by Samantha Key of Femma
Have you ever had a gut-feeling about something? Or get butterflies in your stomach when you’re nervous? This is a physical manifestation of the relationship of the gut-brain axis (GBA).
What is the gut-brain axis (GBA)?
The gut-brain axis (GBA) refers to the two-way link between the central nervous system (CNS) and the enteric nervous system (ENS). The CNS is composed of the brain and spinal cord and the ENs is composed of the sensory neurons, motor neurons and interneurons in the gastrointestinal (GI) system.
What does the GBA do?
The GBA is responsible for the two-way communication between the brain and the gut. This involves the interaction of the endocrine, immune and autonomic nervous system (ANS). Stress signals from the endocrine organs in the brain can affect digestion through the GBA. It is a back and forth feedback system of communication and gut microbes are involved in the transmission of these signals. These microbes also play a role in maintaining a healthy mood and influencing behaviour.
What is the microbiome?
The microbiome refers to the living organisms, the microbes that inhabit the gut. This includes both the friendly and the not so friendly microbes. The majority are symbiotic so the relationship between microbes and their humans is beneficial to both parties. A small amount are pathogenic, disease promoting. So, in a healthy gut the symbiotic and pathogenic microbes live in harmony.
What happens when the microbiome is unbalanced?
There are several factors that can cause the microbiome to become unbalanced with an overgrowth of pathogenic microbes or a depletion of symbiotic microbes. This can include dietary factors such as high sugar, fat or salt intake. This can cause inflammation of the gut lining leading to poor absorption of dietary nutrients. Some medications, stress, illnesses and infections can also cause inflammation of the gut lining which also leads to gut dysbiosis.
How does this affect mood?
Dysbiosis and inflammation of the gut has been linked to several conditions including anxiety, depression, Parkison’s and Autism spectrum disorders. As the symbiotic microbes in the gut are involved in the two-way communication between the gut and the brain, if the microbiome is in dysbiosis there can a negative impact on the signalling system
How do you restore balance to the microbiome?
Studies have shown that probiotics can favourably modify the gut microbiome , reduce inflammation in the gut lining, repair the intestinal barrier , modulate the HPA axis and produce neurotransmitters including serotonin and GABA. Serotonin is responsible for mood stabilisation and GABA helps to reduce nervous system activity. About 95% of serotonin is produced in the enterochromaffin cells in the gut, rather than in the brain.
Probiotics can be found from dietary sources such as yoghurt, kefir and fermented foods such as sauerkraut and kimchi. However, the amount and strain found in foods is not regulated as they are food products. Saccharomyces cerevisiae (boulardii) is a non-pathogenic yeast that supports gut health. It supports healthy immune function and can relieve symptoms of traveller’s diarrhoea. In terms of mood, it reduces the GI permeability and increases the absorption of nutrients as well supporting beneficial microbes. Additional benefits of this particular strain include, it is heat stable so does not require refrigeration and can be taken alongside antibiotics and antidepressant medications.