The World Microbiome Day 2021 highlights that microbes are important in preserving the long-term health and sustainability of our society and planet. Not only can microbes protect our environment, but they also keep us healthy by fending off intruding pathogens. However, it becomes clear how our psychological health is also affected by the microbes living in and on our bodies. To celebrate World Microbiome Day, Sarah Wettstadt gives a glimpse of what we know about the link between the gut microbiome and mental health and how we can improve both. #FEMSmicroBlog #MicrobiologyIsEverywhere
Microbial communities impact our health
Our bodies are covered in microbes – both on the inside and the outside. These microbes change depending on the niche of the body and the local conditions.
Generally, commensal microbial communities fend off incoming pathogens improving the health of the local body niche. When the number and composition of beneficial commensal microbes are disrupted, the resulting dysbiosis can have serious effects on our health.
Commensal microbial communities in and on our bodies fight pathogenic intruders and keep us healthy.
For example, the oral microbiome fights pathogens like Porphyromonas gingivalis. These can otherwise cause periodontitis, a disease that destroys the tissue around your teeth. Similarly, a dysbiosis of the vaginal microbiome can result in the growth of vaginosis-causing microbes.
However, depending on the site of residence, local microbiomes can have additional functions. Most importantly and best characterised is the gut microbiome and its support in food digestion. This local microbial community metabolises otherwise unbreakable substrates and produces molecules that are important for our metabolism.
Now, research shows how the gut microbiome and its products also affect our mental health. As such, dysbiosis of the gut microbiome can even result in psychological disorders like anxiety or depression.
About the communication between the microbiome and the brain
The microbiota–gut–brain (MGB) axis represents the bidirectional communication between the brain and the gut microbiota. Many factors influence this interaction: the immune system and its chemokines and cytokines; metabolic pathways and metabolic products as well as the central nervous system and its stress hormones and neurotransmitters.
Different bacterial species can metabolise these hormones, metabolites and neurotransmitters in the gut. Additionally, stress and emotions affect the secretion of gastric acid, bile and mucus. Together, these factors alter the environment for microbes and thus the composition of the gut microbiome.
On the other side of the MGB axis, gut microbes produce metabolically active compounds like short-chain fatty acids. These cross the epithelial cell layer and modulate gene expression, neurotransmitter signalling and metabolism. Thus, a change in the microbiome composition can influence our emotions and stress behaviour.
A change in the composition of the gut microbiome can influence our emotions and behaviour.
Your behaviour shapes your gut microbiome shapes your mental health
Many factors like diet, physical exercise, drug treatment or geographical location impact the gut microbiome composition. By shaping the gut microbiome and thus the produced metabolites, these factors also influence our mental health status and behaviour.
For example, studies investigated the effects of foods that contain probiotic strains like Bifidobacterium infantis, B. longum, Lactobacillus helveticus ROO52, L. rhamnosus JB-1 or L. casei strain Shirota. These probiotic foods were shown to reduce depressive- and anxiety-like behaviour, memory dysfunction and even physical symptoms during stressful periods.
Also, prebiotics like fructooligosaccharide and galactooligosaccharide have similar impacts on our mental health and cognitive behaviour. Researchers claim that prebiotics increase the relative abundance of beneficial microorganisms and thus shape the MGB axis.
We can influence our gut microbiome and mental health with more than food. For example, physical exercise not only helps the immune system and metabolism. It also leads to a richer gut microbiome that helps metabolise lactic acid from the muscle to produce more short-chain fatty acids.
On the contrary, increased alcohol intake or chemotherapy can have opposite effects on our mental health. These compounds harm the epithelial layer of the gut resulting in gut leakiness and inhibited microbial adherence. This changes the gut microbiota and can lead to an increased risk for psychiatric disorders, depression and anxiety.
Celebrate your Microbiome Today!
Microbial communities across our bodies play vital roles in our physical and psychological health. By taking care of our gut microbiome, we finally shape our own mental health and cognitive behaviour.
It seems that the phrases “You are what you eat” and “Eat what makes you happy” were always true. It is just now that we start to understand why.
So, today marks the day you should celebrate your microbiome and be grateful for keeping you healthy – both mentally and physically!
Happy World Microbiome Day!
Dr Sarah Wettstadt is a microbiologist-turned science writer and communicator working on various outreach projects and helping researchers talk and write about their scientific results. Her overall vision is to empower through learning: she shares scientific knowledge with both scientists and non-scientists and coaches scientists in writing about their research. Sarah is blog commissioner for the FEMSmicroBlog and was a social media editor for FEMS for 1.5 years. Previous to her science communication career, she worked as a postdoc in Marían Llamas’ lab on Pseudomonas aeruginosa’s ability to use heterologous iron sources and completed her PhD with Alain Filloux investigating the type 6 secretion system in Pseudomonas aeruginosa.
About this blog section
The section #MicrobiologyIsEverywhere highlights the global relevance of microbiology. The section acknowledges that microbiology knows no borders, as well as the fact that microbiologists are everywhere and our FEMS network extends well beyond Europe. This blog entry type accepts contributions from excellent blogs translated into English. Regional stories with global relevance are welcomed. National or international events sponsored, organised or connected to FEMS are also covered.
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