The gastrointestinal tract is one of the largest organs in the human body as it is forty times larger than the area of the skin and has a total dimension of 8 metres. It also has 100 trillion bacteria that influence the activity of our large intestine. Not only this but, as incredible as it seems, it helps produce more than 20 types of hormones. Moreover, scientists have determined that most of our immune cells are trained in the gut. Apart from this, it has the ability to clean itself after digestion. Fascinating, isn’t it? But this proposes one question, how could this possibly happen?
First of all, it is important to mention that there is a clear relationship between the brain and the gastrointestinal tract via the gut-brain axis. This allows the GI tract to send information to the central nervous system (which comprises the brain) via a “communication network” formed by the Enteric Nervous System (ENS) found within the walls of the GI tract. This works by notifying the brain, through nerve impulses, of key information from the gut. This subsequently impacts how we respond and how we feel. After I came across this fascinating concept, I went to look for scientific papers for extra information and most of them explained a direct link between our gut and mental health. This provides evidence as to why people suffering with gastrointestinal disorders such as Ulcerative Colitis and Irritable bowel syndrome (IBS) have an increased incidence of depression and anxiety.
I didn’t know this topic was even more interesting until after I chose my BIOL243 (Medical Microbiology) essay topic on how an imbalance of our commensal flora (dysbiosis) can lead to depression and anxiety. In it, I spent roughly around 2 weeks reading scientific papers and gathering information about the consequences the disruption of the microbiota has on our mental health. To my surprise, I learnt something I didn’t know before: how a decrease in the number of commensal bacteria leads to the appearance of pathogenic bacteria in our system, which in turn makes us highly susceptible to disease. This is linked to the statement I made in the first paragraph, about how our gut is responsible for the homeostasis and differentiation of our immune cells. This process helps control the type of pathogenic bacteria that enter our gut as they could severely harm and disrupt the normal commensal flora. Therefore, when dysbiosis happens, the microbiota gets disrupted so we are more prone to infection and also, more likely to develop mental health issues.
It is in fact mind-blowing. It’s incredible how our gastrointestinal tract, which normally does not seem so important to us, is necessary for the correct development and function of the human body. Basically, without it we would not be able to thrive and be physically healthy.
Written by: Lenka Gallego