The Gut-Brain Axis
Naturopath & sports nutritionist Sarah Fehlberg discusses how your brain and your gut are talking to each other.
There is truth in the sayings such as “Oh I feel sick to my stomach with worry” and “I have butterflies in my stomach”.
The science is now very clear – our worries alter our gut function and, our gut function changes our mood.
If you’re a client of mine, you may have heard me talk to you about the difference between The Sympathetic nervous vs Parasympathetic nervous system.
The Sympathetic nervous system
This is our “fight or flight” – this is where hormones get switched on to deal with certain stressors.
In ancestral times it may be running from a bear. In modern times the bear looks like work stress or getting stuck in traffic and the school drop off. Our bodies also see over-exercising, excess caffeine and not eating enough food as stressors, which keep our systems in “fight or flight”.
Our Sympathetic nervous system is a protective part of our stress response, but we don’t need to stay in it all the time.
The Parasympathetic nervous system
Our bodies need to “rest and digest” and the Parasympathetic nervous system is how we get there. This is when the nervous system is calm and balanced, and the body works in harmony.
A primary regulator of our parasympathetic nervous system is the Vagus Nerve.
What is the Vagus Nerve?
This is a cranial nerve that connects the brain to the body. Its major role involves regulating your heart rate and keeping the gastrointestinal tract working optimally.
It integrates the central nervous system, immune functions and your lung function and gastrointestinal tract. Forming what is often called the gut-brain axis.
Stress inhibits the vagus nerve!
Commonly we see our clients not connecting the dots between their stress and their daily digestive movements. You may experience IBS, changeable bowel movements, nausea, reflux and burping and poor appetite.
Research published in the Journal of Cellular and Molecular Gastroenterology and Hepatology highlighted 40 years’ worth of literature showing how stress affects the structure of the bacterial community within our gut microbiome!
The exposure to social stressors for as little as just 2 hours showed changes in gut profiles as well as reduced numbers of certain species of beneficial gut bacteria.
Now for some science-y stuff
The signalling mechanisms from the gut to the brain happens via the neuro-immune and neuroendocrine pathways, which often involve the vagus nerve!
This communication happens via several molecules within the gut, including short-chain fatty acids (SCFA’s) as well as tryptophan metabolites (an amino acid essential for serotonin production) and bile acids.
The molecules send signals by interacting with several different cells that can cross the intestinal barrier, move into the systemic circulation and are even thought to cross the blood-brain barrier!
Research is still being made as to whether these molecules are reaching the brain directly or whether they are producing responses via neural signalling via the vagus nerve.
The microbiota can also produce or contribute to the production of many neuro-active molecules. One, in particular, is dopamine. (A neurotransmitter involved in our reward-motivated behaviour)
So what does it all mean?
Drawing attention to the fact that there is a strong link between your nervous system and your digestive system is the key to understanding how your mood impacts your gut.
We know from scientific research that stress indeed plays an integral part in the regulation of your nervous system and this is the master regulator of the Gut-Brain Axis.
Sarah is a qualified naturopath, nutritionist and herbalist with a special interest in men’s health & sports performance.