The gut and brain connection

There is a definite relationship between our gut and our brain!

You may not be aware but we actually have two nervous systems the central nervous system, composed of your brain and spinal cord and the enteric nervous system, which is the intrinsic nervous system of your gastrointestinal tract. The stomach and intestines actually contain more nerve cells than the entire spinal cord. Consider this: 95 percent of the body’s serotonin — a hormone that helps control mood — is found in the digestive system, not the brain.

Both the central and enteric NS are created from identical tissue during fetal development—one part turns into your central nervous system while the other develops into your enteric nervous system. This ensures a permanent link between the gut and the brain. The vagus nerve connects the two systems which is the tenth cranial nerve that runs from your brain stem to your abdomen. It is now well established that the vagus nerve is the primary route your gut bacteria use to transmit information to your brain.​

In the intestinal mucosa there are blood vessels that are influenced by the autonomic nervous system (which regulates the functions of our internal organs). The intestinal mucosa also is infiltrated by the myenteric plexus which is a network of nerve fibres and neuron cell bodies that are in turn influenced by the brain. So, basically the gut is one big nervous tissue.

Our gut bacteria also outnumber human cells in the body by 10 to 1. We have a hundred trillion bacteria in our gut and if you look at it that way you could say that we’re more bacterial than we are human. When you consider it that way it’s not that surprising that the composition of the gut flora can have so many effects on everything from our metabolism to our behaviour. While many think of their brain as the organ in charge, your gut actually sends far more information to your brain than your brain sends to your gut…​

To put this into more concrete terms, you’ve probably experienced the visceral sensation of butterflies in your stomach when you’re nervous – like this talk I am giving right now, or had an upset stomach when you were very angry or stressed. The flip side is also true, in that problems in your gut can directly impact your mental health, leading to issues like anxiety and depression.​

Because in a very real sense you have two brains, one inside your skull and one in your gut, and each needs its own vital nourishment. This is highlighted by the fact that the ENS can actually function independently from the CNS. All of the key neurotransmitters found in the brain including serotonin, enkephalin, histamine, substance P, noradrenalin and substance P can be found in the gut as well. When the gut isn’t functioning optimal absorption and assimilation of nutrients is compromised. This impact the availability of nutrients and can affect our entire body including our mental health.​

The gut brain-axis is very sensitive and there are many things that can disturb it.

One very common one that most of us experiences is stress.

In times of stress, our bodies are designed to focus on the things that can help us stay alive. When our ancestors had to fight off hyenas or run away from cave bears, they didn’t want to waste any energy on less important things like proper digestion.

When the brain feels severely stressed, it unleashes a cascade of hormones that can put the whole digestive system in an uproar. The hormones have different and sometimes contradictory jobs. For example, the hormone CRH (short for corticotropin-releasing hormone) is one of the body’s main alarm bells. In stressful situations, the brain pumps out CRH to tell the adrenal gland to start making steroids and adrenaline, chemicals that can give you the strength and energy to run or fight your way out of trouble.

CRH also turns off appetite, which explains why some people can’t eat anything when they’re stressed. At the same time, the steroids triggered by CRH can make a person hungry, which is why some people fight stress with ice cream or chocolate. When CRH turns off appetite that means that there is a decrease in digestive capacity – as a result we experience less HCL, less digestive enzymes, decreased digestive capacity and therefore less availability of nutrients. Our nutrition basically goes through us without getting absorbed.

Sugar and carbs and fat can mitigate the effects of stress via increasing opiates and dopamine and other neurotransmitters like serotonin that make us feel good, feel like life’s okay and everything’s gonna be fine. But if you do this regularly during times of stress you can cause adaptations in those pathways that can lead to overeating. Other studies have shown that food reward and sensitivity is decreased during stress, which leads to overeating. In other words when you’re really stressed out you don’t actually enjoy the food that you’re eating as much as you do when you’re not. And then you keep eating because you’re not getting that food reward that you’re expecting.

Anxiety, stress and the gut and the brain, they’re all part of the same axis, they always go together.

Every stressful event that we experience in life increases the plasticity of stress pathways in the brain, which means it makes the brain essentially more efficient at running stress pathways. And there’s a saying in functional medicine, fire in the gut, fire in the brain. Which sums it up pretty well.

Consider this– antidepressant drugs such as SSRI’s cause gut- associated side effects because they increase serotonin levels in the brain and in the gut – which increase gut motility and nausea. This further demonstrates that out emotions can have a physiological impact on the functioning of our gut

One of the coolest things about Chinese medicine (and Chinese philosophy in general) is that they don’t really tend to see things in linear fashion. They see things in a cyclical way. And the way they look at the body, they would never say ‘this causes that’, like from A to B. It’s always ‘this and that’. For example, they’ve always recognized that the emotions, psychology, and physiology are one in the same.

So, how do we ensure that our gut stays healthy?

A few simple things like; lemon in water before meals to stimulate HCL and pancreatic enzymes. 

In the warmer seasons you incorporate Papaya as it contains papain – to help digest food

Probiotic foods – Fermented vegetables like kimchee and sauerkraut fermented beverages like kombucha. Also kefir or coconut kefir. There is a great book called Wild Fermentation by Sandor Katz that has like, every possible fermented food you can imagine and how to make it.

Most importantly; stress minimisation – yoga, tichi, walking, meditation – making time for yourself! 

Love Rhiannon & Rachael, HOM xx 

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