Gut Brain Axis - Why Our Guts Matter
What do you really know about your Guts aka your Gastrointestinal Tract? You know they contain your small and large intestine, your colon, and your stomach right? Yes, but only partially correct. Let’s take a quick look at what your ‘Guts’ really are and some of the key functions they perform so that the rest of this article makes way more sense!
(1)
Quick summary for you:
Your digestive tract starts with your mouth, the saliva in your mouth begins to break down food before it ever hits your stomach. In truth that process involves a lot of complex reactions through the bodies use of enzymes.
In the stomach food gets mixed up and broken down even further into chyme which contains stomach acid and partially digested food.
Next the pyloric sphincter opens and allows the chyme to pass into the small intestine where the majority of food is digested and absorbed back into the bloodstream (2 notable exceptions are Iron which is absorbed in the Duodenum and vitamin B12 which is absorbed in the Ileum).
The remaining undigested food, primarily fibre and any other waste products then pass into the large intestine along with water. After a long journey up the ascending colon, across the transverse colon and down the descending colon most of the water has been lost from the chyme and muscle contraction in the intestinal walls help to move this matter (now called a stool) to the rectum where it gets stored before being released via the anus as a poop...or any number of affectionate and disturbing terms we’ve created for this lovely little act our body does to keep us healthy.
Simple right...nope not even a little! Your digestive system is one of the most complex systems in your whole body and what’s more is how it affects another primary organ, one that pretty much runs the shows (or so we think) our brain! How you are wondering, does my gut connect to my brain? Well let's look at it in the most simplified way I can deliver it for you.
Let’s think about it for a minute...you are hungry and smell something delicious in the air. What happens next? You start to salivate a little, you didn’t even think about it but it just happens. This is because signals from your brain are being sent to your nervous system all the time, and in this case it has increased the naturally occurring saliva because the brain is now anticipating food. This thought of food also kicks off gastric juices in your stomach in preparation for food, along with muscle contractions in the stomach and the release of certain hormones.
According to research what is essentially happening is communication between the central and enteric nervous system (enteric meaning the part of the nervous system that governs the gastrointestinal tract), this then links emotional and cognitive centers of the brain with peripheral intestinal functions (2). These functions can range in effects, but as of 2017 researchers have been looking at the connections between our gut microbiota and associated links to Alzheimer's, MS, and Parkinson’s.
Our gut microorganisms can affect metabolic functions via the breakdown of polysaccharides (1) in foods, immune function via GALT (2) and the prevention of pathogen colonization (2). The thought is that when the relationship between the host (you or I) and our microorganism is out of balance it leads to the pathogenesis (3) or progression of a disease. Age, diet, infection and disease are also big factors in how our gut microbiota performs and can vary from country to community based on diet. In animal studies substantial disruption to the microbiota resulted in visceral pain and stress-related disorders, with IBS (irritable bowel syndrome) being the most notable (3).
Ok, if I haven’t lost you stay with me, the point is coming. The real reason why what we put into our delicate guts matters so much is that it is the center of the body and what food you put into your body determines how well your body is going to work. If you give a truck diesel when it’s meant to have gas/petrol you will see things go wrong really quick and eventually that truck will just stop running, same idea with the body. This is primarily because our gut is connected to what is called the Vagus Nerve (4) which is a direct link to our brains via nervous system components.
When the microbiota gut-brain axis is disturbed the most common disorders that arise are the likes of depression, anxiety, IBS, and IBD (2), along with some more serious ones mentioned earlier. Now, maybe you can relate to the depression, anxiety or digestive issues after you have eaten poorly for a few days, drank too much or neglected your physical health in any way. This is because bacteria in the gut, when not kept properly balanced and happy, can stimulate parts of the nervous system that are associated with the issues I just mentioned.
The risk of imbalance in gut microbiota increases with compromised immunity as well, which is again often very closely related to what nutrients we are providing our bodies with. Age can also play a role in decreased immune function and so if you want to be dancing into your 80’s or 90’s start loving your guts NOW!!
Some simple tips to feed your guts better - Think of your microbiome (gut) as a garden, the better soil and nutrients the better a product it produces.
Fermented Foods are full of Probiotics, the good or friendly strains of live microorganisms that help to keep our digestive tract healthy and prevent some illnesses. Samples: Sauerkraut, Kimchi, Kombucha, Yakult, Sourdough bread, Yogurt (the plainer the better or look for one that contains probiotics strains), Kefir, Tempeh, Buttermilk, Cottage Cheese, Mozzarella, and Pickles.
Maybe you have never heard of some of them or really dislike others (I’m not a fan of sauerkraut personally) but you don’t have to eat them all, and definitely not every day of your life. Just trying to incorporate 1 a day or even 4 a week into your diet can help alongside an average healthy diet. Eating few probiotic foods while you chow down on takeaway or sugary drinks will not help you, don’t be fooled.
I’ll have more on feeding your gut bacteria in another blog but in general reach for veggies, fruit, whole grains, fatty fish, lean meat, a bit of dairy, and lots of water, don’t fear dark chocolate or coffee either as both are better for you than you may think!
*Disclaimer...our guts, microbiome, and brains are very complex this is just a simple rundown on some key aspects*
Definitions
Polysaccharides (1) - Type of Carbohydrate (starch, cellulose, glycogen) that is made up of a number of sugar molecules bound together.
GALT (2) - Gut Associated Lymphoid Tissue is a component of MALT (mucosa associated lymphoid tissue) that works within the immune system to protect the body from pathogens especially found in the gut.
Pathogenesis (3) - The manner of development of a disease.
Vagus Nerve (4) - Is a cranial nerve connecting the brain to the body allowing for information signals to be sent.
References
(Henderson R. 2019) ‘The Digestive System’ Published online by Patient, 2019. Available at: https://patient.info/news-and-features/the-digestive-system
(Xigun, Z. et al 2017) ‘Microbiota-gut-brain axis and the central nervous system’ Published online in the Oncotarget Open Access Impact Journal, 2017. Available at: www.oncotarget.com/index.php?journal=oncotarget&page=article&op=view&path[]=17754&path[]=56860
(O’Mahony et al 2014) ‘Disturbance of the gut microbiota in early-life selectively affects visceral pain in adulthood without impacting cognitive or anxiety-related behaviors in male rates’ Published online in Neuroscience 2014, 277:885-901. Available at: https://www.ncbi.nlm.nih.gov/pubmed/25088912/