Antidepressants are a class of medication used to treat depression and other mental health disorders, such as anxiety, obsessive-compulsive disorder (OCD), and post-traumatic stress disorder (PTSD). There are several types of antidepressants available, including selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), and monoamine oxidase inhibitors (MAOIs). The use of antidepressants has increased significantly over the past few years, with antidepressant prescribing rising by a staggering 35% in six years.1 However, while antidepressants have been effective in treating depression, anxiety, and other mental health conditions, there is growing concern about the link between antidepressants and gut health.
The gut is often referred to as the “second brain” due to its complex network of neurons and neurotransmitters. The gut and the brain are connected via a bidirectional communication system known as the gut-brain axis.2 This axis allows the gut to communicate with the brain and vice versa. It also plays a crucial role in regulating mood, behaviour, and cognitive function. Imbalances in this system have been linked to various mental health conditions, including depression and anxiety.3 Antidepressants are thought to work by altering the levels of neurotransmitters in the brain. Still, they may also affect the gut-brain axis and the microbiome.
Antidepressants and Gut Health: The Gut Microbiome
Several studies have suggested that there may be a connection between antidepressant use and gut health. For example, research has shown that antidepressants can alter the composition of the gut microbiome. In particular, SSRIs are known to reduce the diversity of the gut microbiome and change the abundance of specific bacterial species.4 Interestingly, the antimicrobial effects of antidepressants on the gut microbiome may depend on the dose and type of treatment.5
Antidepressants and Digestive Function
In addition to altering the microbiome, antidepressants may negatively affect digestive function. This is because many of the neurotransmitters that are targeted by these medications are also involved in regulating digestion. Antidepressant drugs, such as SSRIs, are known to affect gut motility, which may contribute to the development of gastrointestinal symptoms such as nausea, diarrhoea, and constipation as side effects of these medications. These side effects can be particularly problematic for individuals with digestive issues, such as irritable bowel syndrome (IBS).
Antidepressants may also interfere with the absorption of nutrients via the digestive tract. For example, antidepressants may potentially reduce niacin and NAD levels in individuals with poor dietary intake.6 Worryingly, a 2018 systematic review and meta-analysis described a connection between the use of SSRIs and an increased risk of fracture, particularly with prolonged usage, with age not seeming to be a contributing factor.7
Antidepressants and the Immune System
Research suggests that antidepressants can modify various aspects of immune cell function.8 Given that the gut contains a large number of immune cells, these findings suggest that SSRIs could have important effects on the functioning of the immune system within the gut.
Inflammation is a natural response of the immune system to injury or infection. However, chronic inflammation has been linked to various health conditions, including depression and anxiety. Antidepressants may exert their therapeutic effects by helping to reduce inflammation through modulation of the immune system.9
Antidepressants may, in fact, exert a positive effect on gut health through their potential anti-inflammatory properties. Some studies suggest that antidepressants may be effective in treating gut-related disorders, such as IBS.10
Summing Up
Antidepressants are a commonly prescribed medication for people struggling with mental health conditions. However, like most medications, antidepressants are associated with a range of side effects, some of which affect the gut and digestive system.
However, recent research has shown that there may also be a potential therapeutic benefit to antidepressants in relation to gut health. Certain types of antidepressants, particularly those that target serotonin, can help reduce inflammation in the gut. Inflammation is a key factor in a range of gut-related health problems, including IBS, Crohn’s disease, and ulcerative colitis. By reducing inflammation, antidepressants may be able to provide relief from these conditions, as well as improve overall gut health.
Although gut-related side effects are a frequently reported issue with antidepressant use, it is worth noting that there could be potential therapeutic advantages to taking these medications to improve gut health. If you are presently taking antidepressants and experiencing symptoms related to your gut, it is imperative to seek advice from your healthcare provider to ascertain the optimal plan of action.
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References
1. Pharmaceutical Journal. (2022, July 8). Antidepressant prescribing increases by 35% in six years. Retrieved from https://pharmaceutical-journal.com/article/news/antidepressant-prescribing-increases-by-35-in-six-years
2. Carabotti, M., Scirocco, A., Maselli, M. A., & Severi, C. (2015). The gut-brain axis: Interactions between enteric microbiota, central and enteric nervous systems. Annals of Gastroenterology : Quarterly Publication of the Hellenic Society of Gastroenterology, 28(2), 203-209.
3. Foster, J. A., & McVey Neufeld, K. A. (2013). Gut-brain axis: how the microbiome influences anxiety and depression. Trends in Neurosciences, 36(5), 305–312.
4. Lukić, I., Getselter, D., Ziv, O., Oron, O., Reuveni, E., Koren, O., & Elliott, E. (2019). Antidepressants affect gut microbiota and Ruminococcus flavefaciens is able to abolish their effects on depressive-like behavior. Translational Psychiatry, 9.
5. Chait, Y. A., Mottawea, W., Tompkins, T. A., & Hammami, R. (2020). Unravelling the antimicrobial action of antidepressants on gut commensal microbes. Scientific Reports, 10.
6. Viljoen, M., Swanepoel, A., & Bipath, P. (2015). Antidepressants may lead to a decrease in niacin and NAD in patients with poor dietary intake. Medical Hypotheses, 84(3), 178–182.
7. Khanassov, V., Hu, J., Reeves, D., & van Marwijk, H. (2018). Selective serotonin reuptake inhibitor and selective serotonin and norepinephrine reuptake inhibitor use and risk of fractures in adults: A systematic review and meta-analysis. International Journal of Geriatric Psychiatry, 33(12), 1688–1708.
8. Szałach, Ł. P., Lisowska, K. A., & Cubała, W. J. (2019). The Influence of Antidepressants on the Immune System. Archivum Immunologiae et Therapiae Experimentalis, 67(3), 143-151.
9. Dionisie, V., Filip, G. A., Manea, M. C., & Păcală, L. E. (2021). The anti-inflammatory role of SSRI and SNRI in the treatment of depression: A review of human and rodent research studies. Inflammopharmacology, 29(1), 75-90.10.
10. Ford, A. C., Talley, N. J., Schoenfeld, P. S., Quigley, E. M., & Moayyedi, P. (2009). Efficacy of antidepressants and psychological therapies in irritable bowel syndrome: systematic review and meta-analysis. Gut, 58(3), 367–378.
