The important role of serotonin in your gut

Have you heard of serotonin? Many people have heard of this chemical due to its ability to promote feelings of happiness and wellbeing. What is less known, is that serotonin also plays important roles within our digestive tract, pancreas, liver and bones1,2. Serotonin is mostly produced in your gut – where so many of our beneficial substances are formed!

Most of our serotonin (approx. 90%) is produced in the gut by special cells, called enterochromaffin (EC) cells, found within the lining of the intestinal wall3,4. Interestingly, serotonin cannot cross from the body to the brain, and therefore, our brains produce their own serotonin (approx. 5%)5. Serotonin produced in the brain acts as a type of chemical messenger called a neurotransmitter and helps regulate learning, behaviour, mood and appetite4. Whereas serotonin in the body acts more like a hormone and regulates things like glucose and fat metabolism, gut inflammation, and gut motility2,5.

Your gut bacteria and serotonin

Our gut bacteria – which live in a community inside our large intestine known as the gut microbiome – produce by-products that can stimulate the production of serotonin from the EC cells6. These by-products include secondary bile acids2 and the short chain fatty acids (SCFAs) butyrate and propionate2,7. Once released, serotonin helps regulate sensory, motor and secretory functions in the body through interacting with different serotonin receptors8. Recently, an animal study found that gut bacteria not only influenced the level of serotonin production but that serotonin production in the gut was protective against pathogenic species invading and causing illness9.

Why are prebiotics important for your gut health? Learn more.

Your diet and serotonin

Did you know that you can encourage the production of beneficial substances such as serotonin through what you eat? In general, eating a diet with adequate levels of prebiotic fibres (commonly found in plant foods) helps to support a health-promoting gut microbiome. Prebiotic fibres support the growth of SCFA-producing bacterial species that can stimulate serotonin production. Importantly, serotonin production in the gut is reliant on the intake of specific nutrients that can be gained by eating a balanced diet.

Tryptophan, an essential amino acid, is the building block for serotonin production in both the brain and gut10. Being an essential amino acid, tryptophan, cannot be made by our bodies and must be obtained through diet. Oats, bananas, milk, tuna, cheese, bread, poultry and peanuts are common foods that contain tryptophan. Serotonin production from tryptophan also requires nutrients such as vitamin B6 (pyridoxine), vitamin B3 (niacin), and glutathione (an antioxidant predominantly produced by the body)11.

Serotonin summed up

Serotonin plays many roles in the human body and most of our production occurs in the gut. Adequate prebiotic fibres help to support gut bacteria that produce SCFAs which can stimulate serotonin production.

The good news is that many common foods contain the nutrients required to support serotonin production. You can consume a wide variety of foods from across all five food groups to help support the body in producing adequate serotonin levels. Now that you know you can support serotonin production through food, learn more about the connection between food and mood.

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Interested in learning more about your gut microbiome and role it plays in serotonin production? We recommend discussing the Co-Biome MetaXplore range with your healthcare professional or finding a Co-Biome Certified Clinician to learn more.

Yano JM, Yu K, Donaldson GP, Shastri GG, Ann P, Ma L, Nagler CR, Ismagilov RF, Mazmanian SK, Hsiao EY (April 2015). "Indigenous bacteria from the gut microbiota regulate host serotonin biosynthesis",. Cell. 161 (2): 264–76. doi:10.1016/j.cell.2015.02.047. PMC 4393509. PMID 25860609.
Martin AM, Young RL, Leong L, Rogers GB, Spencer NJ, Jessup CF, Keating DJ. (2017).. The Diverse Metabolic Roles of Peripheral Serotonin,. Endocrinology, 2017; Volume 158, Issue 5, Pages 1049–1063,
Bertrand, Paul P.; Bertrand, Rebecca L. (2010). . "Serotonin release and uptake in the gastrointestinal tract". . Autonomic Neuroscience. 153 (1–2): 47–57. doi:10.1016/j.autneu.2009.08.002. PMID 19729349.
Jenkins TA, Nguyen JC, Polglaze KE, Bertrand PP. (2016).. Influence of Tryptophan and Serotonin on Mood and Cognition with a Possible Role of the Gut-Brain Axis. . Nutrients. 2016;8(1):56. Published 2016 Jan 20. doi:10.3390/nu8010056.
El-Merahbi R, Löffler M, Mayer A, Sumara G. (2015).. The roles of peripheral serotonin in metabolic homeostasis.. FEBS Lett. 2015;589(15):1728-1734. doi:10.1016/j.febslet.2015.05.054.
McKinney, J., Knappskog, P.M. and Haavik, J. (2005).. Different properties of the central and peripheral forms of human tryptophan hydroxylase. . Journal of Neurochemistry, 92: 311-320. doi:10.1111/j.1471-4159.2004.02850.
Fukumoto S, Tatewaki M, Yamada T, et al. (2003).. Short-chain fatty acids stimulate colonic transit via intraluminal 5-HT release in rats. . Am J Physiol Regul Integr Comp Physiol. 2003;284(5):R1269-R1276. doi:10.1152/ajpregu.00442.2002.
Stasi C, Bellini M, Bassotti G, Blandizzi C, Milani S. (2014).. Serotonin receptors and their role in the pathophysiology and therapy of irritable bowel syndrome. . Tech Coloproctol. 2014;18(7):613-621. doi:10.1007/s10151-013-1106-8.
Kumar A, Russell RM, Pifer R, Menezes-Garcia Z, Cuesta S, Narayanan S, MacMillan JB, Sperandio V. (2020).. The serotonin neurotransmitter modulates virulence of enteric pathogens. . Cell Host & Microbe. 2020;28:1-13. doi:10.1016/j.chom.2020.05.004.
Richard DM, Dawes MA, Mathias CW, Acheson A, Hill-Kapturczak N, Dougherty DM. (2009).. L-Tryptophan: Basic Metabolic Functions, Behavioral Research and Therapeutic Indications. . Int J Tryptophan Res. 2009;2:45-60. doi:10.4137/ijtr.s2129.
National Center for Biotechnology Information. (2020).. PubChem Compound Summary for CID 6305, Tryptophan. . Accessed Aug. 5, 2020.