Catherine Tanaka
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THE GUT BRAIN CONNECTION: How Probiotics Can Feed Your Brain

If there was ever a call for “digestive health,” this is it!  Especially after what I’ve experienced most recently- my mood and mental clarity was significantly impacted by what my gut was doing.  I was tummy trouble super sick- yes this is my definition.

After doing more research and repopulating my intestinal flora in my gut, I have seen a significant improvement in how my tummy has been feeling but moreover, I have felt the direct correlation of my improved tummy to my improved thoughts.

Your gut is considered your “second brain”.  

And with the plethora of literature out there, there is more and more evidence to substantiate this truth.

It is because of these new scientific discoveries on the gut,  the vagus nerve, the enteric nervous system, and the amazing influence your gut microbes can have, it is no wonder what you eat feeds not only your body but can directly affect your brain.

It is all completely fascinating and if you’ve experienced gastro-upset and worked to balance the upset with probiotics or gut care, then you too can totally understand this.

What exactly is the “gut-brain connection.”

The Gut-Brain connection is very complex, and those in the medical community, nutrition science and fitness community are still learning a lot about it! And I have been doing a lot of research trying to better understand it for myself- hence this blog post share 🙂

There seem to be multiple things working together.  Things like:

  1. How the gut links to the vagus nerve to the brain;
  2. The “enteric nervous system” (A.K.A. “second brain) that helps the complex intricacies of digestion flow with little to no involvement from the actual brain;
  3. The massive amount of neurotransmitters produced by the gut;
  4. The huge part of the immune system that is in the gut, but can travel throughout the body; and,
  5. The interactions and messages sent by the gut microbes.


It is super complex, but completely amazing to think about the intricacies of it all.

I will briefly outline some of these details and share a great recipe to help you improve your gut health.

Vagus nerve

There is a nerve that runs directly from the gut to the brain.

And after reading this so far, you’ll probably get a sense of which direction 90% of the transmission is…

Not from your brain to your gut (which is what we used to think), but from your gut up to your brain!

The enteric nervous system and neurotransmitters

Would you believe that the gut has more nerves than your spinal cord?

Well believe it because it is bizarrely true!

It is because of the plethora of nerves why your gut is  referred to as the “second brain.”

And, if you think about it, controlling the complex process of digestion and gut care (i.e. digestive enzymes, absorption of nutrients, the flow of food, etc.) should probably be done mindfully as what we ingest and the balance and imbalances in my case makes a huge impact on your overall well being. Something worth considering, no?

And guess how these nerves speak to each other, and to other cells? By chemical messengers called “neurotransmitters.”

In fact, it is through these many gut neurotransmitters that have a strong effect on our mood! e.g. a whopping 95% of serotonin is made in your gut, not in your brain!  INSANE!

The immune system of the gut

Because eating and drinking is a huge portal where disease-causing critters can get into your body (like my episode), it makes total sense that much of our defense system would be located there too, right? Seventy-five percent of our immune system is in our gut!

If you didn’t’ yet know: these immune cells can move throughout the entire body and cause inflammation just about anywhere.

And if  they’re “activated” by something in the gut, they can potentially wreak havoc anywhere in the body. Including the potential to cause inflammation in the brain.

Gut microbes

Your intestinal flora: The bouquet of your friendly neighborhood gut residents. You have billions of those little guys happily living in your gut. And they do amazing things like help you digest certain foods, make certain vitamins, and even help regulate inflammation!

But more and more evidence is showing that changes in your gut microbiota can impact your mood, and even other, more serious, mental health issues.


So why should you care?

I often discuss about the mind body connection and most of us can relate to the huge discrepancy in our workouts and nutrition when our mood and mindset are out of joint.  

You should care about this information because your nutrition or supporting your gut properly could lend access and it is quite probably to, improved discipline, motivation and mood to give you access to optimizing all aspects of your health.


In walks Probiotics: what are they?

Probiotics can take the form of supplements or foods that contain beneficial bacteria in the form of live organisms.

Your intestinal tract has trillions of microbes that collectively make up the gut flora or gut we have been referring to.

When things in your gut get thrown off- whether illness or antibiotics or a virus,  introducing or increasing your probiotic dose can be of great benefit not only to your tummy troubles but to your mental clarity.


Probiotics for optimal health


Harvard Medical School recommends a daily supplementation of 1 to 10 billion CFU (Colony-forming units).  They site for tummy troubles that you can take supplements daily for two weeks to rebalance intestinal flora.


There are also many ways to improve your gut flora by adding in probiotic-rich foods to your diet.

Here are just a few great ones:

Kombucha : make sure you get real fermented kombucha that has active cultures and isnt loaded with refined sugars and just a bunch of hooey stuff.



Fermented dairy products like yogurt and kefir. Look for brands that state they contain live cultures. Avoid yogurt and kefir that contain added sugar. I prefer kefir since it contains a greater variety of cultures than yogurt and is well tolerated even by those who are lactose intolerant.


Traditional pickled vegetables of all kinds including sauerkraut and kimchi. If you buy these food products in a store, look for those labeled “unpasteurized” since heat destroys the good bacteria that supports gut flora.


Optimal health: Improve your brain health

Although there is still a lot more research that needs to be conducted on the entirety of brain and gut health, it is indisputable that there is a large correlations of efficacy of improved gut health on your mental health: your healthy gut definitely goes hand-in-hand with a healthy brain!

So, how do you fuel your brain optimally outside of probiotics?

Of course, a variety of minimally-processed, nutrient-dense foods is required, because no nutrients work alone.

But two things that you many consider eating more of are fiber and omega-3 fats. Fiber (in fruits, veggies, nuts & seeds) help to feed your awesome gut microbes. And omega-3 fats (in fatty fish, walnuts, algae, and seeds like flax, chia, and hemp) are well-know inflammation-lowering brain boosters.

Here is a simple recipe that you can use daily to support gut health!

Recipe (Gut food fibre, Brain food omega-3): Blueberry Hemp Overnight Oats

Serves 2

1 cup blueberries (fresh or frozen)

1 cup oats (gluten-free)

1 cup almond milk

1 tablespoon chia seeds

2 tablespoons hemp seeds

½ teaspoon cinnamon

1 banana, sliced

¼ cup chopped walnuts

  1.     Blend blueberries in the food processor until smooth.
  2.     Mix blueberries, oats, almond milk, chia seeds, hemp seeds in a bowl with a lid. Let set in fridge overnight.
  3.     Split into two bowls and top with cinnamon, banana, and walnuts.

Serve & enjoy!

Tip: Your gut microbes love to eat the fiber in the blueberries, oats, seeds, and nuts. Meanwhile, your brain loves the omega-3 fats in the seeds and nuts.


Fix Your Gut, Fix Your Health

Busting Belly Bugs With Bacteria


About the Author Catherine Tanaka

My name is Catherine Tanaka. I am a Personal Trainer, Transformation Coach, Yogi enthusiast and Mom of two. I am on a mission to make a difference in others happiness through fitness using the best research available to give you the best fitness hacks to make being the best version of you possible. Learn more about my one-on-one coaching or check out my Online Course - The Body Project Protocol.