The Surprising Connection Between Your Gut & Your Brain: Our Naturopathic Doctor Explains
Gut Feelings – The Connection
Have you ever felt ‘butterflies’ in your stomach? On making a difficult decision, have you been told to “go with your gut”? Have you ever been nervous to the point of feeling nauseous? Well, as it turns out, it is no coincidence that all of these expressions refer to a feeling in our gut, as a result of our mental emotional state. The gut-brain connection is not merely metaphorical.
The health of our gut has become a hot topic over recent years. Now, the science shows that there is a strong connection between the gut and the brain. Our brain is connected to the gut through the enteric nervous system (ENS). The ENS is made up of hundreds of millions of nerve cells that are found in the muscular walls from the esophagus down to the anus (1). It functions to control the movement of food through the gastrointestinal (GI) tract, the release of digestive enzymes, the amount of blood flow to assist in nutrient absorption, and our bowel movements (2). Although communication is maintained, the ENS is so complex that it can operate on its own without constant input from the central nervous system, the brain (3). Imagine if we had to actively think about digestion, we would have no brain power to complete anything else in our day! This is the reason we commonly refer to the ENS as our “second brain”.
The Second Brain & the Microbiome
The rate at which food is being moved and how much mucus is lining the gut, controlled by the ENS, has a direct impact on the environmental conditions that the microbiome (the bacteria that line the gut) must endure. Thus, we see a tight connection between the microbiome and the ENS. Furthermore, it has been shown that the ENS can even help maintain intestinal health by actually modulating the microbiome, in favour of anti-inflammatory strains of bacteria (4). However, this relationship goes both ways, as we see that when the microbiome is depleted with the use of antibiotics, there is dysfunction in the ENS and gastrointestinal disorders arise (5).
There is now overwhelming evidence suggesting that the gut microbiome plays a role in regulating brain function and behaviour. The healthy bacteria in the gut produce a wide range of neuroactive substances including catecholamines, γ-aminobutyric acid, melatonin, and serotonin, all of which play a role in the regulation of emotions, mood, and behavior (6). For example, serotonin is known as our “happiness” neurotransmitter, which helps improve our mood. However, it is also crucial in the regulation of peristalsis, the wave like contractions in the gut, and modulation of sensation (7). It is interesting that the most commonly prescribed drugs for treating anxiety and depression, like Prozac, Zoloft, and Celexa, work by modulating levels of serotonin. Thus, the emerging concept of this microbiome-gut-brain axis suggests that modulation of the gut bacteria may be a strategy for developing a new approach for treatment for behavioural and mood disorders.
Gut-Brain Connection in Action
Some doctors are beginning to address digestive concerns with the gut-brain connection in mind. Antidepressants are now being used to treat Irritable Bowel Syndrome (IBS). This is not because doctors believe that IBS symptoms are “all in the head”, but because antidepressants have activity on the chemicals and nerve cells in the gut (8).
Another example of this is with the use of probiotics. Research shows that probiotic treatment reduces anxiety, decreases the stress response, and normalizes behavior in humans (9). Interestingly, this is a bidirectional relationship, and stress has also been shown to disrupt the composition of gut bacteria (10).
Autism is another disorder that helps to confirm this connection between the gut and the brain. Autism is a neurodevelopmental disorder that begins in childhood. Children with autism are prone to GI symptoms such as constipation, diarrhea and inflammatory bowel disease (11). This supports the gut-brain connection as we see the presence of inflammation in the gut lining in those with autism, which leads to increased permeability of the walls of the gut allowing damaging substances to pass through (11). It is also reported that children with autism have a compromised blood-brain-barrier, the barrier that protects the brain from harmful substances (12). Given that there is an impairment in both the intestinal and blood-brain barriers, those with autism have inflammatory substances entering the brain and triggering inflammation in the nerve cells (11).
How to Optimize Your Brain, By Way of Your Gut
- Identify any food sensitivities that may be leading to inflammation and disruption in your gut bacteria
- Include probiotic-rich foods like kefir and sauerkraut. If these aren’t your favourite, a probiotic supplement may be an easy addition to your routine
- Stress management is key – finds ways to reduce stress that work for you
- Work with a naturopathic doctor or functional medicine practitioner to determine the underlying cause of your concerns
Written by Dr. Bronwyn Storoschuk, ND. As a board certified naturopathic doctor, health advocate and professional problem solver, Dr. Bronwyn offers personalized care, appreciating the uniqueness of each individual. She works to optimize the health of women with ambition to enable a vibrant and thriving life. She has a special interest in Women’s Health, including hormonal imbalance, reproductive health and fertility, and weight loss.
- Furness J., Callaghan B., Rivera L., Cho H. 2014. The enteric nervous system and gastrointestinal innervation: integrated local and central control. Adv Exp Med Biol; 817:39-71.
- Johns Hopkins Medicine. The Brain-Gut Connection. https://www.hopkinsmedicine.org/health/healthy_aging/healthy_body/the-brain-gut-connection
- Avetisyan M, Schill EM, Heuckeroth RO. 2015. Building a second brain in the bowel. The Journal of Clinical Investigation;125(3):899-907.
- Rolig AS, Mittge EK, Ganz J, et al. 2017. The enteric nervous system promotes intestinal health by constraining microbiota composition. Gore J, ed. PLoS Biology;15(2):e2000689.
- Brun P., Giron M. C., Qesari M., Porzionato A., Caputi V., Zoppellaro C., et al. 2013. Toll-like receptor 2 regulates intestinal inflammation by controlling integrity of the enteric nervous system. Gastroenterology 1451323–1333. 10.1053/j.gastro.2013.08.047
- Petra AI, Panagiotidou S, Hatziagelaki E, Stewart JM, Conti P, Theoharides TC. 2015. Gut-microbiota-brain axis and effect on neuropsychiatric disorders with suspected immune dysregulation. Clinical therapeutics;37(5):984-995.
- Talley N. 2001. Serotoninergic neuroenteric modulators. Lancet; 358: 2061-2068
- Clouse RE. 2003. Antidepressants for irritable bowel syndrome. Gut;52(4):598-599.
- Luna R. A., Foster J. A. 2015. Gut brain axis: diet microbiota interactions and implications for modulation of anxiety and depression.Curr. Opin. Biotechnol. 32: 35–41.
- Dinan T., and Cryan J. 2012. Regulation of the stress response by the gut microbiota; implications for psychoneuroendocrinology. Psychoneuroendocrinology; 37: 1369-1378.
- Li Q, Han Y, Dy ABC, Hagerman RJ. 2017. The Gut Microbiota and Autism Spectrum Disorders. Frontiers in Cellular Neuroscience;11:120.
- Medscape. 2017. More Support for Gut-Brain Link in Autism Accessed on Mar. 10, 2018.