New Meaning Behind “Trust Your Gut”: How Our Stomach Affects Behavior

Second Brain In Your Gut

Did you know you have a second ‘brain’ in your gut? Did you also know that Inflammatory Bowel Diseases increase your risk for depression, anxiety, and other mental health issues? This is because our gut brain and our ‘real’ brain are far more interconnected than previously known. The connection between microbes in our intestinal tract and our brain has been termed the “microbiota-gut-brain-axis.”

Photo Credit: New Scientist

Behavior Driven by Gut Contents

Since at least 2015, we have shown in rodents that behavior can be transplanted. By transplanting the gut contents of rodents we have been able to physically observe behaviors linked to certain microbes. Some studies simply took gut contents of shy mice and placed them in outgoing mice. The shy group became outgoing and vice versa. Brain changes were also noted in rodent studies.


What the Science Means in ‘Real Life’

Why does this matter? Because we are now seeing significant evidence from pre-clinical studies that the gut microbiota (an ecosystem of microbes) can affect behavior. So what is going on in your pet’s stomach, can affect their behavior(s). The studies are still in the early phases but it is being hypothesized that probiotics can help with canine aggression and anxiety.

This paper was discussed at the recent American Veterinary Medical Association (AVMA) conference. “The adoptive transfer of behavioral phenotype via the intestinal microbiota: experimental evidence and clinical implications.” Essentially it showed once more that in rodents…

  1. Behavior can be transferred between animals.
  2. Behavior changes alter brain chemistry.
  3. Intestinal bacteria or their byproducts may be used to treat central nervous disorders.

This is amazing research to follow closely! It could improve the lives of animals and humans drastically. Especially since we do not understand IBS or IBDs in animals. We cannot wait to see more studies.



  1. Harvard Healthbeat: The gut-brain connection.
  2. Johns Hopkins Medicine: The Brain-Gut Connection.
  3. Scientific American: Gut Feelings-the “Second Brain” in Our Gastrointestinal Systems.
  4. Gastroenterology & Hepatology
  5. Nature: Behavioral Transplants
  6. Current Opinion in Microbiology: The adoptive transfer of behavioral phenotype via the intestinal microbiota: experimental evidence and clinical implications.
  7. Nature; Neuropsychopharmacology: More than a Gut Feeling: the Microbiota Regulates Neurodevelopment and Behavior.
  8. New Scientist: Two Brains in One Body.
  9. Psychology Today (blog): The Pit In Your Stomach is Actually Your Second Brain.
  10. The Bowel and Beyond (scientific journal)
  11. The Enteric Nervous System (scientific journal)
  12. Database of scientific journals on the Enteric Nervous System

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