The Gut-Brain Connection

Many studies have shown that there is communication between the gut and the brain, called the gut-brain axis.  The systems are bidirectional, meaning the gut influences the brain and the brain influences the gut.  One way the 2 systems communicate is via the vagus nerve, which connects the central nervous system and the enteric nervous system (involved with gut function) and therefore delivers information from/to the brain and gut.  Additionally, serotonin, a neurotransmitter involved with mood, happiness, eating and digestion, is largely produced in the gut, and changes in gut can affect serotonin production, which can therefore affect brain function.Lastly, gut microbiota play a role in the gut-brain axis. The microbiome contains trillions microorganisms including bacteria and viruses which are involved in communication between the gut and brain, digestion, balancing hormones and boosting immunity.  The microbiome can be affected by stress, environment and food choices. Stress decreases a substance in the intestines called secretory IgA  (SIgA), which is the first line of defense in the mucous membranes of the intestinal epithelial barrier. SIgA binds to toxins, bacteria, etc so they cannot enter the body. When there is less SIgA, we have an altered balance of pathogens, which can lead to leaky gut.  As far as dietary considerations, a high fructose diet and a Western diet can lead to an overgrowth of bacteria. Further, nutrient deficiencies, especially in vitamin A, magnesium, zinc and vitamin D, can affect the intestinal barrier.The gut and brain affect each other in a cycle. Stress, diet and triggers from the environment can change our micriobiota. This leads to the break down of the gut barrier and a change in the bacteria balance, which causes leaky gut, which allows endotoxins to go into the bloodstream and cause and immune response. When the immune system is activated, cytokines are produced. These cytokines break down the blood brain barrier and change the levels of neurotransmitters.  Cytokines reduce tryptophan metabolism, which decrease serotonin production. The altered neurotransmitters change how the neurons are connected (plasticity), which results in neural, behavioral and/or mood changes.   When people feel differently, they alter their behaviors and make poor dietary and life choices. These changes translate into stress, dietary and environmental triggers and the cycle repeats.Research shows us that almost all mental health disorders have been associated with inflammation, oxidative stress and elevated level of cytokines.  To fix the brain and gut we need to reduce inflammation and toxins. Exercise is key, along with decreasing stress with mind body exercises. It is also important to avoid food allergens/sensitivities and toxins in the environment including fast foods and processed foods.  Supplements like probiotics and fish oil are key to decreasing gut inflammation and improving mood, anxiety and depression