Mental and Physical Health: The Gut Plays a Larger Role Than We Once Thought

The scientific community has acknowledged the connection between physical health and bacteria in the gut. On the other hand, the role the gut plays in mental health has been less understood and researched.

However, results of recent studies show the gut plays a larger role in health — both physically and mentally. Neuroscientists are now taking an interest in gut bacteria, including its link to common physical and mental health diseases and what this link could mean for experimental design.

Neuroscience Taking Notice

In 2014, the U.S. National Institute of Mental Health spent over $1 million on new research aimed at better understanding the gut bacteria-brain link.1 While there have been connections made between the gut microbiome and mental health and behavioral conditions, neuroscience is just beginning to uncover how it all links together.

Neuroscientists are studying how levels of stress hormones and symptoms of anxiety and depression of mice are affected by changes in gut bacteria. They found that a mouse model exhibiting features of autism had significantly higher levels of a particular bacterial metabolite. They also found that after injecting this same metabolite into normal mice, these mice then exhibited the same symptoms.1

The Right Bacteria May Reduce Anxiety

In a recent study based out of England, 45 healthy participants ages 18 to 45 took a prebiotic or placebo every day for a total of three weeks. At the end, the scientists tested the participants’ reaction to computer tests, as well as their cortisol levels.

The study found that individuals who took the prebiotic experienced less anxiety when subjected to threatening or negative stimuli. The participants also had lower cortisol levels in their saliva. High cortisol levels have been linked to depression, stress and anxiety.2

How Bacteria in the Gut Can Affect the Whole Body

Scientists are hypothesizing that intestinal bacteria can alter mental health.1 When the intestinal wall allows toxins to seep into the body from the gut, these toxins may be causing an immune system response, which sets off the brain’s reaction.3

Research has also shown that the vagus nerve plays a key role in the communication between the gut and the brain. Bacteria can use this nerve, which links the enteric nervous system to the central nervous system, to signal brain activity and changes.4

In addition, preliminary evidence shows immune cells play a role. Almost 70 percent of our immune system is located in our digestive tract. It is in constant circulation between the digestive tract and the rest of the body.4

This infographic, which first appeared in a Huffington Post article by Carolyn Gregoire, highlights a number of physical and mental health issues that research has now linked to the gut:

How Gut Bacteria Affects the Brain & Body

What You Can Do to Feel Better Overall

While we may not yet understand exactly how the gut-brain-body connection works, we do know there is a connection. Start improving how you feel by incorporating prebiotics and probiotics into your diet. They will create a better balance of bacteria in your gut.


  1. Reardon, Sara. “Gut–brain link grabs neuroscientists.” Nature International Weekly Journal of Science. Nature Publishing Group, a division of Macmillan Publishers Limited, 13 November 2014. Web. 18 February 2015.
  2. Rettner, Rachael. “Gut Feeling? Probiotics May Ease Anxiety and Depression.” Live Science. Purch, 24 December 2014. Web. 18 February 2015.
  3. Fang, Janet. “Gut Bacteria May Affect Mental Health in Humans.” IFLScience, 31 December 2014. Web. 18 February 2015.
  4. Wernick, Adam. “Bacteria in our gut may influence both our physical and mental health.” PRI Public Radio International, 08 September 2014. Web. 18 February 2015.

1 comment

  1. Zillah says:

    love this information! will definitely share this!

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