The Gut/Brain Axis and Mental Health

Truth bomb… gut health and brain health are not two separate things… they are deeply and intricately connected!

The relationship between nutrition and mental health is mediated between an important network called the gut-brain axis. Did you know that we actually have a “second brain” In our gut? This second brain is also known as the enteric nervous system, which is comprised of a complex network of millions of nerves and chemicals that communicate with the central nervous system (Korn, 2016). This bidirectional communication takes place through the gut-brain axis. Fibers in the vagus nerve carry messages from the digestive system to the brain and back. As Lindsay Christensen states, “Signaling molecules created by gut microbes and cells of your intestine send messages to your brain along the gut-brain axis, influencing your mental and emotional functions. Signals also travel the opposite direction such that our mental and emotional states affect our gut function.” (Christensen, 2019).  Given this impressive relationship, it makes sense that the diet we eat would have an impact on our mental health. 

Our gut microbes produce chemical metabolites, including neurotransmitters such as serotonin, gamma aminobutyric acid (GABA), norepinephrine, and dopamine (Caspani, et al., 2019), as well as a number of other compounds. You read that right… neurotransmitters are actually produced in our gut! Once these compounds are created by our microbes, they either activate the fibers of the vagus nerve, or get absorbed directly in to the bloodstream where they interact with organs in the body including the brain (Caspani, et al., (2019). These metabolites can also stimulate the immune system within the gut, known as the gut-associated lymphoid tissue (GALT). The GALT consists of Peyer’s pacthes that are found in the mucosal lining of the gastrointestinal tract (Nutritional Therapy Association, 2019), which meet up with pathogens and create an immune response, and in turn chronic inflammation and mental health disturbances (Firth, et al.., 2019). 

The Impact of the Standard American Diet

I believe that we all have an innate wisdom about the foods that serve and don’t serve our bodies. The problem is that we have grown disconnected from this inner knowing. Much of this disconnect stems from the current state of our food industry, and what is known as the Standard American Diet (SAD). The SAD consists of foods that are pumped full of additives, preservatives, colorings, and flavorings. These foods are heavily refined and processed, and full of added sugars. Hormones, antibiotics, steroids, and pesticides are being used in the production of these foods. Crops are being genetically modified. Farming methods have left us with nutrient poor soil in which to grow our vegetables, so what we are eating is far less nutrient dense than the same food might have been years ago. Foods actually contain little nutrients, but are high in calories. They come in brightly colored packages, that entice us (especially kids). The list goes on. And the bottom line… these foods are making us sick! The chemical components of these food only serve to increase our hunger levels and turn off our normal satiety cues. In turn we continue to seek out nutrients, only to end up eating more of the foods that are making us ill. 

Much of the SAD contains foods that I would call hyperpalatable. By this, I mean that foods have been designed to be sweet, salty, and fatty. These flavors light up the regions of the brain related to pleasure, motivation, and reward-seeking. Neurotransmitters (most notably dopamine) and endorphins are released, and we are left wanting more (Nutritional Therapy Association, 2019). Robb Wolf, in his book “Wired to Eat” states that “stimulating dopamine centers of the brain creates a feedback loop in which one desires more of the substance or activity that elicited the good feeling” (Wolf, 2017). In essence we are addicted to these foods. 

Humans evolved to seek out these sweet, salty, and fatty foods. Eating these calorically dense foods made sense as we needed to store fuel in times of food shortages. However, over the course of a few hundred years or so, we have gone from eating whole, nutrient-dense sources of these foods to eating these chemical-ridden, hyperpalatable foods which are everywhere and not in shortage. 

Without question, the SAD leaves us deficient in crucial nutrients (such as Omega-3 fats and essential minerals). Intestinal permeability is increased (which is linked to anxiety and depression) (Stevens, et a., 2018). The SAD negatively impacts the gut microbiome, by creating an inflammatory environment. As a result, we see dysfunction in the gut-brain axis (discussed above). Research now demonstrates that a processed and refined Western Diet is highly linked to depression and anxiety (Adjibade, et al., 2019, Banta, et al., 2019). The more inflammatory the diet, the higher association there is with Schizophrenia (Jahrami, et al., 2019). The list goes on. 

If you are one of the million Americans who experiences mental health symptoms, or you have a child or family member who is in need of support, I would love to be of service. I am experienced across a wide variety of health and mental health diagnoses. Please reach out for a FREE discovery call today!

References:

• Adjibade, M., Julia, C., Allès, B., Touvier, M., Lemogne, C., Srour, B., Hercberg, S., Galan, P., Assmann, K., & Kesse-Guyot, E. (2019). Prospective association between ultra-processed food consumption and incident depressive symptoms in the French NutriNet-Santé cohort. BMC Medicine,17(78). 
• Caspani, G., Kennedy, S., Foster, J., & Swann, J., (2019). Gut microbial metabolites in depression: understanding the biochemical mechanisms. Microbial Cell, 6(10), 454-493.
• Christensen, L. (2019). Nutrition and mental health: What’t the connection?. Retrieved from
  https://chriskresser.com/nutrition-and-mental-health-whats-the-connection/
• Firth, J., Veronese, N., Cotter, J., Shivappa, N., Hebert, J., Ee, C., Smith, L., Stubbs, B., Jackson, S., & Sarris, J. (2019). What Is the Role of Dietary Inflammation in Severe Mental Illness? A Review of Observational and Experimental Findings. Front Psychiatry, 10, 350.
• Jahrami, H., Faris, M., Ghazzawi, H., Saif, Z., Habib, L., Shivappa, N., & Hebert, J. (2019). Increased Dietary Inflammatory Index Is Associated with Schizophrenia: Results of a Case–Control Study from Bahrain. Nutrients, 11(8), 1867.
• Korn, L., (2016). Nutrition essentials for mental health: A complete guide to the food-mood connection. New York, NY: W. W. Norton & Company.
• Nutritional Therapy Association (2019). Evolution of the Modern Diet. Olympia, WA: Nutritional Therapy Association, Inc. 
• Nutritional Therapy Association (2019). Immune System: Student Guide. Olympia, WA. Nutritional Therapy Association, Inc.
• Stevens, B., Goel, R., Seungbum, K., Richards, E., Holbert, R., Pepine, C., & Raizada, M. (2018). Increased human intestinal barrier permeability plasma biomarkers zonulin and FABP2 correlated with plasma LPS and altered gut microbiome in anxiety or depression. Gut, 67(8), 1555-1557.
• Wolf, R. (2017). Wired to eat. (pp. 41-42). New York, NY: Harmony Books.