Irritable bowel syndrome, commonly abbreviated to IBS, is an umbrella term used to describe a set of intestinal symptoms that tend to occur together. These symptoms can vary in duration and severity and differ from person to person. However, they tend to typically last for at least three months for at least three days or more per month. In some cases, irritable bowel disease can cause intestinal damage, though it is not that common. Meanwhile, serotonin is a neurotransmitter that is responsible for controlling and stabilizing a person’s mood and functions in the brain. It surprises many to know that serotonin is also critical for the proper functioning of the digestive system.
According to some research, targeting serotonin in the gut can help in the treatment of irritable bowel syndrome. Read on to find out more about irritable bowel syndrome and serotonin and if it can help.
Serotonin and Irritable Bowel Syndrome
Serotonin is an important chemical messenger or neurotransmitter that is responsible for controlling and stabilizing your mood.(1,2,3,4) Serotonin also plays a critical role in ensuring the proper functioning of the brain. It surprises many to know that serotonin can also be vital to the proper functioning of the digestive system. After all, the gut manufactures almost 95 percent of the serotonin in the body, and any changes in the level of serotonin in the body have a direct effect on your gut and your brain.(5,6,7,8)
Irritable bowel syndrome (IBS) is a common condition that affects the large intestine.(9,10) While the causes of irritable bowel syndrome are not clearly understood yet, some of the common symptoms of this condition include:
Irritable bowel syndrome is characterized by episodes of flare-ups, during which your symptoms get worse, and periods of remission, during which your symptoms either disappear or reduce in severity. Flare-ups of IBS can last for days, weeks, or even months in some cases.(11)
A 2009 study found that serotonin can help in the treatment of irritable bowel syndrome.(12) Read on more about this connection and if serotonin can actually help treat irritable bowel syndrome.
What is the Brain-Stomach Link?
Located in your stomach is the enteric nervous system, which is a type of semiautonomous nervous system that is embedded into the lining of the gastrointestinal system.
There are hundreds of millions of nerve cells that directly move through the enteric nervous system. This system is capable of performing various functions on its own as it is believed to be independent of the brain. Some of these tasks include coordination of reflexes and secretion of enzymes, serotonin being one of them.(13)
There are neural pathways connected to the enteric nervous system and your brain, and it is believed that each one affects the other. For example, feeling butterflies in your stomach when you are nervous or suddenly feeling the need to use the bathroom when you are feeling anxious, even though you have just used the bathroom.(14,15)
At the same time, it has been observed that flare-ups of irritable bowel syndrome can be brought on by anxiety and stress from the brain.
What is the Role of Serotonin?
Serotonin has a crucial role to play in the communication that takes place between your brain and the gut and also in ensuring proper functioning of the stomach.(16)
Serotonin is known to impact many parts of your gut functions, including:
- The sensitivity level of your intestines to sensations like fullness from eating and pain.
- How much fluid, like mucus, gets secreted in the intestines?
- How quickly the food moves through your digestive system?
There are specific nerve receptors that are responsible for sending communication to the brain, which in turn signals the brain about pain, bloating, and nausea. Other nerve receptors affect how a person experiences full or distended intestines.
The levels of each of these nerve receptors vary from person to person. For example, one person’s stomach may interpret the normal feeling of fullness as pain, while another might not.
It has been found that people with irritable bowel syndrome who experience constipation more often have lower levels of serotonin. The muscles in their rectums are also found to be less reactive to serotonin, and they tend to behave more lumpy or hard stools.(17,18)
Comparatively, people with the condition who have high levels of serotonin are more likely to experience diarrhea, and their rectums are also more reactive, with watery or loose stools.(19)
IBS Symptoms and Serotonin Challenges
Patients with irritable bowel syndrome have to deal with a wide range of symptoms, including some that are not even related to the bowel.
Having low levels of serotonin is more likely to make you susceptible to fibromyalgia, a condition that causes increased sensitivity to pain in various muscles of the body. A change in the levels of serotonin can also disrupt your sleeping patterns and are also linked with anxiety disorders and chronic depression.(20,21,22)
In people with irritable bowel syndrome and depression, doctors are likely to prescribe a class of drugs known as selective serotonin reuptake inhibitors (SSRIs). This class of drugs allows more serotonin to become available for the nerve cells to use. However, anti-anxiety medications and antidepressants are not going to help treat your irritable bowel syndrome.
Research is ongoing to search for medications that are specially designed for treating these serotonin changes that are observed in irritable bowel syndrome but without having other damaging side effects.
You can always talk to your doctor about the current and emerging serotonin therapies that can help address your symptoms. However, at the same time, it is essential to remember that exercise and techniques like meditation and yoga can also help change the serotonin levels in the body to bring about a positive impact on your symptoms.
The nervous systems of the gut and the brain are integrally connected to one another through neural pathways. The neurotransmitter serotonin plays a critical role in both these systems, being responsible for regulating essential functions in the body along with your mood. Serotonin is believed to affect the symptoms of irritable bowel syndrome, and changing the serotonin levels with medications, exercise, and meditation, can help you deal with these symptoms.
- Mohammad‐Zadeh, L.F., Moses, L. and Gwaltney‐Brant, S.M., 2008. Serotonin: a review. Journal of veterinary pharmacology and therapeutics, 31(3), pp.187-199.
- Berger, M., Gray, J.A. and Roth, B.L., 2009. The expanded biology of serotonin. Annual review of medicine, 60, pp.355-366.
- Jacobs, B.L. and Azmitia, E.C., 1992. Structure and function of the brain serotonin system. Physiological reviews, 72(1), pp.165-229.
- Geyer, M.A. and Vollenweider, F.X., 2008. Serotonin research: contributions to understanding psychoses. Trends in pharmacological sciences, 29(9), pp.445-453.
- Bornstein, J.C., 2012. Serotonin in the gut: what does it do?. Frontiers in neuroscience, 6, p.16.
- https://www.apa.org. 2021. That gut feeling. [online] Available at: <https://www.apa.org/monitor/2012/09/gut-feeling> [Accessed 30 January 2021].
- Banskota, S., Ghia, J.E. and Khan, W.I., 2019. Serotonin in the gut: Blessing or a curse. Biochimie, 161, pp.56-64.
- Ahlman, H., Bhargava, H.N., Dahlström, A., Larsson, I., Newson, B. and Pettersson, G., 1981. On the presence of serotonin in the gut lumen and possible release mechanisms. Acta physiologica Scandinavica, 112(3), pp.263-269.
- Whitehead, W.E., Engel, B.T. and Schuster, M.M., 1980. Irritable bowel syndrome. Digestive diseases and sciences, 25(6), pp.404-413.
- Camilleri, M. and Choi, M.G., 1997. Irritable bowel syndrome. Alimentary pharmacology & therapeutics, 11(1), pp.3-15.
- Francis, C.Y., Morris, J. and Whorwell, P.J., 1997. The irritable bowel severity scoring system: a simple method of monitoring irritable bowel syndrome and its progress. Alimentary pharmacology & therapeutics, 11(2), pp.395-402.
- Sikander, A., Rana, S.V. and Prasad, K.K., 2009. Role of serotonin in gastrointestinal motility and irritable bowel syndrome. Clinica Chimica Acta, 403(1-2), pp.47-55.
- Ridaura, V. and Belkaid, Y., 2015. Gut microbiota: the link to your second brain. Cell, 161(2), pp.193-194.
- Blakeslee, S., 1996. Complex and hidden brain in gut makes stomachaches and butterflies. New York Times, 23.
- Boeree, G.C., 2009. The emotional nervous system. General psychology.
- Baker, D.E., 2005. Rationale for using serotonergic agents to treat irritable bowel syndrome. American Journal of Health-System Pharmacy, 62(7), pp.700-711.
- Miwa, J., Echizen, H., Matsueda, K. and Umeda, N., 2001. Patients with constipation-predominant irritable bowel syndrome (IBS) may have elevated serotonin concentrations in colonic mucosa as compared with diarrhea-predominant patients and subjects with normal bowel habits. Digestion, 63(3), pp.188-194.
- Shekhar, C., Monaghan, P.J., Morris, J., Issa, B., Whorwell, P.J., Keevil, B. and Houghton, L.A., 2013. Rome III functional constipation and irritable bowel syndrome with constipation are similar disorders within a spectrum of sensitization, regulated by serotonin. Gastroenterology, 145(4), pp.749-757.
- Camilleri, M., Atanasova, E., Carlson, P.J., Ahmad, U., Kim, H.J., Viramontes, B.E., Mckinzie, S. and Urrutia, R., 2002. Serotonin-transporter polymorphism pharmacogenetics in diarrhea-predominant irritable bowel syndrome. Gastroenterology, 123(2), pp.425-432.
- Stein, D.J. and Stahl, S., 2000. Serotonin and anxiety: current models. International clinical psychopharmacology, 15, pp.S1-6.
- Meltzer, H.Y., 1990. Role of Serotonin in Depression a. Annals of the New York Academy of Sciences, 600(1), pp.486-499.
- Baldwin, D. and Rudge, S., 1995. The role of serotonin in depression and anxiety. International clinical psychopharmacology.
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