• Sarah Hickson

Gut Health and Mental Wellbeing...Understanding the Connection Part 1

Updated: Aug 12, 2020

The Brain Inside Our Gut and How Stress Harms Our Digestion

My passion for health and wellbeing began in my mid-teens due to my own dealings with anxiety and digestive issues and my growing fascination with the human body. Little did I know back then that the two conditions were intricately linked and influenced by each other and like throwing fuel onto a fire, they were consistently aggravated by the poor dietary choices I made (yes, I used to live off foods that were highly processed and high in sugar). Of course, there were other factors affecting me too such as how I was perceiving my experiences, my internal dialogue (the way I would speak to myself) and habitual thought patterns. Because I was always paid close attention to my inner critic and would believe every word that it spoke to me, my shame about not being "good enough" fed into my anxiety too (if you would like to read more on how perception influences our wellbeing please click here).

The notion of the gut influencing our health is nothing new. Hippocrates, known and respected as the father of modern medicine knew this more than 2,000 years ago, stating that “all disease begins in gut.” However, it is only now with the advances of science that we are now able to scientifically understand the connection, especially in the arena of mental health and psychology. We now know that the gut is more than just a passage way for the digestion of food and the elimination of wastes. We are learning that beneficial strains of microbes living within the digestive tract help our human cells to sustain life from birth right through to old age, yet conversely harmful bugs can play havoc inside the body and be a disaster for our health. We have only recently discovered that unlike any other organ in the body the gut has its own independent nervous system which enables us to move, mix and churn our food through the digestive tract so that nutrients can be absorbed and wastes be eliminated. It also provides us with the sensation of feeling our inner world and can react before the brain in our head does to something that doesn’t feel right. And finally, through its communication to the brain via the vagus nerve by a range of chemical messages including neurochemicals produced by our gut microbes, inflammatory chemicals and toxins, we are discovering that the state of our insides has a huge influence our mental state too. By impacting our thoughts, our emotional patterns and our behaviour, this new understanding is revolutionising the way we approach mental wellbeing.

I have a gut feeling…where does that even come from?

Have you ever used that phrase before? Have you ever made a decision based on how your gut felt about it and you sensed this as your intuition? Or what about experiencing the sensation of “butterflies” in your stomach, that feeling of internal stress or nervousness as you anticipate an upcoming event?

The experience of those “gut feelings," along with the sensations of “fullness” and “bloating” are thanks to a network of mesh-like nervous tissue that innervates our digestive tract called the Enteric Nervous System (ENS).

The Brain of the Gut

The ENS consists of two thin nerve layers that are embedded within the lining of our digestive tube, beginning from our oesophagus and extending all the way through to our rear end (yes, that would be the anus). There are more than 100 million neurons found throughout this nerve network, containing more neurons than either our spinal cord or peripheral nervous system, thus the ENS has respectfully earned itself the reputation of being our "second brain" or the "brain of the gut.". It also utilizes more than 30 different types of neurotransmitters, most of which are identical to the ones found within our brain and spinal cord. In fact, 95% of the body’s serotonin lies within the gut along with 50% of the body’s dopamine, two chemicals that are associated with feelings of happiness, pleasure and motivation.

From swallowing food, “passing motions” through to the sensation of gut feelings (both physical and emotional), with its own senses and reflexes the ENS controls our digestive behaviour independently from the brain, perhaps to relieve the burden so that the one in our head can focus its energy on receiving, interpreting and relaying messages throughout the body as we think and respond to our environment and those around us.

Rhythmic muscle contractions stimulated by these nerves moves food through the digestive tract, mixing and churning it with our digestive juices and enzymes so that our food can be broken down into smaller molecules to be absorbed and distributed to hungry cells throughout the body.

A Stressed Tense Body and its Impact on Digestion

While the ENS can take care of our digestion independently, its activity is managed by branches of nerves of the autonomic nervous system, an involuntary arm of our nervous system that is responsible for controlling our breathing, blood flow and digestion. Consisting of two divisions termed the "fight or flight" sympathetic nervous system (SNS) and our the "rest and digest" parasympathetic nervous system (PNS), these systems regulate the speed of food moving through the digestive tract, the production of protective mucous on the intestinal lining and the release of stomach acid in response to ingested food. The vagus nerve of the PNS forms neuronal connections with nerves of our ENS. When our body is relaxed the vagus nerve increases the activity of our ENS neurons and in turn stimulates the release of our digestive juices and digestive motion is put into place. In contrast, during those times when we are stressed, anxious or angry our whole body tenses up and like a switch the “fight or flight” division of our nervous system kicks in, shutting off or limiting digestion in favour of preparing our body to deal with the perceived threat (which in this day and age is simply just being stuck in traffic when you’re running late for a meeting or if you're anything like me, a complete failure at multi-tasking but continue to do it anyway). On the other hand however, for some people the motions can be sped up, especially in the case of irritable bowel syndrome. For these people the feelings of high stress and anxiety can cause hyperactivity, fast passage of food and spasming of the gut which can then send them racing off to the bathroom in anticipation of or following a stressful event. If this reaction is occurring on a regular basis it can limit the amount of beneficial nutrients that get absorbed and can result in multiple nutritional deficiencies. Often in these cases there other multiple other issues at play such as intestinal microbial overgrowth (which cause sensitivities to lactose and FODMAPS) miscommunication between the gut and brain, high cortisol levels and visceral hypersensitivity (a heightened sensitivity to pain).

Time to Tune in, How Frequently is Your body is Switched onto Fight or Flight Mode?

Unfortunately, the norm for modern living and western society is to pile our plates full of things to do and to eat in a hurry. Rarely (or infrequently) do we allow ourselves a chance to stop and take a moment to switch off and relax. Feeling tense and stressed can click us out of rest and digest mode meaning that our digestion all too often isn't operating at its full capacity. This can cause or contribute to the experience of gut problems such bloating, painful wind, diarrhoea or constipation, reflux and so on (do any of these symptoms sound familiar to you?).

The Gut Brain Link

Did you know that our brain and gut are constantly speaking to each other, with our gut dominating the conversation? This is made possible via the vagus nerve. In addition to its important role of regulating digestion, the vagus nerve also acts as a super highway by linking the gut to the brain, transporting a range of chemicals and hormones to alert the big brain about when we're feeling hungry, if we've ingested an infectious bug or if we are under stress. When our gut is inflamed and infected by conditions such as coeliac's disease, irritable bowel disease, infection caused by harmful microbes or even persistent feelings of overwhelming stress (which can throw the whole system out of balance), inflammatory chemicals and bacterial toxins are also transmitted to the brain from our gut. Research studies have found that these chemicals have the power to impact our mental wellbeing in a negative way by potentially souring our mood, creating feelings of anxiety and altering the way we perceive the world and in turn, our emotional response towards it.

So to Conclude, What Does Your Gut Tell You About All this Information?

If you tune in and listen, I’m sure that it would tell that it’s time to pay it some attention.

If you’re trying to figure out why moodiness, anxiety and low mood have been problematic for you yet these symptoms are also coinciding with symptoms such as frequent bloating, wind, constipation or diarrhea (or both) and reflux then I would have an inkling that there was a link between the two and this would need to be addressed. Likewise, if your diet was deficient in the very nutrients that our brain craves to create the chemicals that help us to feel good, motivated and calm then this would need to be addressed too (more on this in my upcoming blog posts). Optimal digestion starts with learning how to activate our parasympathetic nervous system, and this can be done through effective stress management and mindfulness. To help your body get into rest and digest mode, here's a few mindful eating techniques to get you started:

A Guide to Mindful Eating

Breathe Deeply

To help activate the PNS breathe in slowly through your nose, breathing in deeply from your abdomen, allowing your diaphragm and lungs to fill up with air. Hold for 1-2 seconds and then allow your breath to slowly release through your mouth. Repeat 2-3 times.

Set a Timer

Set a time for 20 minutes and take that time to eat your meal

Engage your Senses

Before you begin eating take your time to notice the aroma of your food and how it looks. When you take your first bite, notice the texture of your food, how it feels and how it tastes.

Eat Silently for 5 minutes

Think about what it took to prepare your meal, what it took to produce the ingredients from the farm, to the grocers to the cook.

Take Small Bites and Take Your Time to Chew Your Food Well

Doing this relaxes the digestive system and promotes the release of digestive enzymes to break down your food. It also tunes you into the appetite signals that tell you when you're satisfied

Avoid Drinking Fluids 20 min Before and After Eating

If you must, only drink small sips of water during eating. Large amounts of consumed at meal time dilutes your digestive juices and enzymes, reducing quality digestion.

Before You Go to Grab Some Food, Take a Breath and Ask Yourself, Am I Really Hungry?

Perhaps you're eating out of boredom or stress. If this is the case, go for a brisk walk or read something instead.


Carabotti, M., Scirocco, A., Maselli, M.A., Severi, C., 2015, The gut-brain axis: Interactions between centric microbiota, central and enteric nervous systems, Annals of Gastroenterology, Vol 28 (2), p.203-209

Fadgyas-Stanculete, M., Buga, A.M., Popa-Wagner, A., Dumitrascu, D.L., 2014, The relationship between irritable bowel syndrome and psychiatric disorders: from molecule changes to clinical manifestations, Journal of Molecular Psychiatry, Vol 2 (4)

Houser, M.C., Tansey, M.G, 2017, The gut brain axis: Is intestinal inflammation a silent driver of Parkinson's disease pathogenesis? Nature Publishing Group, Vol 3, Viewed on 1/9/17 https://pid.emory.edu/ark:/25593/s3hhm Rodriguez, J.M., Murphy, K., Stanton, C., Ross., P.R., Kober, O., Juge, N., Avershina, E., Rudi, K., Narbad, A., Jenmalmo, M.C., Marchesi, J.R., Collado, M.C., 2015, The composition of the gut microbiota throughout life, with an emphasis on early life, Microbial Ecology in Health and Disease, Vol 26 (10), accessed from Pub Med Central on 29/08/17 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4315782/#__notesidm140656885169712title

Sonnenburg, J., Sonnenburg, E., 2015, Gut Feelings - the "second brain" in our gastrointestinal system [excerpt], The Scientific American, Viewed on 1/9/17 https://www.scientificamerican.com/article/gut-feelings-the-second-brain-in-our-gastrointestinal-systems-excerpt/

Tortora, .G., Derrickson, B., 2014, Principles of Anatomy and Physiology 14th Ed, Wiley, USA

55 views0 comments