How Does Caffeine Affect the Gut?
There are many reasons why so many of us love our coffee. For some, the taste of freshly brewed coffee can be enough motivation to get us out of bed in the morning. For others, it could be the reliable energy-boost that helps to improve focus and productivity. No matter the reason, if you’re a coffee-lover you may be wondering whether your morning cup of java is good for you and your gut. Most likely, you have experienced the first-hand effects caffeine can have on your digestive system - perhaps a run to the toilet after it goes down a little too well. So, what’s going on in our digestive system when we have caffeine?
How does caffeine work?
Caffeine acts as a stimulant which can increase alertness and have mood-enhancing effects, helping us feel more awake and energised.
Are there any downsides to having caffeine?
Caffeine can cause unpleasant symptoms, and having too much caffeine can be quite irritating for the gut. Some considerations include:
- Caffeine can trigger irritable bowel syndrome (IBS) symptoms and IBS flares, as well as trigger symptoms for those with reflux or GORD
- Individuals who are prone to anxiety and nervousness may have symptoms exacerbated when they have too much caffeine.
- Caffeine has a long half-life, meaning that it stays in the body for a long period of time. Having a lot of caffeine or having it too late in the day can impact your ability to fall asleep as well as the quality of sleep.
- What sources of caffeine are you having? Sources of caffeine like cola, caffeinated drinks with lots of added sugar, and energy drinks can contain high amounts of added sugar and negatively impact the gut microbiota by reducing the activity and diversity of intestinal bacteria!
How can caffeine benefit our gut health?
In addition to helping us wake up, caffeine has several effects on our digestive system. It can increase muscle contractions in the intestines which can help regulate movements, acting as a natural laxative by increasing gut motility and relieving constipation. While research is still emerging, there is also some evidence to suggest that caffeine can change the makeup of the gut microbiota by increasing beneficial bacteria such as Bifidobacteria and reducing the growth of harmful bacteria. Coffee and other sources of caffeine are a source of polyphenols and other compounds which may feed gut bacteria, have anti-inflammatory effects, and act as an antioxidant – all of which are beneficial to gut health. However, the key here is the amount of caffeine you have!
So, how much should you have?
It is best to have no more than 400mg per day and less than 200mg per day if pregnant. Some individuals are more sensitive to caffeine, so it’s important to consider individual needs. Below is a guide to how much caffeine is typically found in common drinks and food.
- Espresso: 100mg caffeine per shot
- Green tea: 30mg per cup
- Black tea: 30mg caffeine per cup
- Dark chocolate: 40mg per 50g
- Cola: 25mg per 250ml
- Instant coffee: 90mg per tsp
The bottom line
There is research to suggest that caffeine may be beneficial for gut health including helping to regulate bowel movements, increase the balance of good and bad microbes, and have an anti-inflammatory effect in the gut. Having too much caffeine though can irritate the gut and result in unwanted symptoms, particularly among those who are sensitive to caffeine. Individual considerations should always be taken into account, but aiming for less than 400mg a day is generally recommended.
 Alsunni, AA. (2015). Energy Drink Consumption: Beneficial and Adverse Effects. International Journal of Health Sciences, 9(4):468-474.
 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), 88. https://doi.org/10.3390/nu13010088
 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
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