The Gut-Brain Axis: How Our Brains and Our Bugs are Connected
JULY 2023 | Dr. Ashley Southern
Trust your gut. Go with your gut. What does your gut tell you?
These are all expressions you’ve probably heard countless times that have left you wondering, just how much does my stomach know?
As it turns out, a lot.
Research has looked extensively into the connection between our stomachs and our brains, and evidence shows there is a direct correlation between them called the gut-brain axis.
What is the Gut-Brain Axis?
The gut-brain axis is the communicative network that connects your brain both physically and biochemically to your digestive system. This network consists of 500 million neurons that link your gut to your brain via a complex roadmap of nerves that runs through the nervous system. The biggest nerve that connects the brain and stomach is the vagus nerve, the main nerve of the parasympathetic nervous system (our “rest and digest” system). The vagus nerve impacts digestion, heart rate, and immune function, and plays a vital role in the way factors like stress, diet, and emotions can influence those systems.
The gut-brain axis also consists of a series of chemicals called neurotransmitters. Neurotransmitters act like tiny chemical messengers that send signals throughout the body, and control everything from vital functions to feelings and emotions. Research into the gut-brain connection has revealed that several crucial neurotransmitters that affect our brains are produced in our gastrointestinal (GI) tracts. Large amounts of serotonin, the chemical that controls happiness, are produced by the gut bugs living in our microbiome. GABA, another neurotransmitter that controls fear and anxiety, is also produced in our gut. Hence, when you have that deep, intuitive “in the pit of your stomach” feeling, it could very well be your gut bugs at work.
How Does the Gut-Brain Axis Impact Health?
Gut bacteria health plays a crucial role in our body’s overall functionality and well-being. Our gut microbiome consists of trillions of microorganisms and bacteria that live in our GI tract. These microbes, or gut bugs, contribute to vital processes like digestion, detoxification, nutrient absorption, neurosignalling, and immune system regulation. In a well-functioning and homeostatic system, there is a balance between the beneficial and harmful bugs. However, overgrowths in the bad bugs can occur, which can have a massive impact on our overall health. Research shows imbalances in the microbiome disrupts neurosignalling and increases inflammation throughout the digestive tract. This disrupts the gut barrier function and allows for harmful bacteria and toxins to penetrate the intestinal wall and enter our system. As levels of these bad bugs increases, the imbalanced gut microbiota causes an increase of inflammation in the area, leading to a vicious self-perpetuating cycle of gut dysbiosis (an imbalance in gut bacteria) and chronic inflammation.
Impact of Inflammation on our Gut Health
Inflammation caused by dysbiosis has been highly associated with causing and exasperating several digestive conditions, including colitis, irritable bowel syndrome (IBS), small intestinal bacterial overgrowth (SIBO), and Crohn’s disease.
Colitis, an inflammatory bowel disease characterized by chronic inflammation in the colon, has been linked to dysbiosis. Research shows that people with colitis have altered microbiome compositions due to increased levels of harmful bacteria. This imbalance in the gut microbiome can contribute to the inflammation associated with colitis.
IBS, a functional gastrointestinal condition known to cause abdominal pain, bloating, gas, and disrupted bowel movements, has been linked to increased levels of inflammation due to an overgrowth of Gram negative bugs in the bowel.
SIBO, a condition characterized by an overgrowth in bacteria throughout the small intestine, can cause symptoms like bloating, abdominal pain, diarrhea, and malnutrition. This overgrowth can cause inflammation throughout the small intestine, which can worsen symptoms.
Crohn’s disease, a chronic inflammatory condition that affects the digestive tact, has been associated with dysbiosis and overgrowths in harmful bacteria. These imbalances have been seen to trigger dysfunctional immune responses, resulting in chronic inflammation throughout the intestinal lining.
Gut Health and Stress
Research shows that stress and emotions heavily influence our gut health. The brain-gut axis acts like a direct phone line connecting our brains to our guts via the central nervous system. This means that the same emotional and stress signals that impact our brains can equally impact our gut function.
Chronic stress has been seen to alter the composition of the gut microbiome in several ways. GI tracts of those who experience chronic stress are seen to have overgrowths of harmful bacteria, increased intestinal permeability, and increased inflammation.
Anxiety and depression have also been associated with disrupted gut motility and impaired immune function.
The vagus nerve plays a significant role in the connection between emotions and the gut-brain axis. Studies show that people with Crohn’s disease or IBS often have decreased function of the vagus nerve (Pellissier S, 2014). This could result in decreased function of the parasympathetic nervous system, which could impact the body’s ability to respond to, react, and recalibrate from emotional or stressful situations.
Other Factors That Impact our Gut Bugs
Lifestyle factors like diet, exercise, and sleep can also influence gut bacteria and health.
Diets rich in processed foods that are high in unhealthy fats can increase the production of lipopolysaccharides, a type of Gram-negative bug highly associated with causing inflammation. Diets rich in fiber and anti-inflammatory, nutrient-dense foods can help promote biodiversity within the microbiome and encourage production of the good bacteria our bodies need.
Inadequate sleep can disrupt the brain-gut axis and lead to dysbiosis. Not getting enough sleep can also impair immune function and increase susceptibility to gastrointestinal disorders. Ensuring that you get sufficient sleep and integrating plenty of rest in your schedule can help improve your body’s functionality.
Regular exercise has been seen to promote microbiome diversity and improve gut function and motility. It’s also a great way to release stress, boost your mood, and increase energy, all of which can do wonders for improving your overall health.
What You Can Do to Restore the Gut-Brain Connection
There are several naturopathic treatments that can help restore bug balance in the digestive system, recalibrate the brain, and reestablish a healthy, functional gut-brain axis.
Managing stress is the most important thing you can do for your health. Practises like meditation and mindfulness are a great way to promote relaxation and can help balance the nervous system. An effective way to identify and mitigate any stressful triggers in life, meditation has been seen to reduce inflammation caused by chronic stress, help modulate gut bacteria, and can help to improve gastrointestinal symptoms.
Other techniques that help manage stress, including somatic breathwork and deep-breathing exercises, yoga, and tai chi, can help lower stress levels and promote digestive function. Regularly incorporating these activities into your life, or taking the time to find out what works best for you to help combat stress in your life can make a huge impact on your digestive, mental, and overall health.
The gut-brain axis and the health of gut bacteria can play a crucial role in the development and management of many gastrointestinal conditions including colitis, IBS, SIBO, and Crohn’s disease. Stress, emotions, and lifestyle factors can significantly influence gut health, exacerbate symptoms, and contribute to the onset of these conditions. Integrating naturopathic techniques into your life, such as an anti-inflammatory diet, stress management, and mind-body practices like meditation, can offer an effective approach to improving your health and quality of life.
Pellissier S, D. C. (2014). Relationship between vagal tone, cortisol, TNF-alpha, epinephrine and negative affects in Crohn’s disease and irritable bowel syndrome. Retrieved from National Library of Medicine: https://pubmed.ncbi.nlm.nih.gov/25207649/