Department of Medicine School of Medicine

How the Brain Influences Gut Health and Function

By Tayler Shaw | October 14, 2024

The connection between the brain and gut is deeper than many realize, impacting our digestive health in profound ways. Jennifer Christie, MD, Head of the Division of Gastroenterology and Hepatology at the University of Colorado, explains how the brain-gut relationship affects gastrointestinal disorders and shares tips for supporting overall health.


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The Gut-Brain Connection: A Bidirectional Relationship

The phrase "butterflies in your stomach" often refers to the nervous sensations we feel in our gut when anxious, but this physical sensation points to the deeper and more complex relationship between the brain and digestive system. According to Dr. Jennifer Christie, this connection is not only real but also incredibly influential in how our bodies experience gut health.

Dr. Christie explains that there are more than 20 different functional bowel disorders, which are rooted in what’s called the "gut-brain axis." These disorders include conditions like functional bloating, constipation, diarrhea, and irritable bowel syndrome (IBS), which affects an estimated 25 to 45 million people in the U.S. alone.


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The Complexity of Diagnosing Functional Bowel Disorders

One of the key challenges in diagnosing functional bowel disorders is that symptoms often don’t show up in tests. "These disorders are tricky because they don’t have clear biomarkers like inflammation or infection, and patients often experience chronic or recurrent symptoms that don’t match with a conventional diagnosis," Dr. Christie explains. As a result, many patients with these conditions are left frustrated when their tests show no abnormalities despite ongoing symptoms.

“The brain and gut communicate constantly, sending signals that can sometimes become misaligned, leading to symptoms like bloating, pain, or irregular bowel movements,” Dr. Christie notes. While researchers have yet to fully understand the underlying mechanisms, it’s clear that the brain's signals play a significant role in many gastrointestinal disorders.


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Exploring the Enteric Nervous System

At the heart of this gut-brain connection is the enteric nervous system (ENS), a complex network of neurons embedded within the gastrointestinal tract. This system, which works closely with the central nervous system (CNS), is responsible for managing the motor functions and sensations we experience in our gut.

One of the key players in this communication is the vagus nerve, which runs from the brain to the stomach and acts as a pathway for the bi-directional exchange of information between the gut and the brain. “The ENS is embedded in the autonomic nervous system, and it governs sensations like hunger, fullness, and bloating,” explains Dr. Christie.

Neurotransmitters like serotonin, which is often associated with mood regulation, also play an essential role in gut function. “Most of the body's serotonin is actually produced in the gut. It helps regulate peristalsis—the contractions that move food through the digestive system—and also impacts sensations like bloating or the feeling of fullness,” Dr. Christie adds.


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Serotonin and the Gut Microbiome

Serotonin’s role in the gut extends beyond just regulating motility. The hormone is involved in managing how the gut "feels" and functions, including our perception of sensations like hunger or bloating. As such, serotonin is a target for many medications designed to treat conditions like IBS, especially when constipation or diarrhea is present.

However, serotonin is just one part of a more intricate picture. Functional bowel disorders are influenced by a range of factors, including genetics, environmental exposures, and, importantly, the gut microbiome—the community of microorganisms (bacteria, viruses, fungi) living in our digestive system. These microorganisms produce chemicals and hormones that communicate with both the brain and the gut, creating a continuous feedback loop.

Researchers, including those at the University of Colorado, are studying how the microbiome influences gut health and how imbalances may contribute to disorders like IBS. Dr. Christie notes that understanding the gut microbiome’s role in functional bowel disorders is still an ongoing area of research. "We’re beginning to ask questions about whether people are genetically predisposed to a certain microbiome that could increase their risk for these symptoms."


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Strategies for Supporting Brain and Gut Health

While much of the science behind gut-brain interactions is still unfolding, there are several steps individuals can take to support their overall gut and brain health. Dr. Christie emphasizes the importance of listening to one’s body, especially when it comes to identifying triggers like certain foods or stressful situations that can provoke symptoms.

In addition to dietary awareness, managing stress, regular exercise, and getting adequate sleep are crucial for maintaining a healthy gut. "Day-to-day stress can have a profound impact on our gut function, contributing to symptoms like bloating or diarrhea. Finding ways to manage stress—whether through mindfulness techniques, relaxation practices, or regular physical activity—can help regulate how the brain interacts with the gut," Dr. Christie advises.


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The Role of Behavioral Therapies

For those with functional bowel disorders, behavioral therapies can also be effective in helping manage symptoms. Dr. Christie explains that treatment approaches like biofeedback, cognitive behavioral therapy (CBT), and gut-directed hypnotherapy aim to reframe how the body responds to certain triggers. These therapies help patients alter their thoughts and emotional responses so that physical symptoms, like pain or nausea, are reduced.

"We see good outcomes with psychological therapies for our patients," Dr. Christie adds. "The idea is to retrain the body to have a more controlled response to stress and other external triggers that may be contributing to gut symptoms."


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Looking Ahead: Future Research and Advancements

While we know more than ever about the connection between the brain and gut, much is still to be discovered. Researchers are working to identify which individuals are at risk for functional bowel disorders and to develop more effective treatments. Advances in microbiome research, in particular, could lead to breakthroughs in how we prevent or treat these conditions in the future.

"We’re just scratching the surface," Dr. Christie says. "Here at the University of Colorado, we’re conducting ongoing studies to explore the many factors that influence gut health, and we hope that these efforts will lead to better treatments and a deeper understanding of the brain-gut axis."


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Takeaway: How to Support Your Gut Health Today

If you’re experiencing symptoms like chronic bloating, constipation, or unexplained gastrointestinal discomfort, Dr. Christie encourages early consultation with a healthcare provider. "The sooner you start exploring potential triggers and treatment options, the better. By combining lifestyle changes, therapies, and professional guidance, it’s possible to improve both brain and gut health."

Key strategies for supporting your health include:

Listen to Your Body: Identify and avoid foods or behaviors that trigger symptoms.

Exercise Regularly: Physical activity can reduce stress and improve gut function.

Manage Stress: Practice mindfulness or other stress-reduction techniques to help your gut.

Get Enough Sleep: Prioritize rest to maintain optimal gut function.


With continued research and growing awareness, supporting both brain and gut health will be an important part of managing and preventing gastrointestinal issues.


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By understanding and nurturing the gut-brain connection, individuals can take steps toward improving both mental and physical health for a balanced and functional life.