Could our microbiome impact our mental health?
- audrone8
- Jul 25
- 3 min read
Updated: Sep 3
Author: MD Rugile Kancaite
When considering the things that may affect mental health, most people probably don’t think that among factors like the environment or genetics [1], trillions of microbes living in the gut - also known as our microbiome - may actually play an important role in dictating how we feel.
Increasing evidence suggests that the bacteria in the gut, as well as their byproducts, may affect the human mood, cognition, and behavior [2] - and while this may sound like rocket science, we’re here to break it all down.
How does the gut and the brain communicate?
The gut and the brain are linked by the gut-brain axis - a system that allows constant bidirectional communication between the two, influencing the processes in each, at first glance very individual, networks.
You might’ve already heard about the vagus nerve - the longest nerve in the human body [3]. It’s also one direct link that connects the brain and the gut, among endocrine (hormonal), immune, and metabolic system pathways, together making up the gut-brain axis [2].
What is the gut microbiome, and what does it have to do with our brain?
The gut microbiome is the collection of all microbes, such as bacteria, viruses, fungi, and their genes, that naturally live inside of our bowels. And while a person’s microbiome is mainly formed early in life, it can change over time in response to different factors, including our dietary choices [5].
Currently available scientific evidence shows that these microorganisms may impact the overall human health - including its mental aspects - in many ways. Scientists have identified more than two thousand different types of microbes within the human gut [6], which produce different molecules that signal various processes involved in the gut-brain axis.
The gut and mental health: what do we know so far
One of the ways the microbiome is able to have a potential impact on our mental health is by responding to the neurotransmitters from the brain, as well as producing some of those involved in regulating thoughts and emotions, such as serotonin and dopamine, both known as the “feel-good” hormones [2].
In fact, it’s been shown that the microbes living in the gut may be responsible for producing 95% of serotonin [7], which plays a role in regulating human behavior, mood, memory, among other bodily functions [8].
To add, the gut microbiota is shown to affect the hypothalamic-pituitary-adrenal (HPA) axis, which is involved in managing stress response, as well as by partly controlling the inflammation processes associated with multiple mental illnesses [9].
Emerging evidence allows scientists to think that disturbances in the gut microbiota and brain-gut communication may contribute to the development and worsening of several mental health disorders, including anxiety and depression [6].
While there’s much we still don’t know about how certain gut microbes may influence our mental health, a recent systematic review has suggested that people with depression might have reduced diversity of gut microbiota and higher levels of Firmicutes bacteria, those living with anxiety were associated with low levels of short-chain fatty acid (SCFA)-producing bacteria, as well as higher levels of Proteobacteria; whereas it’s been suggested that people with schizophrenia might have a reduced count of Lactibacillus, and those with bipolar disorder have shown altered ratios of Firmicutes and Bacteroidetes [9].
What does this mean to us?
While these findings are relatively new, they seem to be promising in helping scientists discover new approaches to managing mental illnesses. For example, psychobiotics (probiotics with effects on the brain) are being investigated as potential additional therapies for helping manage mental disorders [6].
Additionally, while gut inflammation may play a role in mood issues, targeting inflammation through dietary changes, probiotics, or anti-inflammatory drugs could eventually become important management strategies [6].
In the meantime, it’s practical to know that our diet influences our gut microbiota, which in turn may affect our mental health. Research shows that eating healthy whole foods - including fermented and fiber-rich foods - may support beneficial microbes that might help enhance well-being, while processed foods promote harmful ones linked to mood issues [2, 9].
Some of the examples of foods known to be potential sources of beneficial gut microbes include fermented foods, such as yogurt, kimchi, sauerkraut, kefir, and kombucha; whereas dietary fibers found in fruits and vegetables “feed” the beneficial bacteria in the gut and promote greater microbiome diversity [6].
However, it’s important to note that though diet may be helpful in managing several mental health conditions, it’s by no means a substitute for professional medical care, serving as a complementary approach to traditional treatments.
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