What is the Gut-Brain Axis?

Aug 22, 2023 | Mind-Body

The gut-brain axis (GBA) is the connection between the central nervous system (CNS) in the brain and the enteric nervous system (ENS) in the gut.

We’ve always know the brain sends information to the gut. But we recently discovered this communication is bidirectional. The gut (gut and microbiome) also sends important information the brain!

The scientific name for this type of bidirectional communication is “microbial endocrinology” or “inter-kingdom signaling.” Essentially, it is a symbiotic and pathogenic relationships between the bacteria and mammalian host.

Surprisingly, the gut and brain are connected via multiple communication pathways. Let’s dive into the details now.

Cryan, J., Dinan, T. More than a Gut Feeling: the Microbiota Regulates Neurodevelopment and Behavior. Neuropsychopharmacol 40, 241–242 (2015). https://doi.org/10.1038/npp.2014.224


The vagus nerve (and GI tract nerves) physically connect the gut and brain. This also includes modulation of the intestinal and blood-brain barrier (BBB) permeability.


The HPA axis (hypothalamic-pituitary-adrenal) and hormone metabolizing microbes endocrinologically connect the brain and gut.


The brain and gut are also connected through production of metabolic mediators and signaling molecules.


The gut-associated lymphoid tissue (GALT) connects the gut and brain immunologically, as well as response to immune mediators and microglial activation.


These pathways combine through the HPA axis and the autonomic nervous system to create the GBA. This allows the gut to influence mood, cognition, and mental health. And the brain to influence intestinal activities such as motility, immune activity, and serotonin metabolism.

The gut microbiome directly and indirectly impacts the brain’s emotional and cognitive activity. In fact, fluctuations in the microbiome are associated with the following:

  • Mood disorders (e.g., anxiety, depression)
  • Neuro-cognitive illness (e.g., dementia, multiple sclerosis, Parkinson’s)
  • Autism spectrum disorders
  • Attention deficit/hyperactivity disorders (ADHD)
  • Sleep disturbance

Additionally, functional gut disorders (e.g., reflux, nausea, vomiting, pain, constipation) and GI disease (e.g., IBS, Crohn’s, ulcerative colitis) often present with psychological conditions associated with the microbiome.

Risk Factors for GBA Disruption

Do you think you might have GBA disruption? Check out the following risk factors to affirm your suspicion.

  • Antibiotic use (maternally or during infancy)
  • Antidepressants (which may have antimicrobial impact)
  • Chronic stress (which disrupts your intestinal barrier integrity and the composition of your microbiome)
  • Early life stress (which affects your microbiome development and HPA axis)
  • Environmental toxins and exposures
  • Medications
  • Poor diet

Therapeutic Options

Good news! There are ways to improve your GBA!

Psychobiotics are now being used to treat GI illness. Psychobiotics are probiotics that, when consumed in therapeutic amounts, have a positive impact on mentalhealth.

Similarly, prebiotics (which support the growth of specific commensal bacteria with psychophysiological effects) are also included in the definition of psychobiotics.

Let me know in the chat if this is helpful (and other topics you’d like to hear about!).

Posts by Category

Free Guide to Improve Digestive Health Today!

Coconut and coconut oil

Save 15% on Pharmaceutical Grade Supplements!

Supplement pills

Recent Posts

The Biggest Mistake People Make When Solving SIBO

The Biggest Mistake People Make When Solving SIBO

There is a tendency to treat small intestine bacterial overgrowth (SIBO) like an infection. After all, it's referring to bacterial overgrowth, right? Wrong. SIBO is not an infection SIBO is not an infection like bronchitis or a UTI. Rather, it's a symptom of digestive...

Easy technique to feel less overwhelmed and accomplish more

Easy technique to feel less overwhelmed and accomplish more

Do you ever get overwhelmed by everything you have or want to accomplish in the next week? If so, here's a technique from a podcast I listened to yesterday that you may find helpful. 1. Write down everything you could do in the next week For example, ship the package,...

Pin It on Pinterest

Share This