The Connection Between Gut Health and Mental Health

The next time someone asks - “What’s your gut telling you?” - you might want to listen closely to the answer/to the voice inside your belly.

Why? Because the gut and brain can “talk” to each other through nerves, and there is a growing body of evidence that this bidirectional, back-and-forth communication between your digestive system and your central nervous system can have a major impact on the health of each other.

It might seem weird that your gut has the ability to influence your mental state-of-mind, but if you’ve ever felt “butterflies” or had a “nervous stomach” or gotten a “gut feeling” then you already know there’s a link.

This connection, known as the gut-brain axis, makes some scientific sense too. Research shows there are more nerve cells in your gut than anywhere else in the human body (besides the brain) and more information passes between the brain and digestive system than any other system in the body.

Exploring the Link Between Gut Health and Mental Health

The gut-brain axis refers to the two-way communication network that links the gastrointestinal (GI) system to the brain and central nervous system, and this connection has garnered significant attention in recent years.

Studies have shown that people with depression (and other mental health diagnoses) often have altered gut biomes compared to healthy individuals, and for years, scientists postulated that mental health issues came first and GI problems came next.

But new data and observational research are turning this hypothesis on its head. And now scientists believe that an unhealthy gut can actually contribute to mental health issues and not just be the effect of them.

Research has also demonstrated that probiotics – live microorganisms that can confer health benefits – can have a positive impact on mental health and has been associated with improved cognitive function and reduced depression and anxiety in some people.

The gut-brain connection involves other mechanisms besides the digestive system and nervous system and also includes the immune system, endocrine system, and hormonal pathways.

There are several key players at the heart of this gut-brain relationship:

Enteric Nervous System

The enteric nervous system describes the network of nerves that operate within the GI tract and control digestion. With hundreds of millions of neurons, it’s the most complex ‘nervous system’ outside of the brain, which has led some scientists to refer to it as a ‘second brain’.

This system is part of the autonomic nervous system, which governs the automatic/involuntary functions of your internal organs. This means, while you’re busy doing other things – sleeping, working, playing – the enteric nervous system is continuously gathering and processing information about your GI system and responding without much input from the brain.

The Vagus Nerve

The vagus nerve is a major nerve that runs from the brainstem to the abdomen, and it plays a crucial role in transmitting signals from the enteric nervous system to the brain. This nerve shares sensory information about the gut and receives motor signals from the brain, which allows it to mount a rapid response to chemical changes and the presence of food.

Gut Microbiome

Another key player in the gut-brain connection is the gut microbiome – a complex community of microorganisms, like bacteria, viruses, and fungi, that reside in the digestive tract. These microbes help produce neurotransmitters that convey messages between the gut and brain, and they actively participate in numerous physiological functions, including digestion and immune function.

There is significant overlap between people who have functional gastrointestinal disorders, like IBS (irritable bowel syndrome), and mental health problems, like anxiety, and recent studies show that the gut microbiome likely plays a role in this observation.

How Gut Health Influences Mental Health

The relationship between gut health and mental health is complicated, and researchers are just starting to better understand the connection. Here are a few of the mechanisms involved:

• Neurotransmitter Production: Many of the neurotransmitters critical for mood regulation, such as serotonin, dopamine, and gamma-aminobutyric acid (GABA), are produced in the gut. In fact, approximately 90% of the body's serotonin - a neurotransmitter associated with feelings of well-being and happiness - is produced in the gut.
• Inflammation and the Immune System: Chronic inflammation is increasingly recognized as a contributing factor to various mental health conditions, including depression and anxiety. The gut microbiome helps regulate the body's immune response, and an imbalance in gut bacteria can lead to increased inflammation, impaired brain function, and the development of mental health disorders.
• The Gut Barrier and Leaky Gut Syndrome: The gut lining serves as a barrier that prevents harmful substances, such as toxins and pathogens, from entering the bloodstream. When this barrier is compromised - a condition often referred to as "leaky gut" - it can allow these harmful substances to enter the bloodstream. This process triggers an immune response and inflammation, which can lead to cognitive decline and mental health issues.
• Stress Response and the HPA Axis: The hypothalamic-pituitary-adrenal (HPA) axis is a central part of the body's stress response system. Research suggests that the gut microbiome can influence the activity of the HPA axis and affect how the body responds to stress. Unhealthy amounts of stress can cause inflammation and impaired immunity which, in turn, can cause mental health problems.

Steps to Support Gut and Mental Health

Considering the strong connection between gut health and mental health, it pays to have a strategy for supporting and improving your brain and belly health. Experts continue to explore the best ways to nurture the gut-brain connection, but for now, their best advice involves two primary considerations: improving your diet and reducing your stress.

Improving Your Diet

• A diet rich in fiber, fruit, vegetables, and fermented food can promote a healthier gut biome. Yogurt, kefir, and kimchi contain gut-friendly probiotics while garlic, onions, and bananas have prebiotics that help feed healthy gut bacteria.
• Antioxidants and anti-inflammatory foods, which are found in whole foods, like fruits and vegetables, fight harmful free radicals and can help prevent inflammation.
• Limiting the intake of processed food, sugar, and alcohol can help too. These substances can disrupt the gut biome and cause an inflammatory response.

Reducing Stress

• Chronic stress has a major impact on gut and brain health, so finding effective ways to manage stress is crucial to maintaining a strong gut-brain connection.
• Mindfulness practices, like meditation and yoga, deep breathing exercises, regular exercise, and better sleep are all great ways to reduce stress and improve your gut and mental health.
• Try therapy. Cognitive behavioral therapy, gut-directed relaxation training, and biofeedback are all wonderful ways to reduce stress and improve gut health, mental health, and overall health and wellbeing.

The gut-brain axis is a super highway of nerves and chemical messengers that connect our digestive system and central nervous system, and this connection underscores the importance of taking a holistic approach to health and wellbeing. While science continues to explore this complex relationship, we can nurture our gut biomes with lifestyle changes, like eating a healthy diet and reducing stress levels, and improve our gut health, brain health, and overall health and wellbeing in the process.