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OK, we admit that this is not one of the great medical mysteries of all time. It is intriguing, though. You might think that researchers have far more important things to do than try to figure out can coffee make you poop, and if so, why? It turns out that they have been struggling over this coffee conundrum for years. There may now be a plausible explanation. It was presented a prestigious meeting of gastroenterologists.

Coffee Makes Him Go to the Bathroom:

Q. I have found that my body reacts in a very predictable manner to my morning cup of coffee. Usually within 5 to 10 minutes I have to go to the bathroom. Is it the caffeine or something else in coffee that stimulates the bowels?

Does the Caffeine in Coffee Make You Poop?

A. You are not the first person to notice this effect. We used to think the caffeine was responsible, but scientists have shown that both regular and decaf coffee stimulate colon activity (Gut, April 1, 1990).  Caffeinated coffee does seem to have a stronger effect, however (European Journal of Gastroenterology & Hepatology, Feb. 1998). 

How Many People Are “Moved” by Coffee?

The small study in the journal Gut cited above reported that 29 percent of the volunteers in their study claimed “that coffee induced a desire to defecate.” That could be right, but we would need to see much larger numbers to find that stat convincing. There were only 99 volunteers willing to participate in that research. The actual number could be substantially higher for all we know.

Does the Acid in Coffee Make You Poop?

Some scientists have attributed the laxative effect of coffee (regular or decaf) to its acid content. Chlorogenic acid can stimulate acid production in the stomach. The theory goes that this effect in turn triggers intestinal movements. So far, though, the data are not convincing.

Will the Magnesium in Coffee Make You Poop?

Some people suggest that coffee is high in the mineral magnesium. Everyone knows that magnesium has a laxative action. Just think Milk of Magnesia (magnesium hydroxide). A 2 oz cup of espresso has almost 50 mg of magnesium. But a regular cup of coffee has only about 7 mg of magnesium. That is not enough to get things moving.

What Really Makes Coffee Send You to the Bathroom?

Scientists have tested coffee in rats and found that both decaf and high-test increase the contraction power of intestinal muscle contractions. There are purported to be over 1000 different chemicals in coffee; hence the complex flavors and unique aroma. The researchers at the University of Texas, Galveston, did not identify which specific chemicals in coffee stimulate muscle movements within the digestive tract.

Coffee and the Microbiome:

The coffee treatments also changed the composition of the rats’ gut microbes, though no one is quite certain what that means for digestive health. One possible application of the coffee discovery is in the hospital, of all places.

When patients undergo abdominal surgery, they frequently develop something called post-operative constipation. When surgeons handle your intestines, the tissues tend to revolt by not resuming normal contractions for awhile. There are also the anesthetics, muscle relaxers, pain meds and the immobility of recovery. If coffee helps get the intestinal tract moving again, perhaps someday doctors will prescribe a cup of coffee in the days following abdominal surgery.

The investigators reported their research at a conference, Digestive Disease Week (DDW) 2019.

Share your own experience with coffee and trips to the bathroom in the comment section.

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  1. PAT

    Coffee has kept me regular for years, though I don’t know why. Recently I was in the hospital for open-heart surgery. Every day in the hospital the nurses plied me with stool softeners which, unfortunately, failed to move me. I laughingly asked for coffee one day, saying it would surely work, and one nurse was kind enough to slip me a small cup. It did its job! I spent another 18 days in the hospital where cajoling for more coffee did no good. Neither did double the amount of stool softeners relieve me. Going home was such a relief–in all ways.

  2. James W.

    For me it’s eating pancakes or waffles….thinking it must be the syrup.

  3. Sandra
    Durham NC

    In my opinion, I believe it’s the “heated water” that really causes the digestive movement. I suspect any heated liquid would do the same, especially after overnight bowel inactivity.

  4. Ann
    Cambridge MA

    I’m one who experiences the drink coffee/have to poop soon, reliably every day.

    Has anyone suggested or looked into the effect of hot versus cold coffee? Or even just hot water/hot tea?

    Ann B.

  5. Brianm14
    Charlotte, NC

    My late father, for all of the part of his 78 years that I knew him, always began the day with a 10 to 12-ounce glass of very warm water. (He never drank tea or coffee) He never suffered from constipation, and issue was settle soon after drinking the water. I have same result -any time of day-from my first cup of coffee of tea. Coffee seems to work better, perhaps because I consume it hotter and faster, and in a 12-ounce rather than eight- ounce quantity.

    I am a professional university physiologist, and have long thought there were several factors at play. One, reflexive or almost reflexive reaction to this volume hot liquid in the stomach. Two, this is reinfornced by becoming a learned response (to the point that I have to have my first cup of coffee before leaving my home or hotel room, even when going out to breakfast!). Thirdly, this fluid consumption helps combat dehydration, a major cause of constipation. (I once worked with a gastroenterologist who started his
    treatment plan for chronic constipation with an order for six or more glasses of water a day, and it usually worked!)

  6. Frank B.

    Any hot liquid in the morning does this…hot chocolate, hot broth, even hot water. I think it’s just the hot liquid that has “trained” my gut to go into action in the morning…after all, I’ve been training it this way for over 60 years.

  7. Na

    I drink two cups of water when I get up in the morning and the eat a banana several minutes afterwards. I have the same results as described with the coffee. I then take a walks and drink two cups of coffee on my return. No additional bathroom visit. Maybe it is just the liquid??

  8. Karen
    Lakeport, CA

    For 5 decades I have been drinking coffee with caffeine as soon as I get up in the morning. 15 minutes later I am, without fail, defecating. It’s feels great to let that load go, so regularly!

  9. Tony
    NSW, Australia

    I get the same effect from my habit of drinking 2 cups of tea (various blends) every morning. I think it’s the warm water.

  10. Debbie
    Plano, Tx.

    I get the same results with my morning coffee, but it could be just the relaxation effect because I sit and drink it slowly while I read and wake up. I also have to “go” if I sit at the piano and play a while, or if I call and talk to my mother on the phone. The opposite happens when I’m on vacation….can’t always find a relaxing time to go. When I was a teenager before I drank coffee the same thing used to happen after drinking a Dr. Pepper. So the rumor back then was that Dr. Pepper had prune juice in it.

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