For decades, the gut and brain were looked at as two separate entities. What we now know is that this couldn’t be further from the truth. Modern research is discovering that mood hormones play a direct role in the mechanisms of digestion (challenging the thought, are truly just ‘mood’ hormones), and even more interestingly, the microbiome. If you’ve ever had a ‘gut-wrenching’ experience or felt ‘butterflies’ when stressed, you’re likely no stranger to the influences stress can have on the way our digestive tract feels. However, have you ever stopped to think about why this happens, and how?
The Vagus Nerve The vagus nerve is one of the longest nerves in the human body, with direct communication between the medulla oblongata (part of the brain stem responsible for autonomic control) and the stomach and colon. It is argumentatively the most important regulator of our ‘rest and digest' nervous system. The vagus nerve sends signals to the muscles of the stomach, encouraging it to move food into the small intestine. It also sends information back to the brain about the state of our digestive system. What’s of great interest to modern research is the role of the vagus nerve in the treatment of mood-related disorders, such as clinical depression. There is preliminary evidence showing that vagal nerve stimulation may be an important treatment option for treatment-resistant depression, PTSD and even inflammatory bowel disease (due to the ability to reduce inflammatory cytokines) (1,2). Furthermore, research is now suggesting the role of the microbiome in benefiting mood and anxiety may come from its effects on vagal nerve tone (3). Gut microorganisms are capable of producing and delivering neuroactive substances such as serotonin and gamma-aminobutyric acid, which act on the gut-brain axis. Preclinical research in rodents suggested that certain probiotics have antidepressant and anxiolytic activities (3). The research even goes as far as to show that stress exposure directly disrupts the microbiome in a way that increases the development of immune-mediated colitis (4). Lastly, the vagus nerve may also play a role in weight gain due to its influence on the hormones that control satiety and appetite (5). Diagnosing Gut Conditions and Problems When diagnosing gut conditions, it's always important to determine whether the issues could be related to various signals being sent from the brain, or vice versus. This is why determining the underlying causes is essential rather than just treating the symptoms. For instance, you may be experiencing frequent heartburn even though you are eating regularly and avoid foods that are excessively spicy or high in acids. Upon investigation, we discovered you have been under an excessive amount of stress at work. By properly supporting stress and inherently improving vagal nerve communication of gastric emptying, your bouts of heartburn may start to subside and disappear. Gut-Brain Connection Common Symptoms The body can present with a variety of symptoms when there is something wrong with the gut-brain connection. Some of the more common symptoms may include, but are not limited to:
Decreased sex drive
Depression and/or anxiety
Excess weight gain or weight loss
Lack of energy
Increased sadness or anger
Poor memory recall
Starting bad habits (Smoking, Excessive Drinking, etc.)
Of course, there can also be numerous other underlying causes of the symptoms listed above. However, they should never be ignored. If you start to notice something is wrong, particularly with the presentation of new digestive symptoms under high states of stress (or vice versa), it’s best to see your Naturopathic Doctor to discuss ways you can support the gut-brain connection. Lastly, it’s important to remember that communication is a two-way street. While the research now concluded that IBS is not a stress-induced condition (just as many people with high-stress report IBS symptoms as those with less stress), we now know that stress can worsen your state of digestive health, and a poor state of digestive health and worsen your mental health. For more information about the gut-brain connection, or to find out what is causing your gut problems, please feel free to schedule an appointment with Dr. Courtney Homberg, Naturopathic Doctor in Toronto, by calling 647-351-7282 today! References:
Evrensel A, Ceylan ME.The Gut-Brain Axis: The Missing Link in Depression.Clin Psychopharmacol Neurosci. 2015 Dec 31;13(3):239-44.
Bonaz B, Sinniger V, Pellissier S.Vagus nerve stimulation: a new promising therapeutic tool in inflammatory bowel disease.J Intern Med. 2017 Jul;282(1):46-63.
Carabotti M, Scirocco A, Maselli MA, Severi C. The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Ann Gastroenterol. 2015 Apr-Jun;28(2):203-209.
Gao X, Cao Q, Cheng Y, Zhao D, Wang Z, Yang H, Wu Q, You L, Wang Y, Lin Y, Li X, Wang Y, Bian JS, Sun D, Kong L, Birnbaumer L, Yang Y. Chronic stress promotes colitis by disturbing the gut microbiota and triggering immune system response. Proc Natl Acad Sci U S A. 2018 Mar 27;115(13):E2960-E2969.
Hagemann D, Meier JJ, Gallwitz B, Schmidt WE. Appetite regulation by ghrelin - a novel neuro-endocrine gastric peptide hormone in the gut-brain-axis.Z Gastroenterol. 2003 Sep;41(9):929-36.