Evidence Mounts Linking Gut Bacteria to Your Mind and Mood

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There is bidirectional communication between your brain and gut. In fact, reputable scientists — like the father of neurogastroenterology and professor of Pathology and Cell Biology, Dr. Michael Gershon — believe you even have a second brain in your gut

Your gut is lined with over 100 million nerve cells, which is more than you have in your peripheral nervous system or your spinal cord. And, yes you have brain cells in your large intestines, which explains why the antibiotics that disturb your gut microbial ecosystem just may:

  • Interact with psychotropic medications
  • Cause neuropsychiatric effects
  • Influence your mood

It also explains why there's a high prevalence of mood disorders in those with irritable bowel syndrome. But, exactly what is the influence gut bacteria has over your brain, mood and emotions? 

This blog post explains.

Gut Bacteria's Influence on Your Brain

Chances are you've experienced "butterflies" or a "gut feeling" in your stomach. These sensations emanate from your stomach and suggest there's a connection between your gut and brain. Even more, studies show your brain impacts your gut health and your gut might even impact your brain health. This communication between the two is known as the gut-brain axis.

Your brain and gut are connected both biochemically and physically in various ways. There are 500 million neurons in your gut which connect to your brain through your nervous system's nerves.

Your vagus nerve is one of the largest nerves connecting your brain and gut and sends messages in both directions. Animal studies show stress hinders these messages sent through your vagus nerve and also leads to gastrointestinal issues.

In a study published in Gut, researchers found that mice bred to have zero bacteria in their gut, had an exaggerated stress response and that their ability to form memory were influenced by intestinal microbiota.

Gut Bacteria's Influence on Your Mood and Emotions

Science is putting together how the trillions of microbes that live in and on every person — the microbiome — impacts physical health. Even conditions like autism, neurodegenerative disease and depression are now being connected with tiny critters.

For centuries, it's been known how feelings can affect the gut. Consider what happens before a job interview or an exam. However, now it's being thought of as a two-way street.

Researchers feel they're on the cusp of a revolution that uses "psychobiotics" or "mood microbes" for improving mental health. One study in particular shows "germ-free" mice that haven't come in contact with microbes had pumped twice as much stress hormone than normal mice when distressed. The animals were identical with the exception of their microbes. The study strongly indicated the difference was due to their microorganisms.

Ninety percent of your serotonin receptors are in your gut, reports Harvard Health Publishing in nutritional psychiatry, which is a fairly new field, patients are shown how diet and gut health can negatively or positively impact their mood. When an individual is prescribed a selective serotonin reuptake inhibitor (SSRI) or another type of antidepressant, the most common side effects they experience are gut-related and many individuals temporarily experience:

  • Diarrhea
  • Nausea
  • Gastrointestinal issues

One study published in Molecular Psychiatry revealed avoiding inflammation-producing foods and eating a balanced, healthy diet like the Mediterranean diet could provide protection against depression

Nature Microbiology published study suggested that individuals who have clinical depression could be affected by the amounts of their gut bacteria

Another study published in the American Journal of Public Health revealed that improvements in psychological wellbeing happen after increasing the intake of fruits and vegetables. The study authors liken the psychological wellbeing improvements to that of going from being unemployed to employed.



The more researchers find out about gut bacteria, the more they're coming to realize how they could potentially affect every facet of our lives, and not just our well-being and physical health, but also our emotions and thoughts.

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