It’s increasingly becoming common knowledge that our gut microbiome influences digestion, allergies, and our metabolism. We are also discovering how it influences anxiety & depression. After all, 90% of serotonin is made in our digestive tract.
There is a huge and ever-growing body of evidence connecting the health of the gut to the health of the brain. If you have inflammation, parasites, fungal overgrowth or dysbiosis in your gut, that is going to produce an inflammatory response that in turn affects the brain and can cause inflammation and a whole bunch of other problems in the brain. While unfortunately not a lot of primary care doctors or even psychologists and psychiatrists consider this connection, it is now well established in scientific literature.
We basically have two nervous systems: the central nervous system-found in the brain and spinal cord, and the intrinsic nervous system of our gastrointestinal tract (commonly referred to as the enteric nervous system). Both of these are formed from identical tissue during fetal development. Both nervous systems are connected via the Vegas nerve and communicate in both directions. This means that the health status of our gut is going to affect our brain, and our mental health in turn affects our gut.
There was a study in 2015 by Stephen Collins where they transferred gut bacteria from anxious humans into mice who then became anxious. There was another interesting study in 2013 published by Mayer showing how eating yoghurt for two weeks made positive changes in brain activity.our gut bacteria produce neurotransmitters (like serotonin, dopamine, & GABA), and certain microbes are able to activate the Vegas nerve; our main line of communication between the gut and the brain. Our gut is also intertwined with our immune system (2/3 of our immune system being in our gut) which in itself affects mood and behavior. In fact, the most current theory on what causes depression is inflammation, which supresses the activity of the frontal cortex. There is also tons of research linking gut disturbances with Parkinson’s, autism, Alzheimer’s, ADHD, sensory processing disorders, OCD, and even schizophrenia and psychosis.
Not to mention the stress of everyday life is constantly activating our HPA Axis (our hypothalamic-pituitary-adrenal axis which governs our stress tolerance as well as our response to stress). When these systems are chronically activated (which they weren’t designed to be) it leads to changes in the output of stress hormones like DHEA and cortisol which in turn affects the production of many other hormones and neurotransmitters in the body. What adds to this is even if you don’t necessarily feel stressed – inflammation, blood sugar dysregulation and circadian disruption (too much exposure to artificial light at night and not enough exposure to natural light during the day) are physiological stressors that have similar effects as mental stress.
We must be mindful to reduce the stress we are able to control, and manage the stress that is out of our control by implementing stress reducing techniques like yoga, meditation, and deep relaxation in whatever form you personally connect with. On a nutritional level, it is highly beneficial to keep a food journal, I guarantee you will begin to notice patterns of what works for you and what doesn’t. We are all biochemically unique, and what one person may thrive on, another could be aggravated by. Food journals bring awareness to the matter and are a great first step to a healthier relationship to your food.