Updated: Sep 14
You know that butterflies-in-your-stomach feeling you get before giving a big presentation? Or when you’re waiting to hear some important news? You can thank your second brain for that.
More and more research is supporting the idea that our gut and brain are closely connected, both physically and chemically. So much so, that our stomachs are referred to as our “second brain” by some scientists.
We’re beginning to find that this gut-brain axis is likely a two-way street, as well. Meaning, our mental state can affect our gut – that nervous “butterfly” feeling – but our gut may affect our mental state. So, having a digestive disorder, like Irritable Bowel Syndrome (IBS), may be a factor in someone’s mental health.
The Vagus Nerve
One reason why this relationship is thought to be so integrated is the vagus nerve. This nerve is what physically connects the gut and brain and has a number of different functions.
One of the bodily systems it affects is our parasympathetic system. This system is responsible for our digestive tracts, respiration, and heart rate. If you’ve ever done heart rate variability (HRV) training with us at Neuropeak Pro, it’s your vagus nerve that’s helped regulate your heart rate and breath. It also makes sense that it would play a role in both mental and digestive health.
Interestingly, studies have suggested that stress may affect the way this nerve sends signals. While the research is in early stages, this response could contribute to gastrointestinal issues. Another study found a link between people with IBS or Crohn’s disease and a reduced function of the vagus nerve.
Additionally, some research has suggested that people with gastrointestinal disorders may be more sensitive to pain than people without GI disorders. This could be due to the brain being more responsive to pain signals coming from the gut.
The gut-brain connection exists on a chemical level, as well. Neurotransmitters are chemical substances that transmit signals across synapses. However, neurotransmitters aren’t just produced in the brain. Many neurotransmitters, like serotonin, are also produced by the microbes living in our gut.
An important neurotransmitter produced in the brain and gut is gamma-aminobutyric acid (GABA), which plays a role in how we regulate fear and anxiety. Some studies have suggested that certain probiotics may affect how GABA is produced in the gut and could even reduce anxiety symptoms.
These findings may even help explain why there’s a disproportionate amount of people grappling with a mood disorder, like anxiety or depression, along with digestive issues.
As we continue to learn more about the engagement between the gut and brain, doctors are beginning to treat some conditions in new ways. A Crohn’s patient may now be given antidepressants. An IBS sufferer may be prescribed talk therapy.
This isn’t to say that people with digestive issues are all also dealing with a mental health condition (although, as we now know, many are). Instead, there may be a previously overlooked disturbance in the way the gut and the brain are interacting. Treating one may just help treat the other.
Harvard Health Publishing. “The Gut-Brain Connection.” Harvard Health, www.health.harvard.edu/diseases-and-conditions/the-gut-brain-connection.
Robertson, Ruairi. (2018, June 27). “The Gut-Brain Connection: How it Works and The Role of Nutrition.” Retrieved from https://www.healthline.com/nutrition/gut-brain-connection
“The Brain-Gut Connection.” Johns Hopkins Medicine Health Library, www.hopkinsmedicine.org/health/wellness-and-prevention/the-brain-gut-connection.