The communication path between the gastrointestinal tract (the gut) and the central nervous system (the brain) is known as the gut-brain axis. The cross talk between these two organs is bidirectional in nature and involves a complex network of neuronal, hormonal, and immune signalling pathways.
Imagine you are about to give an important presentation. As the time approaches, you start feeling those familiar “butterflies in your stomach.” This sensation is a classic manifestation of the gut-brain axis.
In response to the anticipation and stress of the presentation, signals travel from your brain through the autonomic nervous system to your gut. This communication prompts changes in the gut’s functioning. The gut becomes more sensitive, and there is an increase in blood flow and the release of certain hormones.
Conversely, the gut sends signals back to the brain via the vagus nerve, which is one of the longest and most complex set of nerves in the body informing it about the gut’s state and influencing the brain’s response to stress. These signals can affect your mood, anxiety levels, and even cognitive function.
The gut-brain axis has been part of large studies to understand how both organs can affect important psychological processes, including digestion, metabolism, immune function, and even behaviour and mood regulation. Disruptions in the gut-brain axis have been implicated in a range of disorders, such as irritable bowel syndrome, inflammatory bowel disease, obesity, and even mental health conditions like depression and anxiety.
Many studies now say that the gut may be communicating with the brain through the gut microbiome, which is the term given to the collection of microorganisms found in the gut.
“The signals arising from your gut come from the gut microbiome. The gut microbiome sends signals to your brain via the vagus nerve, which [facilitates] the release of the stress hormone cortisol, and that is what causes a physical and emotional reaction to the stress,” says Dr Pujah Kundaar, lead nutritionist at The Good Bug, a probiotic company.
The gut microbiota interacts with the gut-brain axis through other communication channels as well like producing neurotransmitters, such as serotonin, dopamine, and gamma-aminobutyric acid (GABA) that play essential roles in regulating mood, emotions, and cognitive function.
With the brain and gut so intertwined, it makes sense that researchers are now looking for ways to treat gut disorders by using this gut-brain axis. For example, scientists are now looking to treat brain disorders such as Parkinson’s disorder by looking at the gut-brain axis for answers.
