A morning cup of coffee is an inevitable part of the day in many households worldwide. This beverage proudly carries its label “the favorite drink of the civilized world” with many people consuming a cup or two (or five and more) every day. It’s especially popular for its ability to decrease fatigue and improve cognitive functions. This benefit can be attributed to caffeine, the main compound present not only in coffee but also tea and other caffeinated beverages. Despite its popularity, IBS patients often report worsening of their symptoms after drinking coffee. (1.)
How does coffee affect digestion?
It stimulates colonic intestinal motility
It was found that the transit of food through the colon increases rapidly about 4 minutes after coffee consumption. The transit of food is faster due to the increased frequency of intestinal contractions. This leads to a greater desire to defecate and might worsen the symptoms of IBS, especially for patients with the IBS-D subtype.
It also stimulates the secretion of gastrin
Gastrin, a hormone secreted by so-called G-cells in the stomach, causes the release of hydrochloric acid and digestive enzymes which enhance digestion and intestinal motility (movement of food through the intestines). This effect happens after drinking both caffeinated and decaffeinated coffee.
Although it is recommended that IBS-D patients avoid drinking coffee, the IBS-C subtype may benefit from these effects. It was shown that it could potentially contribute to relieving constipation but only if it does not cause other problems. (2.)
Is it better to avoid it completely?
The answer to this question is not straightforward. Although coffee is currently part of the list of many dietary triggers that IBS patients should avoid, in a recently published study by the International Journal of Epidemiology, it was found that its consumption might in the long term lower the risk of IBS. The study surveyed almost half a million UK inhabitants and found that higher coffee intake could indeed lower the risk of IBS by up to 19%. There are several possible explanations.
Coffee has anti-inflammatory properties
Caffeine, combined with other compounds found in coffee (such as chlorogenic acids), is found to reduce inflammation in the body. Inflammation is associated with abdominal pain, anxiety and mood disorders. (1.) There are other effective ways to combat inflammation that include proper diet, regular exercise, and less exposure to stress.
Roasted coffee contains melanoidins
Melanoidins are compounds formed during the roasting process. These compounds have several beneficial properties. They lower blood pressure, decrease inflammation, and inhibit growth of pathogenic bacteria. The amount of melanoidins, however, depends on the roasting conditions and the quality of the coffee. (4.)
Polyphenols and dietary fiber found in coffee help restore gut microbiota
In a study performed in Switzerland, it was found that increased coffee consumption for a period of 3 weeks increased gut microbial diversity. It is a well-known fact that gut dysbiosis (imbalance between “good” and “bad” gut bacteria) contributes to the development of IBS. Coffee components such as polyphenols and dietary fiber seem to stimulate the growth of “good” bacteria in the gut, predominantly Bifidobacteria. Bifidobacteria are often found in lower abundance in constipated patients. It was also reported that caffeinated coffee may inhibit the growth of pathogenic bacteria in the gut such as E. coli. (2.)
It is a good source of tryptophan
Tryptophan is an essential amino acid (also found in meat, dairy, nuts, etc.) that must be obtained from the diet. Among other things, tryptophan is important for serotonin synthesis. (5.) Serotonin is a hormone that controls your mood and brain functions. Approximately 95% of serotonin is produced in the gut and it is crucial for proper gut function. It affects how fast a meal moves through the intestines or how sensitive your intestines are to pain. People with IBS-C subtype usually have lower levels of serotonin and, on the other hand, people with IBS-D have increased levels of serotonin. It is still unclear why. (4.)
Summary
Coffee is an interesting mixture of several compounds whose effects vary depending on where it came from or how it was processed. It is a popular beverage in every country and many of its properties are still a mystery to current science. That is why we often refer to the ‘coffee paradox’. For example, coffee seems to lower the risk of high blood pressure but caffeine itself raises blood pressure. (5.) So, while coffee seems to protect some, it may also be an IBS trigger for others. If you don’t want to completely cut it out, our recommendation is to try elimination diet and slowly reintroduce coffee in the amounts that do not lead to worsening of your symptoms. It is, however, not recommended to consume more than 1,5 dl three times a day.
References
- Romualdo, G. R., Rocha, A. B., Vinken, M., Cogliati, B., Moreno, F. S., Chaves, M. A. G., & Barbisan, L. F. (2019). Drinking for protection? Epidemiological and experimental evidence on the beneficial effects of coffee or major coffee compounds against gastrointestinal and liver carcinogenesis. Food Research International, 123, 567–570. https://doi.org/10.1016/j.foodres.2019.05.029
- Nehlig, A. (2022). Effects of Coffee on the Gastro-Intestinal Tract: A Narrative Review and Literature Update. Nutrients, 14(2), 399. https://doi.org/10.3390/nu14020399
- Wu, S., Yang, Z., Yuan, C., Liu, S., Zhang, Q., Zhang, S., & Zhu, S. (2023). Coffee and tea intake with long-term risk of irritable bowel syndrome: a large-scale prospective cohort study. International Journal of Epidemiology, dyad024. https://doi.org/10.1093/ije/dyad024
- How Does Serotonin in the Brain Affect Your Bowels? (2020, November 4). Healthline. https://www.healthline.com/health/irritable-bowel-syndrome/serotonin-effects
- Iriondo-DeHond, A., Uranga, J. A., del Castillo, M. D., & Abalo, R. (2020). Effects of Coffee and Its Components on the Gastrointestinal Tract and the Brain–Gut Axis. Nutrients, 13(1). https://doi.org/10.3390/nu13010088
