Uncovering the Gut-Brain Connection



More than just a regretful late-night trip to get fast food, did you know that your gut health could affect your mood and behavior?


Scientists have known there is some connection between gut health and mental health since the early 1900s. Scientists and doctors emphasized the relationship between the two but by 1930, opinions reversed and it was thought that mental health disorders influenced gastrointestinal disorders. However recent research in the area of gut health has revealed that there is a close relation between behavioral issues, mood, and an underlying bacterial imbalance.


Even though there are a number of factors that influence the condition of your gut microbiota and its environment, your diet is a major one. Immune system health is a close second. All of this points to the strong indicator of how critical what we eat is to not only our physical health but our mental health as well.


Recent research in the area of gut health has revealed that there is a close relation between behavioral issues, mood, and an underlying bacterial imbalance

Let’s get a little science-y for a bit here. Your gut is connected to your brain in three ways: the vagus nerve, the enteric nervous system, and the gut-brain axis.

  • The vagus nerve runs from your brain stem down into the neck, thorax, and abdomen and supplies motor parasympathetic fibers to all the organs except the adrenal glands. It helps regulate heart rate, speech, sweating, and various gastrointestinal functions.

  • The enteric nervous system connects with the central nervous system (CNS) and has local and central sensory neurons in the gut wall that monitor the conditions. There are other local circuit neurons that integrate the information and make it so the motor neurons regulate the activity of the smooth muscles in your gut wall as well as glandular secretions like digestive enzymes, mucus, stomach acid, and bile. It is referred to as the “second brain” because it can operate by itself and communicate with the CNS.

  • The gut-brain axis links the emotional and cognitive centers of the brain with the peripheral intestinal functions. Evidence from animal studies suggest that gut microorganisms can activate the vagus nerve and has a critical role in mediating effects on the brain and your behavior.

Bacteria and anxiety and depression have interactions that go both ways. A 2009 study found that male pup rats’ microbiota was altered when they were stressed from being separated from their mother. While they were only separated for three hours a day for 11 days, it was enough for researchers to conclude that it might make them more vulnerable to disease later in life, like depression or irritable bowel syndrome.


Your gut microbiota influences serotonin and dopamine production – your “feel good” chemicals. Did you know that over 90 percent of your serotonin is found in your gut? Well, it is, and it is a key regulator of gastrointestinal motility. The enteric nervous system uses more than 30 neurotransmitters, including serotonin, dopamine, and acetylcholine.

Some depressed rats were used in a 2014 study and given a strain of probiotics which resulted in a reversal of negative behavior and balance of the immune system. The probiotics had a positive therapeutic effect on the anxiety and depression symptoms of the rats.

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