How does coffee affect your gut?

Via the Q&A section of our site we got the following question: "I drink a ton of coffee. Is it unhealthy for my stomach?"

A good question! Right off the bat I want to say a resounding no: in moderation coffee is perfectly healthy for your gut and may even be an important part of stimulating routine bowel movements if you drink it regularly. That said, there's a few clarifying points about the question before we launch into an answer. First of all, "a ton" means different things to different coffee drinkers, but you don't want to be exceeding 4 cups of coffee per day simply based off caffeine content. For the purposes of my answer I'm going to assume we're within that threshold.

Next, a big qualifier includes what you're putting in your coffee. Milk, cream, and even non-dairy creamers can all wreck havoc on the GI tract for reasons we explore in our post on lactose intolerance. Artificial sweeteners can prompt diarrhea by pulling water into your colon. With that out of the way, what does research tell us about coffee and your gut?

This has been a topic of conversation in the research community for a long time, and there's a surprising amount of data on the topic. While coffee may prompt heartburn (aka reflux or GERD) in people who already experience the symptom, there's no association with coffee drinking leading to developing reflux disease, indigestion, or heartburn symptoms. If you're someone who experiences heartburn whenever you drink coffee, there is some argument over whether variations in terms of how it's prepared make any difference in whether or not you experience symptoms, but the acidity of what you drink does tend to correlate with symptoms.

Is there a difference between caffeinated and decaffeinated?

While caffeine has effects on multiple organ systems on your body - your GI tract included, acting as a stimulant - research has shown us that most of coffee's effect on the gut is largely preserved regardless of its caffeine content. While caffeine may give you an added "boost" (in more ways than one) in terms of how fast your gut moves, and may exacerbate heartburn compared to its decaf counterpart, a lot of coffee's effect derives from its acidity, volume, and ability to draw water into your gut (aka osmolality, explored further here). 

In fact, research has shown us that regardless of caffeine content, within four minutes of drinking coffee, there is a notable increase in movement at the complete opposite end of your GI tract - the very last part your colon (aka the sigmoid)! This effect lasts up to 30 minutes, and is pretty amazing considering it would theoretically take upwards of 30 hours for the coffee to actually reach that part of your gut. In case you find these statistics as fascinating as I do, one study concluded that your colon's activity after drinking coffee was 60% stronger compared to just drinking water and was 25% stronger than just drinking decaffeinated coffee.

The last thing I looked into was whether coffee had any association with developing GI cancer. While you can cherry pick individual studies that find a higher incidence of cancer among coffee drinkers, the overwhelming majority of research does not find this to be the case. In fact, there may even be a protective effect in drinking coffee, particularly in patients with liver disease.  One minor point I'll make is that if you experience sharp pains after drinking coffee, it's possible you have a gallstone - coffee can induce your gallbladder to contract - and I'd recommend talking to your doctor (see our article on the basics if that sentence sounds like gibberish to you).

This amount of information may have been exhaustive, but the good news is there's no harm in drinking coffee to recharge!

-The Gut Doc


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