Can what’s going on in our gut affect our brain?

Updated: Jun 21, 2019

Guest post by Heather Lillico


It sounds straight out of a sci-fi movie doesn’t it… the little bacteria living in our intestines are controlling things elsewhere in our body. Well, believe it! More and more research is showing that microorganisms in our gut can communicate with our brain and therefore affect our behaviour.


How does this happen exactly?

We have over 1 kg of bacteria in our gut, with about 1000 known species and 5000 different strains. Different bacteria perform different functions in the gut. Some help balance blood sugar, some play a role in immune health, and others play a role in our mental health.

The main connection between our bellies and our brains is through the vagus nerve. Associated with the rest and digest side of our nervous system, it starts in the brain and spreads out, eventually heading down to the abdomen. This communication superhighway is bi-directional, meaning the bacteria in the gut can stimulate this nerve and causes changes in the brain, and that signals from the top down can influence our gut. Have you ever felt nervous and had butterflies in your stomach? That’s your thoughts and emotions influencing your bowels in a very physical way. Wild stuff! Research has shown this connection can be valuable for mood, as stimulating the vagus nerve can help depression (https://www.scientificamerican.com/article/gut-second-brain/).

Also certain strains of bacteria can make neurotransmitters, which are chemical signals that let parts of the body “talk” to each other. Bacteria are able to manufacture serotonin and dopamine, our feel good chemicals. They can also make GABA, a relaxing neurotransmitter that can help reduce anxiety. Normally these neurotransmitters are made in the brain, and it’s unlikely the ones made in the gut can cross the blood-brain barrier because that’s a pretty strict body guard. Instead, the ones made in the gut act locally on what’s called the enteric nervous system, a whole network of nerves that govern digestive activities (https://www.gastro.theclinics.com/article/S0889-8553(16)30082-6/pdf).

There is evidence though that certain compounds made in the gut can get into the bloodstream and then the brain to affect our stress hormones. Since this relationship is bi-directional, stress also has a big impact on the gut. People who are stressed have less good bacteria in their gut, and less variety too (https://www.gastro.theclinics.com/article/S0889-8553(16)30082-6/pdf).


How can we maximize this relationship?

Simply put, the bacteria in our gut do great things for our mood and our brain. To keep them in tip top shape, here are my suggestions!


Focus on fermented foods

These foods contain bacteria and should be eaten daily keep our colonies healthy. Without supplies of good bacteria to protect us, the bad guys can take over and lead to immune issues and conditions like leaky gut. Foods like kimchi, kombucha, sauerkraut, and coconut yogurt are good bets!


Eat foods containing prebiotics

Prebiotics are what feed the good bacteria in our guts. They come from a wide variety of fresh fruits and vegetables and whole grains. Good sources include garlic, onions, cruciferous vegetables like cauliflower and kale, and grains like wheat, oats and rye.


Chill out during mealtimes

In order to activate the vagus nerve we need to be in a calm, quiet space. Prior to mealtimes take some deep belly breaths to encourage relaxation. Also remove any distractions such as televisions or phones…sorry Instagram, you’ll have to wait!


Those are just a few tips for maximizing the connection between the gut and the brain. The relationship is so complex and more research is shedding light on just how important this connection is. I rarely see someone in my practice who has mood issues NOT accompanied by digestive problems. The two really go hand in hand, so remember to feed the gut to help the brain!

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