The brain in your gut
Many of you are aware of the connection between gut health and mood disorders.
I do talk rather a lot about the enteric nervous system. We have the central nervous system, that is our brain and spinal cord, and we have our enteric nervous system which sits in our gut and produces the same neurotransmitters as our brain.
Biochemical signalling between the gastrointestinal tract and the central nervous system is otherwise know as the gut-brain axis. There has been a significant amount of progress in recognising the importance of this bi-directional relationship with researchers exploring how the microbiota influences mood disorders.
Stress and mood disorders show high comorbidity with gut conditions such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), suggesting that stress changes may influence gut-brain dysfunction and visa versa. In major depressive disorders, reduced microbial diversity has been reported and in bipolar, this reduction correlates with illness duration. Therefore stress-induced dysbiosis can further perpetuate mood disorder severity.
Key findings show that gastrointestinal bacteria directly synthesize neurotransmitters such as serotonin, GABA, histamine, adrenaline and Brain Derived Neurotrophic Factor (BDNF), a key molecule involved in plastic changes such as memory and learning.
Stress also increases intestinal permeability (leaking gut) which allows gram-negative bacteria to cross the mucosal lining of our gut, resulting in the activation of the immune system and the subsequent production of inflammatory mediators (a double whammy!).
Therefore, probiotics play a vital role in treating and preventing mood disorders. They competitively exclude gut pathogens, reduce inflammation and communicate with the central nervous system leading to changes in neurotransmitter function. However not all probiotic species are beneficial in all circumstances. As I am sure you all know there are two main genera of beneficial bacteria, Lactobacillus and Bifidobacterium. (All who have completed the delightful complete digestive stool analysis [CDSA] will know about these guys!) And there are many sub-species within these two large groups.
Lactobacillus helveticus has been characterised for its ability to adhere to human intestinal epithelial cells, block the invasion and translocation of pathogenic bacteria and to down-regulate pro-inflammatory pathways.
Bifidobacterium longum has been shown to help maintain intestinal barrier integrity, interferes with the inflammatory response and exert positive effects on the vagus nerve. (This nerve delivers information from the gut to the brain.)
There are several probiotic formulations now produced which contain these two very specific strains and have been clinically trialed for stress and mood support.
Probiotics never cease to astonish with their enormous ability to positively affect all bodily systems and treat a plethora of health concerns!
