. It's responsible for everyday functions like digesting food and absorbing the nutrients from it.


The connection between the gut and brain works in a “bi-directional manner"--meaning the gut sends signals to the brain and the brain sends signals to the gut. Irritation in the gut sends signals to the brain via the central nervous system (CNS) that triggers mood changes, while mood changes send signals from the brain to the gut.


As more research emerges, evidence shows our gut is home to the enteric nervous system (ENS). The ENS is a collection of neurons and glial cells that is sometimes referred to as the “small brain” of the gut. It consists of nerve networks that run from your esophagus to your anus and connect directly to the entire digestive system. Completely separated from our CNS, the ENS is made up of two layers with more than 100 million nerve cells. Collectively, our ENS houses more nerve cells than our spinal cord.


The cells in our gut have many functions such as controlling blood flow and helping with digestion of our food. These cells are also responsible for allowing us to “feel” what’s happening inside the gut, since this second brain is behind the mechanics of food digestion.

While this second "brain" in the gut does not get involved in things like thought processes and reasoning, research shows that it does control some behavior on its own. Scientists believe this developed to make digestion more efficient in the body. Essentially, this allows us to handle things closer to the source and does not require the body process the entire digestion process through the CNS.

Due to the fact that the brain is very complex, scientists are not solely convinced that it was designed merely to aid in digestion. So, while it isn’t capable of thoughts, it does “talk” to the brain in major ways.

Impact on Depression

Current research on the microbiome demonstrates that it plays a key role in depression. The balance of bacteria in the gut has proved to benefit mental health by enhancing the microbiome content in our digestive system.


Research indicates a healthy balance of bacteria in the gut helps transmit signals through pathways that are involved in the formation of brain neurons and the behavioral control centers in the brain. Additionally, research reveals inflammation in the gut can affect the brain and how one thinks--which helps explain why more than 20 percent of all irritable bowel syndrome (IBS) patients show signs of depressed behavior.


The IBS and depression connection was further illustrated when the use of probiotics was studied on patients with IBS. Researchers discovered twice as many patients had improvement in their depression symptoms when they took a probiotic as compared to patients who took a placebo.

Further studies identified patients with inflammatory diseases are more prone to depression as well. Researchers have hypothesized that this is because of a dysregulation in the pathways involved in the gut-brain axis. This research shows that inflammation leads to depression, and the main source of this inflammation is the imbalance in our gut microbiome.


Impact on Anxiety

Often called the "feel good hormone," serotonin acts as both a hormone and a neurotransmitter in the body. Serotonin plays a pivotal role in regulating mood and contributing to our mental well-being.


Although serotonin is well known as a brain chemical, it is estimated that 90 percent of the body's serotonin is made in the digestive tract. Altered levels of serotonin have been linked to diseases such as low mood, depression, anxiety, autism, IBS, cardiovascular disease, and osteoporosis.


Serotonin is produced in the digestive tract by structures called enterochromaffin (EC) cells and also by particular types of immune cells and neurons. Research has demonstrated that those individuals with an imbalance in their gut bacteria, can produce up to 60 percent less serotonin than those with a properly balanced gut microbiome. Research also indicates that, by balancing the gut microbes, the serotonin levels increased. This illustrates that the deficit in serotonin can be reversed and that EC cells depend directly on bacteria to make serotonin.


Natural Ways to Improve Your Gut-Brain Connection

While there is still more research that needs to be conducted on our microbiome and how it connects to our overall health, there are a few things you can do in the meantime to improve your gut-brain connection:


1. Get your microbiome tested

The first step to improving your gut health is to get tested. By measuring the balance of good and bad bacteria in your gut, you can get a good idea where to start. At Total Body Health Functional Medicine, we use the latest lab tests to get a complete picture of your overall gut health. Not only are we able to measure the balance of bacteria in your gut, but we can also identify any parasites, fungi, or yeast that have overgrown in your digestive tract, the amount of inflammation in your gut, and the functions of your liver, pancreas, and gallbladder.

2. Eat probiotic rich foods and take probioticsupplements

Eating probiotic-rich foods like sauerkraut kimchi, kefir, and kombucha, can also help your gut and mood improve. Probiotics help support the good bacteria that line your gut and are responsible for nutrient absorption, digestion, and boosting your immune system.


3. Swear Off Gluten


A majority of people who limit the amount of gluten in their diets notice positive effects on both their moods as well as their gut health. The good news is that there is a wide variety of tasty gluten-free alternatives that are now available in every grocery store.


4. Avoid Processed Foods

Research shows that a whole food-based diet contributes to a more diverse microbiome than one consisting of mostly refined and processed foods. These refined and processed foods contribute to inflammation in our gut and bodies and can wreak havoc on our health. The added sugar found in these foods, often disguised as different types of artificial sweeteners, are responsible for health conditions such as obesity, Type 2 diabetes, and migraines.

At Total Body Health Functional Medicine, we’ve helped hundreds of patients overcome gut issues and have seen the tremendously positive impact it had on their health. If you’d like one-on-one support and a personalized plan to help you do the same, check out our website and schedule your FREE discovery call to get started.

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