Can Bacteria Talk To Your Brain?

Our brain and digestive system are intimately linked

So closely, in fact, that many experts say it should be viewed as one system. The gut is often referred to as “the second brain” and contents of this second brain can profoundly affect our first. Bacteria in our digestive systems may help mold brain structure as we’re growing up, and possibly influence our moods, behavior and feelings when we’re adults. The ability of our gut to bidirectionally communicate with the brain (gut-brain axis) is at the forefront of current research.

In just one person’s body, microbes are estimated to weight between 2 and 6 pounds…that is twice the weight of the average human brain. Up to 40% of the population has functional bowel problems at some point. The human body contains 100 trillion microbes that make up the microbiome. At least 70% of the immune system is aimed at the gut to expel and kill foreign invaders.

The Vagus Nerve

90% of the fibers in the primary visceral nerve, the vagus nerve, carry information from the gut to the brain…and not the other way around. The vagus nerve is believed to be a direct neuronal connection between the gut and the brain. One study in Ireland looked at the vagus nerve in mice. When the cut the vagus nerve, researchers no longer saw the brain respond to changes in the gut.

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Good vs. Bad Bacteria

The good gut bacteria interact on a hormonal level, helping to turn off the cortisol and adrenaline response that can cause long-term harm to the body. Good bacteria are at war with bad bacteria. An imbalance of beneficial versus harmful gut bacteria (known as dysbiosis) has been linked to numerous psychological disorders.

The gut appears to help maintain brain function and has been increasingly proven to influence the risk of psychiatric and neurological disorders, like autism, anxiety, depression, and stress. The gut even plays a role in neurodegenerative diseases like Alzheimer’s disease and Parkinson’s disease.

Experiments in mice found changes in both brain chemistry and behavior. One experiment involved replacing the gut bacteria of anxious mice with that of fearless mice. They found that the anxious mice becomes less anxious and more sociable. It also worked in reverse…bold mice became timid when they received the microbes of anxious mice. Aggressive mice even calmed down when the scientists altered their microbes by changing their diet and feeding them probiotics.


The microbiome communicates with the brain through molecules that are produced by gut bacteria and then enter the bloodstream. These molecules are strong enough to change behavior.

The immune system

Microbes in the gut interact with the immune system. This in turn communicates with the brain, setting up a channel of communication between the gut and the brain.

The blood stream

Blood releases both neuroactive compounds and hormones. These enter the bloodstream, which then goes to the brain.

Research shows us that people suffering with GI disorders are more susceptible to anxiety-related disorders. Anthony L. Komaroff, the Editor in Chief of the Harvard Health Letter, stated that “a person’s stomach or intestinal distress can be the cause or the product of anxiety, stress, or depression. This is because the brain and the GI system are intimately connected – so intimately that they should be viewed as one.”

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You may also like: 7 Signs You Need Probiotics

Create a healthy gut environment.

Creating a healthy gut environment may help ease your mind. Probiotics are often called “good” bacteria because they help keep your gut healthy. They are found in many different foods (sauerkraut, miso, yogurt, kefir, kombucha) and probiotic supplements. Prebiotics are substances that induce the growth or activity of good bacteria that contribute to well-being. Prebiotics can be found in foods like asparagus, garlic, bananas, and apples, and prebiotic supplements. Here is what a healthy gut environment will do for you:

  • Stimulate the digestive process.
  • Aid in absorption of nutrients.
  • Help provide gut wall resistance to reduce leaky gut syndrome.
  • Prevent growth of harmful bacteria.
  • Break down poorly digestible foods (like dietary fiber).

Today’s researchers are beginning to understand the amazing role of gut bacteria in mental well-being. Balance your mind by first balancing your gut.

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 SOURCES:  [1] [2] [3] [4] [5] [6] [7] [8] [9] [10]


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