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The intricate relationship between our gut and our brain, and why it matters for our mental health


Illustration of some healthy foods
Image credit: rawpixel.com (Freepik)

Case study / by Sarah Nolan


If nerves have ever caused butterflies in your stomach, or if you’ve felt like you just couldn’t stomach it, then you’ve already experienced the way that the brain and the gut are connected – but this connection is more than just butterflies. Sarah Nolan tells all.


It might not seem immediately obvious, but your brain and your gut have one of the most powerful relationships in the body. In fact, the relationship is so strong that it’s even got its own name: the Gut-Brain Axis.


This relationship can have a major influence on how we live our lives, holding the power to affect a whole host of processes within our bodies that are responsible for keeping our physical and mental health in check.


A body with two brains


Part of the reason why this relationship is so strong is because the gut and the brain share a key characteristic that not everyone is aware of.


In all likelihood, you know that the brain is a key part of our central nervous system – an extensive network of nerve cells that control most of the functions of the body and mind. But what you may not know is that the gut has its own equivalent: the enteric nervous system.


Housing around 100 million nerve cells, the enteric nervous system passes messages from the gut to the brain and the rest of the body. As this system relays messages using the same types of cells and chemicals as our brain, it’s earned itself the nickname of the body’s ‘second brain.’



A two way system: The brain controls when digestion occurs and how nutrients are distributed in the body and in turn, the gut produces compounds that influence our mood. Source: Dr Lori Shemek


Unlike the brain though, the gut’s nervous system works in tandem with many, many microbes that take up residence in our so-called gut microbiome.


Now, whenever someone mentions microbes nowadays, most people’s reaction is to run and grab the sanitiser. But we are actually more accustomed to microbes than you might think. By the age of three, each of our gut microbiomes contain about 100 trillion microbes (just for perspective, that’s this number: 100,000,000,000,000). Within this number, there are an estimated 500 million different species of bacteria, viruses, archaea and fungi that make their homes in our digestive tracts. That might sound slightly off-putting and maybe even a little scary, but our microbiome community is actually filled to the brim with microscopic helpers whose job it is to help us make the most of the food we eat and make the most of our lives.


One crucial role the microbiome plays is in the creation of chemicals called neurotransmitters. These chemicals, which the brain also creates a lot of, are important factors in how our body reacts in response to internal and external stresses. One example neurotransmitter is serotonin which plays a big part in helping us feel upbeat and positive. Although our brain manufactures some of the serotonin in our bodies, it only produces a fraction of it in comparison with the microbes in our gut. In fact, it is thought that roughly 90% of the body’s total reserves of serotonin are actually produced by microbes in our gut!





Unlike the brain though, the gut’s nervous system works in tandem with many, many microbes that take up residence in our so-called gut microbiome.


Now, whenever someone mentions microbes nowadays, most people’s reaction is to run and grab the sanitiser. But we are actually more accustomed to microbes than you might think. By the age of three, each of our gut microbiomes contain about 100 trillion microbes (just for perspective, that’s this number: 100,000,000,000,000). Within this number, there are an estimated 500 million different species of bacteria, viruses, archaea and fungi that make their homes in our digestive tracts. That might sound slightly off-putting and maybe even a little scary, but our microbiome community is actually filled to the brim with microscopic helpers whose job it is to help us make the most of the food we eat and make the most of our lives.


One crucial role the microbiome plays is in the creation of chemicals called neurotransmitters. These chemicals, which the brain also creates a lot of, are important factors in how our body reacts in response to internal and external stresses. One example neurotransmitter is serotonin which plays a big part in helping us feel upbeat and positive. Although our brain manufactures some of the serotonin in our bodies, it only produces a fraction of it in comparison with the microbes in our gut. In fact, it is thought that roughly 90% of the body’s total reserves of serotonin are actually produced by our microbiome!


A case study: the effect of stress on the mind and the gut


So why is knowing all of this information important when it comes to mental health?


The answer: Because our feelings and emotions can have a major impact on our gut.


Let’s take stress for example. When we are put into stressful situations, our body has a physical reaction to that stress, releasing chemicals called hormones that give us a wake-up call and make sure that we’re alert and ready to deal with whatever threat the body perceives.


During this initial release of hormones, the body signals to the digestive system to pause in order to focus as much energy as possible on escaping the danger. This process leads to a sensation we are all familiar with: butterflies in our stomach. That feeling is actually caused by blood moving away from our stomach to our muscles so that we are more prepared to fight off whatever threat may come our way.

 

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The fight or flight reaction has evolved over hundreds of thousands of years to protect us against threats. But what happens to our gut when we are forced into a state of fight or flight for a longer period of time?


If we don’t allow time for our bodies to rest after physical exertion, or if we don’t find ways to relieve the stress we may experience in our daily lives, it can result in inflammation being created in the gut and spreading throughout the body.


Why this is the cases comes down to that aforementioned effect that stress can have on our digestive system. As hormones like adrenaline and cortisol are released by the brain, processes involved in our digestion are forced to slow down and, because our gut isn’t able to properly rid itself of harmful toxins, our digestive tract can become inflamed.


Inflammation is a common symptom or cause of diseases, and when the body isn’t allowed the time to rest and deal with it, inflammation in the body can cause autoimmune diseases as well as digestive issues such as Irritable Bowel Syndrome (IBS).


The flipside to all of this of course is that, when inflamed, your gut may not be able to produce the neurotransmitters it usually does. Remember serotonin – that chemical mentioned earlier that plays a big role in our happiness? Well if our gut is inflamed, the amount of serotonin it can produce can be severely hampered, effecting our overall mental wellbeing.



It takes guts to take care of your gut!


This might all sound scary, but thankfully, with the right foods, we can do something to protect the intricate relationship between our gut and our brain.


One very important element of our diet which we really should pay more attention to is fibre. Fibre is what microbes live for (literally) so ensuring we get enough of it gives our microbiome the right fuel to get producing those all-important neurotransmitters.


One of the best places to start getting enough fibre is fibrous fruits like apples, bananas, oranges or raspberries. Vegetables and grains like oats are also good sources of fibre, while fermented foods like yoghurt have long been considered allies to our gut due to the presence of live probiotics.


On the point of probiotics, tablet forms do exist, however many experts have doubts about the efficiency of those you buy in supermarkets due to their shelf life. If you do want to invest in some probiotics, it’s best to get professional advice on which ones would best suit your body’s needs.


For some more diet inspiration, check out the table below!


All the foods that can help build a diverse and healthy microbiome. Disclaimer: Although dirt is a rich source of bacteria, we’re not so sure about sprinkling compost on our cereal just yet! Source: Prostate Cancer Foundation



Believe it or not: Psychological therapies can help too!


It’s not just our diet that can help our gut though – psychological therapies can have a positive effect too!


A treatment called gut-directed hypnotherapy has emerged as a non-invasive and highly effective method of treating the symptoms of IBS. Focusing on calming the mind, gut-directed hypnotherapy helps people with IBS learn how to influence and gain control over their gut function, and actually causes a change in how the brain governs their gut activity. If you wanted proof of how your gut is related to your mental health, gut-directed hypnotherapy is definitely it!


Look after your body and mind


Hopefully, after all of that information, you have a new-found appreciation for the importance of the Gut-Brain Axis. So, if your mental health isn’t at its best, give a change of diet a go or maybe even see if you can get some gut-directed hypnotherapy to you’re your friendly neighbourhood microbes do what they’ve been born to do: look after your body and mind!

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