What Is the Gut-Brain Axis?

Learn what it is and why it could be important to your mental health

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The gut-brain axis is a system of two-way communication between the digestive system and central nervous system. Growing research suggests that the gut-brain axis, with a special focus on the health of the gut microbiome, can influence things like inflammation and disease, and even mental health.

Which Parts of the Body Make Up the Gut-Brain Axis?

When talking about the gut-brain axis, you might not realize all the parts of our body that are involved in this process of internal communication. There are three main areas of the body that are involved:

  1. Digestive system
  2. Brain
  3. Nervous system

Digestive System

Our digestive system, specific to the gut-brain axis, is referring to the entire gastrointestinal tract. This means from your mouth, through the stomach and intestinal tract, to the anus. It is a complex system with unique features that help us to break down the food we eat to digest them properly, which can mean the absorbing of nutrients as well as helping us to eliminate waste.

Microbiome

The microbiome refers to the world of our gut health and the bacteria, both good and bad, that live in our gut.

A large part of our microbiome is located within the intestinal tract and consists of trillions of microorganisms, mainly bacteria. This gut bacteria influences a lot of aspects of the body's functioning, like our metabolism, our weight, our immune system, and even our mood. When things are off balance within our gut microbiome it can result in inflammation and disease, as well as cause dysregulation of our mood by disrupting our neurochemistry.

Brain

It may seem obvious that the brain would be a primary component of the gut brain axis. However, it is important to note that neurotransmitters, chemicals that allow neurons to communicate with each other, are of particular importance when looking at the relationship between the gut and the brain.

Neurotransmitters synthesized by the brain influence things like our fight or flight responses and our mood. Poor gut health has been linked to a variety of mental health related concerns, including making people more susceptible to stress, anxiety and depression.

Nervous System

The human nervous system can be considered the body's command center. It is within the nervous system that communication throughout our body takes place, guiding our muscles and organs to function. The central nervous system and the enteric nervous system, which is part of the peripheral nervous system, are involved in the gut brain axis.

Central Nervous System

The central nervous system consists of the brain and the spinal cord. Information is carried through the body via electrical signals between neurons and responsible for receiving, processing and responding to sensory information.

Enteric Nervous System

The enteric nervous system is a large part of the peripheral nervous system and specific to our gastrointestinal system. Sometimes referred to as the gut brain or our second brain, the enteric nervous system is embedded in the gastrointestinal lining, starting in the lower part of the esophagus and ending at the anus. It directs movements of the gastrointestinal tract, regulates gastric acid secretion and gut hormone release, and interacts with the immune system in our gut.

The enteric nervous system is capable of functioning with or without input from the central nervous system.

Vagus Nerve

There is increasing research showing relationship between signals sent back and forth from the gastrointestinal tract to the brain by way of the vagus nerve. The vagus nerve is the longest and most complex of the cranial nerves, running from the brain, through the face and thorax, to the abdominal area.

It sends information about the state of our organs to our brain by way of afferent, or sensory, nerve fibers. It is the vagus nerve that might be considered the highway that information travels along as it goes back and forth from our gut to our brain.

How the Gut-Brain Axis Influences Mental Health

Researchers are interested in studying the association of gut microbiota to gastrointestinal diseases. The inflammation of the gut has been linked to mental health disorders such as anxiety and depression.

Gut bacteria produce hundreds of neurochemicals that the brain uses to regulate physiological functions as well as mental processes such as learning, memory, and mood. For example, it is suggested that the bacteria (microbiota) in the gut create about 90% of the body's supply of serotonin. Serotonin regulates many things including sleep, and body temperature, and is known to be a mood stabilizer.

As the gut microbiome becomes inflamed or there is an imbalance between the good and bad gut bacteria, also known as dysbiosis, signals are sent to the brain that can cross the blood-brain barrier. This, in turn, can result in someone experiencing increased stress, anxiety, or depression, among other things.

It is suggested that a balanced gut microbiome, which means that there are adequate good bacteria present, can help regulate or stabilize mood and work to help decrease feelings of anxiety and depression.

What Can Harm Your Gut Health?

The overall health of our gut microbiome is impacted by how much bad gut bacteria we have compared to varieties of good gut bacteria. Several factors can influence the health of our gut and this ration of good and bad bacteria, including food, antibiotics and lifestyle factors.

Food

Much of what influences the health of our gut is our diet. There are many foods that can inhibit the growth of good bacteria and encourage the growth of bad bacteria. Some of the foods that can disrupt a healthy gut microbiome include foods such as:

  • Refined carbohydrates
  • Sugar
  • Artificial sweetener
  • High fructose corn syrup
  • Fruits high in sugar (fructose)
  • Red meat
  • Fried foods
  • Soy
  • Dairy / lactose
  • Spicy foods

Antibiotics

In addition to the foods we eat, another culprit in the disruption of a healthy gut is the use of antibiotics. Although antibiotics are sometimes necessary to help us fight illness and infections, these medicines often kill all gut bacteria, including the good bacteria we need for a healthy gut.

Lifestyle Factors

Lifestyle can play a significant role in our overall health, to include the health of our gut microbiome. Additional factors that can negatively impact the integrity and health of our gut include:

  • Lack of physical activity
  • Smoking
  • Inadequate sleep
  • Stress

We experience much of these things on a regular basis, especially in our diet, our stress, sleep and the use of antibiotics. It might be of little surprise, then, that we can find ourselves struggling with physical and mental health issues if the quality of our gut bacteria can be so compromised by these common factors. The good news is there are things we can do to help improve the health of our gut.

How to Improve Your Gut Health?

Just as there are common, everyday things that can impact our gut health in a negative way, there are some easy ways we can work to help improve the health of our gut microbiome. These include the foods we eat and avoid eating, limiting the use of antibiotics when possible, taking quality pre and probiotic supplements and managing our stress levels and other lifestyle factors.

Diet

Since much of the makeup of our gut microbiome is influenced by diet, there is good news that we can take some simple steps to influence positive changes to our gut health in the foods we eat or don't eat. There are a variety of foods that can help us improve our gut health including:

  • Green tea
  • Yogurt with live active cultures
  • Sauerkraut
  • Almonds
  • Olive oil
  • Miso
  • Kefir
  • Pickled vegetables
  • Leafy greens, such as spinach and kale
  • Lean protein
  • Avocado
  • Low-fructose fruits, such as berries
  • Raw apple cider vinegar (preferably with the mother)

Supplements

Prebiotics and probiotics are found in many of the foods listed above, some that you may already include in your diet. However, there are also pre and probiotic supplements that can be taken to help aid in the growth of a variety of good gut bacteria and help create a healthier gut microbiome. You can find many supplements over the counter at your local grocery store pharmacy or online.

Manage Stress

Lifestyle factors, particularly stress, can disrupt our gut health and influence the signals being communicated in the gut-brain axis. Having a plan to manage stress can be particularly helpful in addition to monitoring diet and taking probiotic supplements. Effective ways to manage stress can include things like:

  • Yoga
  • Stretching
  • Meditation
  • Prayer
  • Physical activity
  • Being outdoors
  • Therapy
  • Journaling
  • Setting boundaries with others
  • Managing time well
  • Good sleep routine
  • Limiting social media
  • Talking with a friend

As we engage in these activities, we are allowing our bodies to receive and process signals of physical and emotional safety. In addition, the more we can effectively manage stress, the less we will likely turn to other unhealthy coping skills such as poor food choices and smoking, for example.

A Word From Verywell

The gut-brain axis is still an area being investigated by researchers from a variety of medical areas. Results have been promising to suggest that there are things we can do to influence the health of our overall gut microbiome and, in turn, improve the signals being communicated within the gut-brain axis. Although there is much more to learn, the implications for the future treatment of our mental and physical health are promising.

4 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Appleton J. The Gut-Brain Axis: Influence of Microbiota on Mood and Mental HealthIntegr Med (Encinitas). 2018;17(4):28-32.

  2. Järbrink-Sehgal E, Andreasson A. The gut microbiota and mental health in adults. Curr Opin Neurobiol. 2020 Jun;62:102-114. doi:10.1016/j.conb.2020.01.016

  3. Mark A. Fleming, Lubaina Ehsan, Sean R. Moore, Daniel E. Levin, "The Enteric Nervous System and Its Emerging Role as a Therapeutic Target", Gastroenterology Research and Practice, vol. 2020, Article ID 8024171, 13 pages, 2020. doi:10.1155/2020/8024171

  4. Terry N, Margolis KG. Serotonergic Mechanisms Regulating the GI Tract: Experimental Evidence and Therapeutic RelevanceHandb Exp Pharmacol. 2017;239:319-342. doi:10.1007/164_2016_103

Additional Reading

By Jodi Clarke, MA, LPC/MHSP
Jodi Clarke, LPC/MHSP is a Licensed Professional Counselor in private practice. She specializes in relationships, anxiety, trauma and grief.