The Brain-Gut Connection

The Brain-Gut Connection

I find this hard to swallow...

I cannot stomach that any longer...

I feel butterflies in my stomach…

These are commonly used expressions. You may have used them yourself. Have you thought about what they mean or why we use them? It has to do with the brain-gut connection

What Is the Brain-Gut Connection?

The brain-gut (or gut-brain) connection is a very complex communication system between the brain, which is part of the central nervous system, and the GI system, where the enteric nervous system is embedded. This bidirectional communication system explains the relationship between a person’s stress level and emotions, brain functions, and gastrointestinal (GI) system. In this 2-way system, emotions and stress affect the GI system and the GI system affects emotions.

We’ve known that anxiety, stress, and depression contribute to gastrointestinal conditions like IBS. Newer evidence indicates that it may also be the other way around. IBS is associated with an imbalance of bacteria in the gut. This imbalance signals the brain and triggers mood changes. These findings may explain the association between IBS and other functional bowel problems (like some constipation, diarrhea, and bloating) and anxiety or depression. 

It also involves the hypothalamic-pituitary-adrenal axis, the nerves of the autonomic nervous system, and the gut microbiota.

Components of the Brain-Gut Connection:

  • Gut = Gastrointestinal (GI) System

  • Central Nervous System (CNS) = Brain and Spinal Cord

  • Enteric Nervous System (ENS), called the Second Brain = Network of nerves embedded in the tissue of the gut (digestive tract)

  • Autonomic Nervous System (ANS) = Pathway between the CNS and body organs. Has 2 parts:

    • Sympathetic (triggers body processes during stressful or emergency situations; known as fight or flight)

    • Parasympathetic (slows and controls body processes during ordinary situations, known as rest and digest)

  • Hypothalamic-pituitary-adrenal (HPA) connection, part of the endocrine system = Hormonal pathway involving 3 glands: the hypothalamus, pituitary gland, an adrenal glands.

    • Glands produce hormones (the body's chemical messengers). The HPA connection coordinates the body's responses to stress.

  • Gut microbiota = Systems of trillions of different microorganisms in GI tract. The gut microbiota is critical to good health - e.g. impacts immune function and metabolism of nutrients

How Does A Healthy Brain-Gut Connection Work? 

When the brain-gut connection is working well, both the brain and intestines are healthy.  

  • A person is, generally, in control of their emotions and able to deal with stress. 

  • Overall, the gut microbiota functions well, inflammation is well-controlled, and hormone levels are in a normal range.  A person’s GI system is disease-free. 

The brain supports a well-functioning gut and a healthy GI system positively affects emotions.

What Happens When There Are Problems With The Brain-Gut Connection?

When this connection is not working well, it may result in abnormal brain and GI tract functioning. 

  • A person may have heightened stress and anxiety or other unhealthy emotions, such as sadness, anger, or fear. 

  • They may have an unhealthy GI system due to microbiota changes, increased immune response, or heightened pain sensations. And, they may have disorders like irritable bowel syndrome (IBS). 

As an example, increased stress in a person with IBS often causes their symptoms to worsen.

Maintaining A Healthy Brain-Gut Connection?

Lessening stress, anxiety, and other negative emotions helps keep the brain and gut healthy. And, keeping a healthy microbiota does the same.  But, what can you do to support your brain, gut, and the connection between them?

Reduce Stress And Anxiety

The following help lessen stress and anxiety, thus improving gut health:

  • Mind-body techniques like yoga, relaxation and deep breathing, and journaling

  • Regular exercise and physical activity

  • Certain herbal supplements

  • Spending time with friends, family, and pets

  • Taking breaks from the news, social media, and other stress-filled information sources

  • Counseling or therapy

Keep Your Gut Healthy

The following help to keep your gut healthy, thus your brain:

  • The Mediterranean Diet 

  • A diet that includes  fiber, fermented foods, and probiotics  

  • Certain medicines and supplements, like fiber and probiotics

  • Meditation and physical activity

For More Information

American Academy of Family Physicians (2020). Fiber: How to Increase the Amount in Your Diet. Retrieved 10-6-2020 from

American Academy of Family Physicians (2020). Probiotics. Retrieved 10-6-2020 from

American Academy of Family Physicians (2020). The Mediterranean Diet. Retrieved 10-6-2020 from

American Gastroenterological Association (2020). Irritable Bowel Syndrome (IBS).  Retrieved 10-9-2020 from 

International Food Information Council (2020). Gut Check: Fermented Foods and the Microbiome. Retrieved 10-6-2020 from