GUT – BRAIN AXIS
Can our gut and our intestinal microbiome affect mental health?
We have often used or heard the term “Gut Feeling” on our instincts. The research suggests that there is cross- talk between our gut and our brain also known as “Gut-Brain Axis”.
This blog post both shares our own personal experiences of a gut-brain and gut-body connection, but also some of the research on whether our gut health and microbiome can influence mental health and conditions such as depression and anxiety, and if probiotics might be helpful for some.
What Is The Gut-Brain Axis
Can Gut Health and Our Microbiome Affect Mental Health
I will share with you story of Tarun(name changed) who had some anxiety issues. Tarun loved to travel and he travelled in every 1-2 months before Covid 19 pandemic, but he noticed that he had abdominal discomfort in form of abdominal bloating and loose stools prior to every travel and it continued with his travel, these symptoms somewhat settled after he reached back home. He consulted a gastroenterologist for these symptoms and on evaluation was found to have positive breath test suggesting SIBO (small intestinal bacterial overgrowth). He was treated and his symptoms subsided, he did not experience similar symptoms during his future travels.
So how did his anxiety improved after treatment for gut problem. Is there any connection between Gut & Anxiety?
A study published in the reputable medical journal Nature Microbiology (year 2020) provides some of the strongest evidence yet to show that a person’s gut health and microbiome can influence their mental health. The authors used DNA sequencing to analyse microbiota in the faeces of more than 1,000 people enrolled in Belgium’s Flemish Gut Flora Project. The team then correlated different bugs with the participants’ quality of life and incidence of depression, using self-reported and physician-supplied diagnoses.
A systematic review of gut microbiota and major depression published in 2019 concluded:
“No consensus has emerged from existing human studies of depression and gut microbiome concerning which bacterial taxa are most relevant to depression. This may in part be due to differences in study design. Given that bacterial functions are conserved across taxonomic groups, we propose that studying microbial functioning may be more productive than a purely taxonomic approach to understanding the gut microbiome in depression.”
The challenge with research is that we are starting to understand the complexity and bioindividuality of humans. Could it be that there isn’t a standard microbiome that contributes to depression – imbalances in one persons microbiome are going to be different in another and thus perhaps we aren’t asking the right question?
Probiotics For Depression
Another layer of evidence demonstrating that our gut health and microbiome can affect our mental health comes from looking at the role of probiotics.
The conclusion of one paper is that “the evidence for probiotics alleviating depressive symptoms is compelling but additional double-blind randomized control trials in clinical populations are warranted to further assess efficacy“.
A systematic review concluded that: “probiotics were associated with a significant reduction in depression”
However not all research is positive. One meta-analyses concluded: “Probiotic supplementation has an overall insignificant effect on mood. Future studies should be conducted on more patients with clinically diagnosed depression”
In our personal experience we have found supplementation with probiotics seem to influence mood. But patients or users have experienced an overall improvement in wellbeing ultimately.
How Do Probiotics Work In Depression?
In terms of neurotransmission, several rodent studies found that consumption of probiotics prevented stress-induced increases in the hormone adrenocorticotropic hormone (ACTH), corticosterone, adrenaline, and noradrenaline.
The reduction in these markers of chronic stress suggests that treatment with probiotics attenuated the HPA axis, which is hyperactive in depressed patients. Consumption of probiotics was also shown to increase expression of brain-derived neurotrophic factor (BDNF), a growth factor crucial for brain plasticity, memory, and neuronal health that is abnormally reduced in patients suffering from depression.
Other preclinical studies have noted changes in the molecules involved in the biosynthesis and metabolism of the critical neurotransmitter serotonin.
Probiotics have also been shown to possess both antioxidant and free radical scavenging abilities, increase production of GABA, and improve absorption of other nutrients, all of which have been implicated in the pathophysiology of depression.
Research has also discussed probiotics modulating the inflammatory response. The available evidence suggests that “probiotics should be considered a promising adjuvant treatment to reduce the inflammatory activation commonly found in MDD.” Inflammation is a known contributory factor to depression.
Centre for Digestive care
To know more about Gut- Brain Axis, please contact Team CDC.