Understanding the Gut-Brain Axis:

The gut-brain axis is a bidirectional communication system that involves the complex interplay between the central nervous system and the enteric nervous system, which is responsible for regulating the function of the gastrointestinal tract. This connection is facilitated by a network of neurons, hormones, and neurotransmitters that allows constant communication between the gut and the brain. 

The vagus nerve is a major player here, as it is the main pathway connecting the brain to the gut. Specialized cells in the lining of the intestinal wall called neuropod cells are important as well, as they communicate with the vagus within seconds of us eating something or sensing bacteria or pathogens (Kaelberer et al, 2018). The microbiome cannot be underestimated, as these bacteria produce neurotransmitters and short-chain fatty acids that stimulate the nervous system. Manipulating the microbiome can have wide reaching effects on mood, disease risk, and more. Neuroendocrine signaling occurs when bacteria in the gut trigger enteroendocrine cells in the lining of the intestinal wall to release neuropeptides like cholecystokinin which is a well-studied satiety hormone (Hirokazu et al, 2018)

Now remember that I said bidirectional, so let’s dig a little deeper on how the impact goes both ways.  

 Cognitive Symptoms that are Influenced by the Gut:

Mood and Emotions: The gut is often referred to as the “second brain” due to the significant amount of neurotransmitters, including serotonin and dopamine, produced in the digestive system. These neurotransmitters play a crucial role in regulating mood, emotions, and overall mental well-being.

Stress and Anxiety: Certain bacteria that make up our microbiome put us at higher risk of experiencing anxiety, while other strains seem to help us with our stress response. Chronic stress can disrupt the balance of gut microbiota, leading to gastrointestinal issues such as irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD) and creating a vicious cycle. 

Brain fog, Fatigue and the Immune System: Poor digestive health can result in chronic inflammation in the body, and the brain can become inflamed too! Memory loss, brain fog and fatigue can result. Food sensitivities can develop, and over time, even autoimmunity as the immune system is overactivated. The gut microbiota plays a vital role in modulating immune response as well.

Digestive Symptoms that are Influenced by the Brain:

Gut Motility: Stress, anxiety, and other mental health disorders can influence gut motility, either speeding it up or slowing it down. One example is when we are stressed and we can’t “rest and digest”. Our parasympathetic can’t engage properly. So food moves slowly, sitting in our stomach and causing bloating and constipation.

Poor food Choices: Emotional states can influence food choices, often leading to unhealthy eating habits. Comfort foods high in sugar, fat, and processed ingredients can negatively impact gut health and exacerbate symptoms of digestive disorders. But eating them releases feel-good chemicals that reward us in the short term. Conversely, a nutrient dense, high variety and personally tailored diet can help our brain and our gut thrive.

Gut Permeability: Chronic stress and anxiety can worsen gut permeability, often referred to as “leaky gut.” This condition allows harmful substances and bacteria to enter the bloodstream, triggering immune responses and inflammation.

5 Action Steps for a Healthy Brain-Gut Connection

1. Smart Diet Design: Opt for a diet rich in vegetables, fruits, clean meats and fish and gluten free whole grains to support a healthy gut microbiome. These foods provide needed polyphenols, fiber and fatty acids for the gut and brain. Probiotic-rich foods like yogurt, kefir, and fermented vegetables can also promote gut health. And don’t get in a rut – diet diversity is imperative for a truly healthy microbiome. Eat the rainbow! 
2. Vagal Tone: Gargling, singing and deep breathing exercises are great places to start here. These activities stimulate the vagus and help our nervous system stay regulated and the lines of communication open.
3. Stress Management: Engage in stress-reducing activities such as exercise, meditation, deep breathing, or yoga to minimize the impact of stress on the gut-brain connection.
4. Adequate Sleep: Prioritize good sleep hygiene to promote overall well-being. It is nearly impossible to truly heal your brain or your gut without good sleep. 
5. Professional Help: If your digestive issues are persistent, consider addressing your mental health with a professional. And if you’ve been seeing a therapist, but you’ve plateaued on progress, consider looking at your gut health as an adjunct to therapy.

The brain-gut connection underscores the significance of a holistic approach to health, considering the inseparable relationship between the gut and the brain. By nurturing our digestive health, we can positively impact our mental well-being and vice versa. Understanding this intricate connection empowers us to make informed lifestyle choices that support both our gut and our mind, ultimately leading to a happier and healthier life.

Hirokazu, F., Xu, X., & Miwa, H. (2018). Role of Gut Microbiota-Gut Hormone Axis in the Pathophysiology of Functional Gastrointestinal Disorders. Journal of Neurogastroenterology and Motility, 24(3), 367–386. https://doi.org/10.5056/jnm18071

Kaelberer, M., Buchanan, K., Klein, M., Barth, B., Montoya, M., & Shen, X. (2018). A Gut-Brain Neural Circuit for Nutrient Sensory Transduction. Science. https://doi.org/10.1126/science.aat5236