The Power of Your Gut: Overview of the Gut Microbiota's Role in Mental Health

People frequently perceive mental health as solely confined to the realm of the mind, yet its intricacies extend far beyond. Our gut health, for one, plays a pivotal role in dictating your mental well-being (1,6)

Your gastrointestinal (GI) system consists of all the organs involved in nutrient metabolism, including your mouth, esophagus, stomach, small intestine, large intestine (colon) and anus. Trillions of organisms are found along the GI tract. These organisms include bacteria, viruses, fungi and archaea. In recent years, more light has been shed on the immense impact gut bacteria play on mental health and brain function; the gut-brain connection.

The gut-brain axis refers to the bidirectional communication network connecting the gut (the gastrointestinal tract) with the brain (the central nervous system), enabling constant interaction between the two systems. Gut bacteria  exert their influence on the gut-brain axis in several ways:

Neurotransmitter Production: Gut bacteria can produce neurotransmitters, which are are chemicals that directly affect mood and emotions. For example, certain strains of gut bacteria can make gamma-aminobutyric acid (GABA), a neurotransmitter that helps reduce anxiety and promote relaxation. Gut bacteria can also indirectly influence neurotransmitter production by controlling the availability of key building blocks and metabolites needed for making mood-regulating neurotransmitters (2)

Hormone metabolism: Gut bacteria affect hormones like insulin, glucagon and estrogen. Dysregulation of Insulin and glucagon are indictors of metabolic disorders, like insulin resistance, diabetes and high cholesterol. More and more research is showing that metabolic disorders are, in essence, mental health disorders (3,6). Moreover, maintaining optimal estrogen levels is important because estrogen increases levels of feel-good chemicals: serotonin and dopamine. On the other hand, low estrogen levels contribute to poor mental health and make you more prone to mood swings (4). The collection of bacteria involved in managing levels of estrogen in the body is called the estrobolome.

Inflammation and Immunity: Gut bacteria play a role in maintaining the integrity of the gut barrier, our body’s protection against harmful substances. Imbalances can lead to leaky gut, allowing bacteria and toxins to enter our blood, causing chronic inflammation. Inflammation is associated with several mental health, mood and brain disorders, such as MDD and Bipolar. Some gut bacteria also play a role in digesting dietary fibers and starches, producing short-chain fatty acids (SCFAs). These short chain fatty acids have important anti-inflammatory properties (3).

Nutrient Absorption: Gut bacteria assist in breaking down complex nutrients into simpler forms that our bodies can absorb. Problems with nutrient absorption due to gut bacteria imbalances can lead to nutrient deficiencies. Certain nutrients are necessary for optimal which mental health and brain function, so inadequacies can represent as symptoms of mental health disorders, like anxiety, irritability, constant sadness and lack of motivation (5).

Vitamins synthesis: Gut bacteria play a crucial role in synthesizing certain vitamins, particularly B vitamins (like B12, B6, and folate) and vitamin K. These vitamins are essential for neurotransmitter synthesis, energy metabolism, and the maintenance of healthy brain cells.

It is clear that gut bacteria affect many aspects of our brain and mental health. Therefore, it is important that we maintain the proper balance and diversity of bacteria. An overgrowth of bad bacteria, not enough good bacteria, or an overall lack of diversity is called dysbiosis. Gut dysbiosis can wreak havoc on our mental health because it can cause systemic inflammation and interfere with optimal neurotransmitter production, hormone control, estrogen balance, digestion as well as, nutrition absorption (8)

Eating the right foods like probiotics and prebiotics in combination with lifestyle behaviours such as exercise is essential for creating the optimal environment for the right kind of bacteria to thrive. Work with a Registered Dietitian, such as my self, to learn how you can optimize your gut health to enhance mental health.

1. Ochoa-Repáraz, J., Ramelow, C. C., & Kasper, L. H. (2020). A gut feeling: the importance of the intestinal microbiota in psychiatric disorders. Frontiers in Immunology, 11, 510113

2. Liu, T., Feenstra, K. A., Heringa, J., & Huang, Z. (2020). Influence of gut microbiota on mental health via neurotransmitters: a review. Journal of Artificial Intelligence for Medical Sciences, 1(1-2), 1-14.

3. Wang PX, Deng XR, Zhang CH, Yuan HJ. Gut microbiota and metabolic syndrome. Chin Med J (Engl). 2020 Apr 5;133(7):808-816. doi: 10.1097/CM9.0000000000000696. PMID: 32106124; PMCID: PMC7147654.

4. Maeng, L. Y., & Beumer, A. (2023). Never fear, the gut bacteria are here: Estrogen and gut microbiome-brain axis interactions in fear extinction. International Journal of Psychophysiology, 189, 66-75.

5. Krajmalnik-Brown R, Ilhan ZE, Kang DW, DiBaise JK. Effects of gut microbes on nutrient absorption and energy regulation. Nutr Clin Pract. 2012 Apr;27(2):201-14. doi: 10.1177/0884533611436116. Epub 2012 Feb 24. PMID: 22367888; PMCID: PMC3601187.

6. Zhang YJ, Li S, Gan RY, Zhou T, Xu DP, Li HB. Impacts of gut bacteria on human health and diseases. Int J Mol Sci. 2015 Apr 2;16(4):7493-519. doi: 10.3390/ijms16047493. PMID: 25849657; PMCID: PMC4425030.

7. Barone, M., D'Amico, F., Brigidi, P., & Turroni, S. (2022). Gut microbiome–micronutrient interaction: The key to controlling the bioavailability of minerals and vitamins?. Biofactors, 48(2), 307-314.

8. Wibowo, S., & Pramadhani, A. (2024). Vitamin B, Role of Gut Microbiota and Gut Health. Vitamin B and Vitamin E-Pleiotropic and Nutritional Benefits.