How Gut Bacteria Can Affect Anxiety


It has long been understood that anxiety and depression are linked with our gut bacteria. Now scientists believe they have discovered tiny molecules in the brain that may be used by our gut bacteria to influence our emotions.

Our microbiome – made up of 100 trillion bacteria – has long been understood to have some influence over our mood and our mental health, but scientists have been unsure of exactly how.  

Now a new study of mice suggests that gut microbes may alter microRNAs — which are molecules that help keep cells in working order in the parts of the brain that control feelings of anxiety. The study which was published in Microbiome, could enable scientists to develop treatments for anxiety and other related mental health problems.

This research comes on the back of other exciting results into our gut microbiomes role in influencing our mental health.  In one early study the presence or absence of certain gut bacteria was found to influence whether a mouse exhibits symptoms of anxiety, such as avoiding bright lights or open spaces.

The Findings

The researchers found that in certain microbe-free mice, the parts of the brain associated with controlling anxiety — the amygdala and prefrontal cortex had an overabundance of certain types of microRNA compared with normal mice. When these mice were subsequently exposed to microbes, the microRNA levels more closely matched those of normal mice.

In a related study, the microRNAs in the amygdala and prefrontal cortex of rats were examined after the rats gut bacteria had been heavily treated by antibiotics to kill off the microbiomes. This had a similar effect on the rats microRNA levels as was seen in the microbe-free mice.

The researchers conclude that gut bacteria may affect the anxiety levels of their host by affecting the microRNAs in specific parts of the brain, however they still aren’t sure how they can do this.

Whats next

As a follow on from this study the team hope to cultivate certain types of bacteria in the gut, in order to influence microRNA levels in specific parts of the brain which could lead to the development of new medications for psychiatric and neurological disorders.


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