Demystifying the Gut/Brain Connection


Does your head feel foggy? Do you wake up inexplicably tired? Do you struggle with mood imbalance for seemingly no real reason? The root cause may be in a place you’d never think to look: the gut. You might be thinking, “Isn’t all of this a brain issue?” It certainly is, but scientists are becoming more and more convinced that there is an incredibly complex connection between your gut and your brain. In other words, if something is off with your gut health, it can actually affect how well your brain functions.

Health experts call this the “gut/brain connection,” and it may be at the root of some mysterious health issues that have baffled health experts for years. Today we examine this connection: how the gut and the brain communicate and how this could be a hopeful discovery for your health. We will also look at practical steps you can take to improve your gut health, which could have a positive overall effect on your brain.


Article At-A-Glance:

  • The Gut/Brain connection is a mysterious network that scientists are only beginning to understand.
  • The implications of the gut/brain connection could create new avenues for improving brain health.
  • The gut microbiome plays a hugely important role in immunity as well as brain function.
  • Gut health plays an important role in neurotransmitter production, regulating inflammation, and communicating with the human stress response.
  • There are many ways you can boost your gut health, such as taking a probiotic/prebiotic supplement or consuming fermented foods.
  • In general, avoiding high-fat diets, animal products and excessive antibiotics will help ensure good digestive health.


How the Microbiome Plays A Role

A lot of the gut/brain discussion centers around the environment inside your intestine called the gut microbiome. You may not realize it, but there are trillions of microorganisms that live inside your digestive tract. These bacteria affect many of your bodily functions and help assist in digesting food and synthesizing nutrients from your diet (source). You may think of bacteria as a bad thing–and some bacteria do cause disease–but what you might not realize is that the majority of bacteria is positive and even necessary for your health (source).

You might be wondering, what does this have to do with brain function? Surprisingly, a lot. The balance of your microbiome is extremely important to your health. A good balance of positive bacteria can help regulate positive brain function. A gut microbiome that is out of balance can lead to major dysfunction in the brain that can affect your mood, cognition and stress levels.

So, how does this work exactly? How can it be that tiny bacteria in your gut could affect the way you think, feel and act? Well first, it’s important to note that your gut health has a major impact on your immune system. According to Dan Peterson, assistant professor at Johns Hopkins School of Medicine, “A huge proportion of your immune system is in your GI tract (source).” He goes on to say that, “the immune system is inside your body, and bacteria are outside your body–and yet they interact.” Some bacteria that live in the lining of the intestine actually secrete large amounts of antibodies (immune protectors) into the gut. What all of this means is that even though bacteria are technically foreign elements, they actually play a vital role in keeping you healthy.

So what happens when these bacteria aren’t able to do their job? That’s where the brain issues come in. If there’s an overgrowth of bacteria or your intestines are too permeable (sometimes called ‘leaky gut’), then it could lead to systemic nervous system inflammation (source). This is a bad thing, and it can create cognitive issues such as mood imbalance, brain fog, fatigue, and headaches (source).



Neurotransmitters and the Gut

But inflammation isn’t the only issue at play. Another reason why the gut and brain are so connected is because the gut is the storehouse for a massive percentage of your neurotransmitters. You’ve probably heard the term neurotransmitter before in reference to mood (and especially pharmaceuticals.) In a general sense, neurotransmitters are chemicals that send messages in your brain. Part of the reason why they’re important is because neurotransmitters can influence your feelings and emotions. Serotonin is an important neurotransmitter that helps influence your feelings of happiness as well as your body clock (source). While serotonin is most associated with the brain, an estimated 90% of serotonin is manufactured in your gut. Therefore if the gut isn’t able to function properly, it could exert a potential negative effect on your mood. From this you can see why digestive health and emotional health may be interconnected (source).

Serotonin isn’t the only important neurotransmitter found in the gut. Your gut microbes also create a neurotransmitter called GABA, which stands for gamma-aminobutyric acid. What does GABA do? GABA is an inhibitory neurotransmitter, which just means that it blocks or slows activity in the nervous system (source). When GABA connects to a receptor in your brain, it creates a calming effect. This can help soothe anxious thoughts, fearfulness or stress. It may also play a role in helping support healthy sleep function.

As you can see, part of the gut/brain connection lies in the GI tract’s responsibility for producing neurochemicals for the brain. This is key for the brain to function normally. But that’s not all: the gut is also connected to a network that is responsible for your stress response. It’s called the HPA axis.



The Gut and HPA Axis

If you feel stressed out all of the time, deal with unrefreshing sleep, have trouble with persistent fatigue, there may be something off with your HPA axis. What is that? It stands for the Hypothalamic-Pituitary-Adrenal axis. Together this network handles stress in your body, whether emotional, physical or mental. When you start to experience stress, your HPA axis kicks into gear. It does this in part by secreting stress hormones, such as adrenaline and cortisol. When it functions well, your HPA axis handles stress appropriately. When the HPA isn’t functioning, it can lead to a host of issues, such as fatigue, brain fog, insomnia, cognitive dysfunction and others.

In recent years, researchers have come to understand that the gut microbiome is one of the key regulators of the HPA axis (source). In fact, the microbes living in our gut interact with our HPA axis continuously, and they exert an influence very early in life (source). Some studies with animals have shown that a lack of appropriate gut bacteria can lead to an overactive HPA axis. Essentially, what that means is that there may be a connection between an unhealthy gut biome and an overly stressed nervous system. Interestingly, researchers also found that positively adjusting the gut microbiome in animals also regulated and balanced the HPA axis, but only in young animals still in a developmental phase.

It’s almost perplexing to think that your thoughts and actions could be influenced by the bacteria in your gut. Repeatedly, we have been told that issues like stress and mood imbalance are a product of chemical imbalance in the brain. However, the study of the microbiome and its influence on emotions is the fastest growing area of study for psychiatric issues (source).



The Gut is Your “Second Brain”

This connection is so strong in fact, that many scientists now refer to the gut as the ‘second brain’ because of its control and influence over our emotions (source). This is because of a network inside your GI tract called the Enteric Nervous System (ENS for short.) Your ENS is a huge mesh-like connection of neurons that are embedded into the wall of your digestive tract. This is the communication system responsible for sending and receiving messages from the HPA axis. It is also the network responsible for creating and moving your neurotransmitters (source).

In short, the gut/brain connection is not only complex, the line between the two is becoming more blurred as research develops (source). The more we come to understand about the importance of the gut and the microbiome, the more critical digestive health becomes. The good news about our gut is that there are practical steps we can take to improve our digestive health. Our microbiome is highly responsive to the food we eat and the new bacteria we introduce. In this next section, we will talk about further ways that you can help improve your gut health.



Ways You Can Improve Your Gut Health: Probiotics

More and more, probiotics have become a mainstream part of culture. We’re constantly reminded to consume probiotic-rich food and drink, yet most of us don’t actually know why we need them. The simple way to explain it is that probiotics are a form of positive bacteria that can influence your microbiome. By adding probiotics, you can help encourage balance in your gut bacteria, which as we’ve seen, may have a positive impact on your brain health (source).



How To Increase Your Probiotic Intake

So how do you get probiotics? There are actually a few ways. Broadly speaking, you can increase your probiotic intake through your diet or through supplements. In terms of diet, one of the best ways to add probiotics is through fermented or cultured foods. Fermentation is an ancient process of food preservation (source). If your grandmother ever canned vegetables, for instance, that is an example of fermentation. Chemically, fermentation is a process where yeast and bacteria turn carbs into alcohol or acids (source). Why does that matter? Because this process creates a breeding ground for positive bacteria that may boost your gut health.

So, what are some good examples of fermented foods? Here is a list: Yogurt, Cheese, Tempeh, Miso, Kimchi, Sauerkraut, Kefir, Kombucha tea, Beer, Wine, Olives and Sourdough Bread (source).

The other most common way to get your probiotics is through a dietary supplement. There are many of them on the market, and it can be somewhat confusing to know which one works best. Here are some general guidelines for choosing a probiotic.

  • Normally, probiotics are measured in CFU’s (colony-forming units.) Research shows that typically higher doses tend to yield the best results (source).
  • Although probiotics in general are good for your health, certain strains of probiotics are more useful for specific health issues. A review of 38 studies found that the following strains were beneficial for brain health, helping to support mood and boost cognitive function: Bifidobacterium longum, Bifidobacterium breve, Bifidobacterium infantis, Lactobacillus helveticus, and Lactobacillus rhamnosus (source).



Ways You Can Improve Your Gut Health: Prebiotics

While probiotics get the most press, prebiotics may be just as important. Why? Because prebiotics essentially feed probiotics and help keep them alive. Scientific research has also found that prebiotics help cultivate the friendly bacteria that is already in the GI tract (source). They work to stimulate the growth of beneficial gut microbes and aid in overall digestive health. Usually prebiotics are a type of dietary fiber, but not all fiber is a prebiotic. Prebiotics are a special kind of fiber that can be metabolized by gut microbes (source).

So, how do you get prebiotics? One way is through diet. Some examples include: chicory root, apples, bananas, asparagus, onions, leeks, and garlic. However, the prebiotic content in these foods may be relatively low (source). A potentially easier way to get prebiotics is by choosing a probiotic supplement that already has them built in. Usually the label will show if the probiotic contains some kind of prebiotic formula.



Other Ways To Cultivate Gut Health

 There are other guidelines you can follow to help boost your gut health. Here are some general lifestyle tips that can be beneficial.

  • Limit Fats–In general, avoiding fried foods and excessive oils will encourage the growth of good bacteria in your gut.
  • Avoid Animal Foods–When possible, it would be good to stay away from dairy or red meat. It doesn’t mean you have to be a T-totaller; however, these foods can increase the growth of ‘bad bacteria’ and lower the amount of good bacteria.
  • Avoid Excessive Antibiotics–Antibiotics are useful and at times necessary; however, it is important to note that they kill both good and bad bacteria (source). The good news is that probiotics can also help replenish good bacteria wiped about by antibiotics (source).

In general, these guidelines should help boost your positive gut bacteria, which in turn can help not just your brain function, but your overall immunity. The field of digestive health is an area of growing research, and experts are only beginning to understand the dynamics between the gut and the brain. While these suggestions are a good starting point, there is more to the picture of digestive health–and more you can do. Stay up to date here at to learn more about your gut and how taking care of it can help boost your brain function.

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