There is a two-way communication system between the gut and brain called the gut-brain connection, or axis. It involves a complex network of nerves and biochemicals.

Experts now recognize the gut-brain connection, which has reshaped their understanding of neurological and digestive health. This bidirectional communication system establishes that the gut is not just an organ for digestion — instead, it is pivotal in influencing mental health.

The gut is sensitive to emotion, responding when a person feels anxious, sad, or excited.

For example, some individuals might feel a knot in their stomach when nervous or may face digestive upset during times of stress. Some research suggests that the brain can affect gut health, and the gut may affect brain health.

This article explores the gut-brain connection and how a person can improve it.

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Photography by Lumina/Stocksy United

The gut-brain axis is the bidirectional communication system between the digestive tract and the brain. The connection encompasses:

  • Neural pathways: The central nervous system comprises the brain and spinal cord. It interacts continuously with the enteric nervous system — a dense network of neurons lining the gastrointestinal tract. This “second brain” in the gut operates autonomously but converses continuously with the brain. The vagus nerve is one of the longest nerves connecting the gut and brain, and it sends signals in both directions.
  • Neurotransmitters: The gut produces a significant amount of neurotransmitters. These are chemicals responsible for transmitting messages within the brain. For example, it produces over 95% of the body’s serotonin, a neurotransmitter that regulates mood, appetite, and sleep.
  • Immune system components: The gut plays a vital role in immune function. Its lining is a protective barrier, and its immune cells communicate with the brain, potentially affecting mood and behavior.
  • Gut microbiota: The trillions of bacteria, viruses, and fungi that reside in the gut are collectively known as the gut microbiota. They have an active role in the gut-brain connection. These microorganisms produce various metabolites and bioactive compounds that can cross the gut barrier, travel to the brain, and influence neurological function.

The gut-brain connection influences various facets of health, from mental well-being to immune response. Disturbances within the gut can mirror disruptions in mental health.

For example, experts link an imbalanced gut microbiota to mood disorders such as depression and anxiety. This highlights the gut’s role as a potential contributor to and, in some cases, predictor of certain neurological conditions.

An imbalanced gut-brain axis can also produce digestive issues.

Disruptions in this communication pathway may lead to or exacerbate conditions such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and food sensitivities.

Furthermore, a substantial portion of the body’s immune cells reside in the gut, and their interactions can influence both local gut health and broader systemic responses. This can affect inflammatory processes, which experts have linked to various conditions, such as autoimmune diseases and neurodegenerative disorders.

Doctors refer to symptoms arising from gut-brain connection issues as DGBIs, or disorders of the gut-brain interaction. Some may also use the older term “functional GI diseases.”

These conditions include gastroesophageal reflux disease (GERD), IBS, and gastroparesis.

If someone has gut-brain dysfunction, they may experience the following symptoms:

  • abdominal pain
  • a feeling that something is stuck in the throat
  • bloating
  • constipation
  • diarrhea
  • incontinence
  • indigestion
  • regurgitation

Diet directly affects the composition and function of the gut microbiota. Increasing fiber intake with whole grains, fruits, and vegetables promotes the growth of beneficial bacteria. Limiting processed foods and sugars can discourage the growth of less beneficial or potentially harmful bacteria.

A person could also consider taking probiotic supplements. These live bacteria can help balance the gut’s bacterial community, replenishing and maintaining levels of beneficial bacteria.

Research suggests that probiotics may improve mental health symptoms of stress, anxiety, and depression.

A small 2017 study of 44 people with irritable bowel syndrome and anxiety or depression found that taking a specific probiotic for 6 weeks significantly improved their symptoms.

In addition to probiotics, prebiotics play a vital role. These are nondigestible food components that nourish the beneficial bacteria.

An older 2014 study found that taking a prebiotic called galactooligosaccharides for 3 weeks significantly reduced levels of cortisol, a stress hormone.

Fermented foods such as yogurt, kefir, sauerkraut, and kimchi are natural sources of probiotics and prebiotics. Incorporating them into a balanced diet can further support a healthy gut microbiome.

For individuals looking to improve their understanding of the gut-brain connection, here are questions to ask a doctor:

  • How does the gut-brain connection affect overall health?
  • What are the most common signs of a disrupted gut-brain connection?
  • Are problems with the gut-brain axis causing my symptoms?
  • How do lifestyle factors, such as stress or sleep, influence the gut-brain axis?
  • Are there specific foods or diets to support a healthy gut-brain connection?
  • How do my medications affect the gut microbiota and the gut-brain connection?
  • Should I consider taking probiotics or prebiotics? If so, which ones are most beneficial?
  • Are there any tests or evaluations to assess the health of my gut-brain connection?
  • How often should I have check-ups or follow-ups related to gut-brain health?
  • Are there other specialists or healthcare professionals you recommend I consult regarding my gut and brain health?

Communication between the gut and the brain is called the gut-brain connection. It comprises nerves, neurotransmitters, gut microbiota, and immune components.

The gut-brain connection plays a pivotal role in mental and digestive health, and by altering gut bacteria, it may be possible to improve brain health. Symptoms of gut-brain connection dysfunction may include digestive upsets, abdominal pain, and indigestion.

Eating a balanced diet and including probiotics and prebiotics can support the gut-brain connection.