A Healthy Gut Can Lead to a Happy Mind
Most of us have experienced butterflies in our stomach when we’re nervous, or a gut feeling that confirms our intuition. These sensations emanating from your body are one of the signs that suggest that your brain and gut are connected. Not only is there a system of communication known as the gut-brain axis, but this system sends all kinds of signals throughout your body linking digestion, mood, thoughts, and overall health. Studies are now showing that our brain affects our gut health and our gut affects our brain health. When the gut ecosystem is out of balance, it can significantly affect your mood, pain tolerance, cognition, behavior, and overall mental and physical wellbeing.[i] Depression and anxiety may be a result of more than chemical imbalances of the brain or related to significant life events, adding the gut microbiome as a relevant piece of the mental health picture and an opportunity to explore mood disorders from the inside out.
What is the Gut-Brain Axis and the Second-Brain?
The gut-brain axis refers to the physical and chemical connections between your gut and brain. The gut microbiome is made up of the trillions of microorganisms and their genetic material that lives in your intestinal tract. These microorganisms, mainly comprising bacteria, are involved in functions critical to your health and wellbeing, such as digestion, metabolism, immune function, and brain health. Our gut microbiome begins to develop in very early life and is influenced by genetics, delivery method, age, stress, illness, environment, medication use, and diet. As we are all unique individuals, our gut microbiomes will also vary in diversity. Similar to a bacterial fingerprint, it is specific to you, yet constantly changing.[ii]
The microbes that live in your gut can actually influence your feelings and behaviors. These bacteria and microorganisms directly correspond with your head along the gut-brain axis—also known as the vagus nerve, one of the longest nerves in the body, that sends signals between the gut and the brain. Your enteric nervous system (ENS) is a large network of neurons in your gastrointestinal tract that communicates with your central nervous system via the vagus nerve. The vagus nerve represents the main component of the parasympathetic nervous system, which oversees a vast array of crucial bodily functions, including control of mood, immune response, digestion, and heart rate. In short, it is a bidirectional information highway, sending messages between the gut and brain within milliseconds.[iii]
The ENS has been referred to as the “second brain” as it can function independently of the central nervous system, which most of the other neural networks in the human body cannot do. It does more than just handle digestion; it helps determine our mental state, has power over our emotions, and plays a key role in certain diseases throughout the body. “Your gut has capabilities that surpass all your other organs, and even rival your brain,” says ENS specialist Dr. Emeran Mayer. “It is even thought that the second brain has probably been around much longer than the brain you’re currently using to read and understand these words.” The brain in our gut is not capable of thought as we know it, yet it communicates with the mid brain, playing a critical role in mental and emotional well-being.
Not only does the gut-brain axis communicate through the nervous system, but also through hormones, and the immune system. Gut microbes play an important role in your immune system and inflammation by controlling and regulating what is passed into the body and what is excreted. At least 70 percent of our immune system is aimed at the gut to expel and kill foreign invaders. When our immune system is stressed, it contributes to inflammation of the GI tract, in turn leading to the development of symptoms of disease that occur not only throughout your body, but also in your brain. Researchers are speculating that this is caused by disruption to the normal, healthful balance of bacteria in the microbiome as your gut modulates your stress response. When our gut is out of balance, our brain also becomes unsettled, showing how stress affects the diversity of the microbiome and can lead to depression and anxiety.[iv]
How is Gut Health Linked to Mental Health?
We often give credit or place blame on the brain for our moods and emotions, when in fact, a big part of our feelings is influenced by the nerves in our gut microbiome. The gut is critical for cognitive function and mental health. There are approximately 100 billion neurons—the cells found in your brain and central nervous system that tell your body how to behave—in the human brain. Interestingly, your gut contains 500 million neurons, which are connected to your brain through nerves in your nervous system.[v]
Your gut and brain are also connected through chemicals called neurotransmitters that influence your feelings and emotions. We have more serotonin in our stomachs than in our brains, yet this fact is often overlooked when working to restore emotional balance. Over 90% of our body’s serotonin (your “happy” neurotransmitter) is made and regulated by your gut microbiome[vi], and somehow this significant data easily takes a backseat in the mental health field. Practitioners primarily prescribe psychotropic medications or focus on cognitive interventions when also looking at our internal health is necessary to provide comprehensive care and support.
Several studies are being conducted that link alterations in the microbiome with depression, anxiety, bipolar disorder, autism, ADD/ADHD, irritable bowel syndrome, and other psychological or neuropsychological disorders.[vii] A number of studies have also shown that people with various psychological disorders have different species of bacteria in their guts, compared to healthy people.[viii] Furthermore, when the bacteria in the GI tract is altered and balanced (through probiotics and other means), a reduction of depression and anxiety can occur. Beneficial gut bacteria can support a positive mood.[ix] Individuals who struggle with anxiety and depression are more likely to also experience gastrointestinal symptoms. All too often, these cognitive and digestive symptoms are thought to be independent of one another, ignoring the important link between mental and physical health.
What You Can Do
This “crosstalk” in communication between the brain and digestive system is opening up new ways to think about diseases. When we recognize how our emotions are influenced by the nerves in our gut, we can utilize a more holistic approach to health that acknowledges underlying emotional factors as well as environmental and physiological components. We can also take a broader look at ways to calm the nervous system including the vagus nerve’s role in helping your body return to a state of emotional balance and resilience. Some research is even showing that vagal stimulation, leading to a higher vagal tone, can reduce stress, increase mood and even rewire various trauma responses. Restoring homeostasis involves a mind-body approach that views your gut as a potential and significant pathway to health.
I have personally experienced ways in which prolonged antibiotic use has led to dysbiosis and microbial imbalance. Taking time to restore my health from the inside out continues to be a significant component of my recovery from a neurological condition. Understanding and witnessing the link between my gut and brain further exemplifies ways in which different systems of the body are interconnected and cannot be completely understood in isolation. This connection can be seen in ways that stress and strong emotions contribute to or worsen a variety of GI conditions and symptoms. Additionally, prolonged GI issues can intensify stress and anxiety. The gut needs to heal before we can reset healthy communication with the mind. Treating the whole person, not just the symptoms, is an effective bottom-up approach to mood disorders.
Therapy and, in some cases, antidepressant or anti-anxiety medications can be important pieces of treatment. But if underlying imbalances in the gut microbiome are at the root, it is harder to mentally heal until they are addressed. This is a process of first removing harmful bacteria, resetting digestion, rebuilding and rebalancing healthy flora, and rethinking and challenging our perceptions. To support overall microbiome functioning, it is important to maintain a strong balance in favor of beneficial bacteria in your digestive tract. The right foods have the ability to improve your mood. This includes eating a wide variety of high-fiber, fermented foods, Omega-3 fatty acids, probiotics, prebiotics, and other polyphenol-rich foods. Limiting your intake of artificial sweeteners and taking antibiotics only when necessary can also help.[x] As our microbiomes vary significantly, it is beneficial to consult with a clinician that can assess individual ways to support your unique gut and lifestyle. More importantly, it’s beneficial to be aware of the gut-brain axis and its significant role in influencing immunity, inflammation, and mood. When your gut is speaking to you, it is worth slowing down and tuning in to its messages, as your second brain is wiser than we may have previously realized. A healthy gut is one of the paths to a happy mind.
[i] https://www.ncbi.nlm.nih.gov/pubmed/24997043
[ii] https://foodandmoodcentre.com.au/2016/07/what-is-the-gut-microbiome/
[iii] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5859128/
[iv] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1760754/
[v] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2776484/
[vi] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4393509/
[vii] https://www.psycom.net/the-gut-brain-connection
[viii] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4879184/
[ix] https://www.sciencedirect.com/science/article/abs/pii/S0889159116305578?via%3Dihub