The sci-fi Second Brain

So it turns out we have a ‘second brain’. Yes, that’s right, a second brain. And no ladies, it’s not where you think most men’s would be.


We do all have what is being termed as a ‘second brain’, and for all of us it is in the same exact spot. It is also referred to as our enteric nervous system or ENS.

It is a completely different nervous system to the Central Nervous system that is attached to the brain in our skulls, and is made up of roughly 500 million neurons or nerve cells, which is roughly 400 million more than that of a rats normal brain.

It stretches an estimated 9 metres long from our mouths to our anus. It thinks and feels and is responsible for releasing hormones and neurotransmitters just like the brain in our skull does. It can even sense danger, record experiences; respond to emotions, and environmental threats before our ‘head brain’ can.

And in a slightly sci-fi way, it can learn too. (Young)


It is where? In our gut, woven throughout the many layers of the wall of the entire digestive tract: Starting at our esophagus, travelling along with our stomach, small intestine and finishing off where the colon exits our butt. It is considered to be a single entity of its own. And has long been known to have control over digestion. But what has been a huge surprise is the significant effects this ‘gut brain axis’/’second brain’ or ‘Enteric nervous system’ has over ones thought, behavior and emotional health. And the roles that even our gut bacteria and food choices have on influencing these too. (Young)


Even though the discovery of our highly intelligent, thinking, feeling gut brain is relatively new science, it makes all those old references to this exact process rather curious, such as- ‘trust your gut feeling’, ‘listen to your gut instincts’, go with your gut’, ‘I had a bad feeling in the pit of my stomach about the whole thing’.


The story of our second brain begins many years ago in a primitive world. It was, in seems, the original nervous system and thinking centre for most vertebrates more than 500 million years ago. And as vertebrates evolved, becoming more complex, a new brain was born- our ‘head brain’. So really our second brain should be called our first, and vice versus, but what can you do? (Young NS)

The two brains are connected by one cable: the vagus nerve.

The gut brain is so very sophisticated that even severing this one connection between the two brains leads to no change in the functioning of most of its physiological tasks.


So let’s have a look at what makes up our second brain:


The enteric nervous system (ENS) is a part of the nervous system and is somewhat automated, meaning we don’t need to think about it in order for it to work- like you do to move your arm up and down etc. Being a nervous system, it is made up of a network of nerves or neurons as they are also called. And as we mentioned earlier, there are hundreds of millions of neurons within this gut brain. A neuron is basically a type of cell that processes, carries and transmits information via electrical signals or chemical messengers to other parts of the body. The information these particular enteric neurons commonly carry is that which affects the movement of organs and secretion of glands. (Costa)


Or; and this is where some of the elusive mystery has laid, the ENS can work in conjunction with the brain where information is sent to the brain from the gut relating to well-being and the safety of the environment which may not ever come into conscious thought, but you will still respond to it adequately without knowing you just did. (Young)


The gut brain is the main area responsible for our happiness and sadness. Our gut is also the major producer and releaser of the neurotransmitters serotonin- commonly known as the ‘happy hormone’, and it additionally contains dopamine, glutamate, norepinephrine, and even nitric oxide. (King)


What else is in our gut? Bacteria. Cell for cell, humans are mostly bacteria 10 to 1, with most of them residing in our gut. The ‘gut brain’ has in fact evolved over time in order to protect and use this bacterial ecosystem to our advantage, both physically and mentally. (Carpenter)

These bacteria, and the specific types of bacteria control the gut, how it functions, helping us to digest foods and affecting our metabolism; they also manufacture vitamins from the foods we have eaten. And your gut bacteria literally designs and programs your entire immune system, they build and strengthen the gut wall, influence emotional behavior, the perception of pain, and even stress responses.


Think of it this way, you basically have a Country of individuals residing in your abdomen. There are multitudes of varying nationalities there, and differing religious beliefs. Wars can break out for supremacy between the different camps or groups. Some are good and some are bad. It’s a bit like the complicated conflict in the Middle East: there’s lots of fighting going on, many wars between many different groups and Nations, who’s good, who’s bad? They all think they are good, but the point is that whichever group is in dominant power, then determines how that country is run thereafter. In the gut the same battle is going on. The battle is between what we loosely term as ‘good gut bacteria’ and ‘bad bacteria’, which are called so because they can cause disease and illness when they thrive. In the gut, whom ever wins the war ends up running the entire human they are residing in, from how they digest food, to how they think and feel.


Gut bacteria manufacture hundreds of neurochemicals that are used by our ‘head brain’ to regulate basic mental processes, such as memory, learning and mood. It was found that higher levels of good bacteria in the gut affected brain chemistry in such a way that the host felt and acted more boldly. Whilst the ‘insipid badness’ of bad bacteria can make the host highly anxious.

And even more staggering, our gut produces hormones and contains around 40 neurotransmitters that are identical to those made by our brain. There is as much dopamine in our gut as in our head and it is our gut bacteria, which produce around 95% of the body’s supply of serotonin- the ‘happy hormone’! Remarkable really. (Carpenter)


So what exactly are these neurotransmitters doing in our gut?

In the brain, dopamine is responsible for the pleasure, reward system. But in our gut, it helps with movement of the colon too. And Serotonin is the ‘feel good’ hormone, responsible for making us feel more uplifted. Some of its other jobs are in regulating cell maintenance in the liver and lungs, heart and bones.



Could this all mean that we could treat psychiatric illnesses with good gut bacteria or probiotics? Yes, very possibly.

Let’s look at some gut disorders that interestingly often involve a psychological component. IBS and anxiety often travel together, as does depression and other chronic GI disorders such as celiac disease. (Carpenter)

And not only that, it works in the other direction too. In 2004 in the Journal of Pediatric Gastroenterology and Nutrition, it describes how our brain can alter gut bacteria balance where even mild stress has a powerful manipulation on gut bacteria, tipping it towards the ‘baddies’, and thus making us more susceptible to illness and infection. While a study done in 2008 by Swinburne University of Technology in Australia found that during exam week, uni students had less lactobacilli bacteria present in their stools compared with the ‘unstressed’ weeks. (Carpenter)


How does this all happen?

It seems that soon after birth, the particular microbes present in the gut actually help program aspects of brain development in relation to stress response. Some studies state that the bacteria communicate with the immune system; using their cells and the chemicals they produce to communicate with the brain like Chinese whispers. Other studies suggest that the bacteria use the vagus nerve like a telephone line, to talk with the brain directly. Sounds very Artificial intelligence, very Steven Spielberg, but no, this is just the universe within your own body.


Do the foods we eat have an impact on emotions too?

Eating food is vital to our survival, which is why there is a ‘reward centered’ response when we eat. But what happens if we feel a different emotion, like sadness for instance? It was found that when we feel sad, we want to eat more. This was found to be stemming from our ‘reward centre’ and gut brain chatting and then setting up different parameters to make us happier, faster- and food was the drug of choice in this instance. It works to a degree, but if you are chronically depressed and being told to eat all day long by your ‘over-mothering’ reward centre, you may not be too happy with the long term results, setting up more depression over the inevitable weight gain, and then more signals to keep eating to ease this new depression. (Van Oudenhove)


In a study carried out in 2011, healthy volunteers were induced into sadness through listening to heart felt music, then given fatty acids. This study was looking for a physical relationship between what was in ingested, and how that impacted emotions via the vagus nerve communicating with the medulla, hypothalamus and cerebellum in the brain, form the gut brain. And it worked. Fatty acids were found to make the volunteers less sad. (Van Oudenhove) The use of, particularly omega 3 fatty acids, in cases of depression and anxiety had been around for many years, but here was evidence.


Now, take for example Autism and autism spectrum disorders. These are generally characterized by difficulties in three main areas: communication; where there is a delay in learning language and in some cases, the person affected does not speak at all. Socialization; where they find it extremely difficult to read non-verbal cues from others or form friendships. And restrictive and repetitive behaviors and compulsions such as lining up objects in a particular way, or staring intently at moving objects.


Imagine you were the parent of this child who couldn’t talk or communicate with you; how when you held them there was no emotional attachment or ‘bond’ formed, and they spent their day either screaming or repetitively flapping their hands. What would you do? Anything and everything. You would pay any amount of money for the newest form of counseling, drugs and toxic metal chelation therapies. But what if it all began with the gut? And here lies a mystery: autistic children’s gut and intestinal mucosa are all noticeably damaged, but by what?


It seems it could be particular foods causing this mucosal damage, which, when eaten, triggers inflammation and the release of specific hormones and chemicals, which are manipulating brain chemistry and behavior of these poor children. Sounds crazy right?

Yet, in a review article published by The American Academy of Clinical Psychiatrists the simple removal of dairy casein and gluten from the diets of autistic spectrum children, and schizophrenic patients, improved all their symptoms, including behavioral problems significantly. (Reichelt) Strange coincidence?

And there is much anecdotal evidence of this too, with mothers saying such things as- ‘their 6 year old child spoke words for the first time in their entire lives only weeks after removing these foods from their regular diet’.

It should be noted that scientific research is suggesting that to see the full potential of improvement, a year or more needs to be maintained of gluten and casein free. And we aren’t even covering food additives, preservatives, colours and pesticides here, and the effects they have on health and emotions.


Moving away from mood disorders, just eating in general is ridiculously dangerous actually. There is so much that can potentially go wrong when a typical human spends it entire day constantly inviting unknown and possibly pathogenic ingredients, such as bacteria, chemicals, and food allergens, into the very interior of itself. Another reason why there are so many neurons here.

So what does the second brain and neurotransmitters do when a gastrointestinal infection or tummy bug does get in? Signals an all out evacuation, and usually of a violent kind in the form of diarrhea or vomiting or the lovely combination of both, when it just isn’t sure which one would be best. (Young)

And if a disease-causing bug does survive the defenses of the gut and sets up residence there, it was found that within hours of infection of a pathogen in the tummy, rapid changes occurred in the brain. The brain was affected via the vagus nerve again, increasing certain neurotransmitters and hormones, which affected then behavior. In the instance of Helicobacter pylori infection- the bacteria often associated with the development of gastric ulcers, it was found that plasma levels of the hormones responsible for regulating appetite: leptin, ghrelin and CCK were all altered, and the subjects were driven to eat more frequently, while their bowels emptied less. Not a good combination when you think about it, particularly for weight loss. (Premysl)


Luckily some health professionals and even personal trainers, like your very own highly intelligent and well read PT- Cato Rutherford from George St fitness first gym, knows all about the gut brain axis, and treats his clients using this knowledge. Cato is pretty switched on to recognize a client who are in a state of inflammation due to their out of whack gut bacteria, and says that if he can train their body whilst also educating them on how to eat to help their gut-brain, those clients tend to do very well.

“I see a lot of stress related gut problems, and gut related brain problems. Gut bacteria is so essential to weight loss and training outcomes, not to mention over-all health; pro, and pre-biotics are like the “Penicillin” of the 21st century.” Cato says.


He also encourages simple things like switching to organic foods, which are naturally higher in vitamins, minerals and enzymes. Removing inflammatory foods that could be affecting their gut bacteria, hormones and weight. And even teaching them simple relaxation techniques- again to lower stress, which can physiologically lower the inflammation response, and helps with weight loss. “If you feel great and are exercising well, life’s good” Cato says.


Wow, what a journey through a biochemically complex universe. Who knew our body, and particularly our gut, was so remarkably intelligent as to think, learn, and remember independently of itself and with the brain in our skulls? That the residence of our gut bacteria world actually communicate with our brain as well, to influence its behavior, thoughts and feelings and it could all be turned around by simply eating differently, stressing less or by which balance of good or bad is ruling the kingdom at the time.

That it is this ‘second brain’ that is partly, if not entirely responsible for illnesses such as depression, Autism and schizophrenia?

While it is overwhelmingly complicated, this scientifically shows us that our whole being can basically be influenced by what we eat and the bacteria within us; food for thought…



Published by honnutrition

Qualified Nutritionist, Health Writer, Nutritional Journalist. Nerdy with a touch of class.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: