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Fish show link between anxiety relief and probiotics

Fish show link between anxiety relief and probiotics


Evidence that probiotics offer natural anxiety relief has come in a surprising way—a study about anxiety in fish.

A fascinating new study from the University of Missouri (MU) shows that fish anxiety levels are impacted by the bacteria in their gut.1  And there’s good reason to believe it’s the same for us humans.

You might be asking: “How can they tell if a fish is anxious?”

They have been studying anxiety medications using Zebrafish for quite a while—long enough that there are standardized ways to measure the fish’s anxiety level.

The researchers place a single fish into a new-to-them tank and monitor how much time it spends in the upper and lower parts of the tank.

It is surprising to me how much the anxious behavior in fish parallels anxious behavior in humans. Just like an anxious human may tend to be less outgoing and adventurous, anxious fish tend to spend more time in the bottom part of the tank and less time in the upper region.

The study

The MU researchers gave the test group of fish the probiotic bacteria Lactobacillus planetarium two times a day for a month before placing them individually into the observation tank.

Besides monitoring the level of anxious behavior exhibited by the test group and control group fish, samples were taken to examine gut bacteria present and neurotransmitter levels.

The results

The study results showed that the group given L. planetarium probiotics had

  • less anxiety, and
  • “up-regulation” of the pathways for the relaxing neurotransmitters GABA and serotonin

The researchers suggest that the friendly bacteria improved the action of the neurotransmitters and the neurotransmitters reduced the fish’s stress.

Humans have the same neurotransmitters and it is likely that we would have the same benefit from the probiotic bacteria L. planetarium.  


This study is part of an exciting and promising new field of research into the impact gut bacteria have on anxiety specifically and on mood in general.

The results are so encouraging that it has led to a new term: psychobiotics.

Psychobiotics are bacteria that have been shown to improve mental state including mood and memory.  

I’ll be writing more about Psychobiotics soon.

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  1. Davis, D. J., Doerr, H. M., Grzelak, A. K., Busi, S. B., Jasarevic, E., Ericsson, A. C., & Bryda, E. C. (2016). Lactobacillus plantarum attenuates anxiety-related behavior and protects against stress-induced dysbiosis in adult zebrafish.Scientific Reports,6.


Check out my books and hypnosis recordings for dealing with anxiety:

dealing with anxiety book

A quick look at Anxiety







natural remedies for anxiety hypnosis

 Discover Calm, Anti-Anxiety Hypnosis





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  • Ann Silvers
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