Author: Sara Habibipour
On this platform, we've previously talked about the importance of the gut microbiome when it comes to colorectal health, inflammatory, and immune diseases (read more here and here!), but I've recently learned something really extraordinary; probiotics are not just relevant to gut health. They actually extend beyond just the physical. Research has shown that an imbalance of the microbiome is connected to mental illness, particularly anxiety and depression. This field of research has been coined the term "psychobiotics," or the use of probiotics to treat mental health conditions.
Let's first review the connection between the gut and the brain.
In the past decade, researchers have begun to call the gut as “second brain" due to the large amount of nerves present in the gut. The main nerve that connects the brain and gut is called the vagus nerve, which is the main nerve of the parasympathetic nervous system, which plays a key role in mood regulation, heart rate, digestion and immunity. Because of this, there is a lot of neural activity in the gut including serotonin, dopamine and GABA, which are three neurotransmitters directly related to anxiety and depression. In fact, quite shockingly, the gut produces more than 90% of the body’s serotonin (Forbes Health).
Because there's so much neural activity in the gut, it makes sense that gut bacteria impact mental health. One study in mice found those given probiotics with the bacteria strain Lactobacillus rhamnosus were less stressed and anxious than mice that weren’t given probiotics. However, they also note that they lack certainty, and this study is further limited by its use of mice subjects rather than human participants; obvioulsy, mice cannot express verbally if they are feeling anxious, depressed, etc. But, behavior-wise, there was a clear difference between the control and treatment groups.
Experts in the subject don't believe that psychobiotics are a cure-all for depression and anxiety; in other words, you can't take a probiotic every morning and expect for all your problems to go away. But, they do say that psychobiotics seem to play a role in mental health, particularly in the form of probiotic foods versus supplements. Probiotic supplements tend to be more expensive than probiotic-rich foods, so this could be a fairly accessible research-based method to improving mental health, as well.
Psychobiotics seem promising. However, more high-quality human clinical studies are needed to learn more about the gut-brain connection, as well as their full scientific benefit to improving mental health. I hope to see more findings and publications on this subject in the near future!
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Sources:
https://www.forbes.com/health/body/psychobiotics/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7767237/
https://www.apa.org/monitor/2018/12/cover-psychobiotics
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