How the Gut Biome Affects the Brain

You know that gut feeling that you get? It might be an actual thing.

There is an important relationship between gut bacteria and your mood; what you eat can affect how your brain works.

You have over 100 trillion microorganisms in your gut; that’s 10x the amount of actual cells in your body. Those bacteria have a lot to do with how your body responds to things. Your gut biomes are critical to your nervous system and your immune system development. They have a direct line of communication with the brain, and it all has to do with something called the gut-brain axis.

The gut-brain axis is essentially the line of communication between the gut and the brain, which largely determines your gut health, as well as our overall brain health and function, including your moods.

Let’s go over three things that dictate how the brain and gut communicate…

Introducing the Vagus Nerve, Gut Brain Axis and Enteric Nervous System…

The vagus nerve is a major nerve that runs from the base of your brain all the way down your spine, through you thorax, and into your abdomen. Essentially, it controls almost all organ function down from your neck to the second part of your transverse colon. That means that the vagus nerve is automatically regulating all of the autonomous function of the organs there. It’s what’s causing you to breath, sweat, talk, etc. You can think of it as a major freeway connecting the brain and the gut.

The enteric nervous system is extremely interesting; it’s essentially your second brain. It has a system of about 200 to 600 million neurons in the gut. They have their own ability to be motor neurons and dictate what the gut does, outside of the brain’s control. To put this into a little more perspective, if your stomach or your gut recognizes something, it has the ability to operate completely autonomously from the brain. So, you have your central nervous system which is what your brain and whole body are run by, and then we have the ENS – enteric nervous system. A system that operates completely separate from the brain and calls its own shots.

This basically means that the gut has the ability to influence its own activity, but also the activity of the rest of our body, because it still communicates with the brain which leads me to the next talking point.

The gut brain axis is a bidirectional communication between the gut and the brain, it’s the direct communication. Studies are beginning to show that there’s a strong link between the emotional/cognitive effects, and the overall peripheral nervous effects of the gut. This all has to do with the gut brain axis.

We’re starting to see some strong evidence of the gut’s performance affecting the brain’s performance. Between the vagus nerve, gut brain axis, and the enteric nervous system. This gives you a trifecta that is almost entirely dictating what your body does, based on what goes in your gut.

The science on this is interesting…

There’s an intriguing study that you’re likely to find referenced everywhere if you start looking at the enteric nervous system. The study took three groups of mice, which were all placed under some form of stress. In this case, they took baby mice and separated them from their mothers.

The first group of mice was completely germ free, they had no gut bacteria whatsoever, and they were left in a completely sterile environment. The second group was a normal group of mice with a normal functioning gut biome. This group was not kept in a sterile environment. The third group of mice was another normal group of mice that was not separated from their mothers. There was no stress induced on the third group at all.

What they were looking at was what happens to the brain when the gut biome are affected and they’re stressed. What’s interesting is, when the first group of mice had stress induced upon them, they found that there was an increase in corticosterone and the stress hormones. But, there was no change in depression or anxiety. The next group, when stress induced, saw an instance of depression and anxiety, and it had to do with the gut microbiome. The third group saw no change at all, because they didn’t induce stress on them.

Then, they took it a step further…

From this study, it’s easy to conclude that there’s definitely an effect on the gut microbiome and mood, but they wanted to see how far they could push this. So, they took the germ free sterile group and they introduced them and exposed them to the gut bacteria from the other group. And then, they stressed them again. Guess what? That group, now that they had the gut bacteria, did see symptoms of depression and anxiety. Confirming that the link between the gut microbiome and stress can definitely end up playing a role in how our guts and brains communicate.


So, what can you do to start taking control of your brain health via your gut health?

Get your probiotics in! Whether it’s from probiotic foods, or probiotic supplements. Probiotics increase something called GABA, which stands for gamma-aminobutyric acid. It’s a big component of your brain’s calming ability. It’s been shown to promote calmness in the brain, and has been shown to increase when we consume probiotics.
Additionally, good gut bacteria also helps the brains receptiveness to GABA in the first place. This is one of the strongest links to feeling good and solving mood issues that take place when you’re stressed out.

Although it’s not the end all be all, it’s definitely something to start looking into and understanding how powerful the gut really is when it comes to dictating what our brains do!