Friday Weird Science: So, how would you say your poop FEELS today?

Aug 13 2010 Published by under Friday Weird Science

The following is my entry for the newly created Carnal Carnival, a blog carnival started by Jason (of The Thoughtful Animal and Child's Play) and our dear blogfather Bora. Sci is a little upset she didn't think of it first. This will be a carnival covered the weird and odd and, if possible, the completely gross in science!

This month's topic? Well, if you're gonna get into it, you might as well GET IN. This month's topic? POOP! Poop, fecal matter, stool, spoor, shite, crap, or doody.

Obviously I was totally excited about this and HAD to find a good article on poop. AND I DID.

So. What do the following foods have in common?





Hmmm, me thinks one of these things is not like the other ones... Muller-Lissnera et al. "The perceived effect of various foods and beverages on stool consistency" European Journal of Gastroenterology & Hepatology 2005

So apparently, when the Rome Committee on Functional Bowel Disorders gets together, they spend a lot of time having scholarly debates on the subject of foods. Which foods are constipating, and which foods are not? Inquiring minds (and inquiring bowels) NEED TO KNOW. And apparently, being the Rome Committee on Functional Bowel Disorders, they decided that what they really needed to do was a SURVEY. Of Germans. Because what people think about which foods are constipating apparently varies highly across countries.

So they surveyed 200 people who had normal bowel function, 122 people who suffered constipation, and 766 people who were diagnosed with Irritable Bowel Syndrome with constipation as the major symptom. No word on why the IBS patients were really over-represented. Apparently all the constipating patients said they were constipated (also, they want you know that large cat is large), and 3.5% of the control group also complained on constipation (which made me wonder why they were in the control group at all). Oh also, the 200 healthy people were family and friends of the personnel in the hospital. Because they wanted to make very sure they were unbiased.

So anyway. The questionnaire asked the subjects to list foods that made them constipated, and then asked about the following items: coffee, black tea, chocolate, beer, wine, cigarettes, prunes and bananas.

Here's what they got, graphed for your pleasure.


If the bars lean to the right, you get softer stool, if they head to the left, you get harder stool. You can see that beer (who hasn't heard of the beer sh*ts?), wine, coffee, prunes, and cigarettes made you need to go, while bananas, black tea, and chocolate stopped you up. When asked to list other foods, everyone listed white bread as being very constipatory.

They researchers also noted that the subjects who didn't complain of suffering from constipation were much more likely to report super loose stool (does anyone else have a hard time writing "diarrhea"? I just have the worst time SPELLING it!).

Now, you might think the scientists would conclude these foods cause constipation. They did NOT conclude that, and I'm very glad they didn't, because I would have had to be very snarky. No, they concluded that people PERCEIVE foods like white bread, chocolate, and bananas as causing constipation, and perceive foods like prunes as causing a looser stool.

What amused Sci very much was how the authors then spent a full half of the discussion talking about the potential constipating effects of chocolate, including possible interactions with the ovulatory phase in women.

Now, first some points:
1) Why the heck are the IBS patients so over-represented?
2) recruited your family and friends to take this questionnaire, and you published this in a journal as unbiased? Really?
3) You keep saying your results show chocolate is constipatory. I do not think this means what you think it means.

Sci will be honest. I have NEVER heard of chocolate causing constipation. Cheese? Absolutely. White bread? Sure! Bananas, yup. Chocolate? Never. Black tea?! Now you're sh**ting me, yes? (ok, maybe I said that just so I could say something about "you're sh**ting me"). I mean, surely we all know that caffeine acts as a muscle relaxant in the bowel. Further, studies have shown that black tea specifically makes poop softer. So I'm thinking this really is a case where people BELIEVE that black tea causes constipation, where in reality it should be flipped over and right over there with coffee on the right.

Ad for nicotine, I'm not really sure on this one. Nicotine has been shown to be helpful in some aspects of bowel disease, but really UNhelpful in others. OTOH, many people report taking a nice comfy crap after the morning cigarette, so who knows.

But here's the main point: this study does NOTHING to prove that any of the above items causes constipation or not. It merely says what people THINK causes constipation. Maybe people from Germany don't think cheese causes constipation and people from the US do? Ideas about what causes constipation can come from lots of places. For example, I'm sure EVERYONE has heard that fiber is good for your poops, and of course we know that whole grain breads and prunes contain loads of fiber, and obviously white bread DOESN'T. But this doesn't actually mean that white bread in and of itself CAUSES constipation where there is none. And of course this study didn't actually take healthy people, give them a pile of chocolate, and then watch them poop. That's clearly a different study (and I would totally volunteer for that, the chocolate would be worth it!).

And of course you can't discount a possible placebo effect. Maybe someone started a rumor sometime back about black tea causing constipation and now everyone's got it on the brain, whether it's true or not. But belief in something can make you see constipation where there is none, or be a lot more sensitive to your bowel developments than you might otherwise.

So moral of this story? It's possible that if you're worried about being constipated, you should avoid some of the stuff on this list. Not because it actually causes constipation (though some of it might), but because you might BELIEVE it does. Poop psychology.

Mรผller-Lissner SA, Kaatz V, Brandt W, Keller J, & Layer P (2005). The perceived effect of various foods and beverages on stool consistency. European journal of gastroenterology & hepatology, 17 (1), 109-12 PMID: 15647650

17 responses so far

  • Daneel says:

    Hahaha, "comfy crap". Coffee always makes me wanna go. That's also true for bananas. ๐Ÿ™‚

  • Jason Dick says:

    Wouldn't really be much of a surprise to me if peoples' ideas of what does/does not cause constipation (or the opposite) are at large variance with reality, especially when you consider that pretty much the bare minimum time between ingestion of the food and the next bowel movement including that food is ~8 hours (and that generally requires some laxatives), with a typical delay being much longer.

  • Jason G. Goldman says:

    You just won the internet.

  • peggy says:

    The study also doesn't take into account that people rarely eat those foods alone. I suppose some people might live off white bread alone, but my guess is that's pretty rare.

  • Miranda says:

    Not that I have any references at all, but here's an anecdote about chocolate causing constipation! When I was younger, every Easter my parents warned us not to eat too much chocolate in one go or we'd get constipation.

    Of course, I did then eat all my eggs, and got it so bad the whole family came to look at me on the toilet (probably the only reason I remember it at all) before my mum made me eat a whole bowl of stewed prunes.

  • Christina Pikas says:

    Has anyone done a study comparing coffee, tea, and warm water? I say that because my great grandmother used to say that drinking warm water would get you going. Of course being properly hydrated is good anyway.

  • I've found that "the squirts" is a lot easier to spell.

  • becca says:

    I'm pretty sure prunes and bananas work for the indicated purposes. Although I kind of wonder about the impact of dosage and ripeness variables (I remember learning, as a child, that n > 3 bananas is a Bad Idea).

    Babies are great experimental subjects for this (also, Jason, is the minimum transit time ~8h *in adults*, because that seems like too long for an infant? Some... colorful items are pretty distinctive, and I could've sworn 8h was on the long side in that experimental system.)

    I was *flabbergasted* at the results here for coffee. I was pretty sure it has the opposite effect for me.

    Sci- I think our reactions to these studies, and how they disagree with our own perceptions is really funny. Your reaction: "People think differently from me... PSYCHOLOGY!" My reaction: "People poop differently from me... WHAT'S WRONG WITH MY MICROBIOME?!"
    I would really, really , really like to know what % of cross-cultural differences are due to different foods/eating patterns, which are due to different *perceptions*, which are due to different genotypes, and which are due to different microbial populations. There is just SO MUCH that needs to be studied here.

  • Pascale says:

    Iit really cracks me up that you didn't write out the word "shit." There. I did it. In your list of synonyms you failed to include "scat." I'm sure we will be able to come up with other words as time goes on. Where is PhysioProf?

  • scicurious says:

    Sci always blocks out the cussin', in a tiny effort to make it a little more young person/delicate-ears person friendly. But on a poop post it was REALLY hard. ๐Ÿ™‚

    Ooooh yes! Scat. Excrement. Dung. Feculence! Apparently you can also call it Ejectamenta, which sounds hilariously Harry Potter-esque to me. A spell to relieve constipation! Wave your wand with a careful swish and flick, and loudly say "EJECTAMENTA!"

    Also probably very hilarious in magical combat. ๐Ÿ™‚

  • Markus says:

    Just one thing: I am German and I have actually never heard of cheese causing constipation. You might be on to something here. Maybe there's too much of a difference between the cheese consumed here and in the US? From what I've seen cheese plays a more central role in the German diet and that certainly does not include that processed cheese..

  • Jojo says:

    You just totally made my Lego Harry Potter game much, much, much funnier.

  • Asp says:

    It is common belief in Croatia that chocolate causes constipation.

  • stripey_cat says:

    I'd have guessed that caffeine causes constipation, not the reverse, going from my own experience. Possibly the diuretic effect of caffeine can cause you to absorb more water from the stool to compensate, or something. (Certainly dehydration from other causes makes me very constipated.)

    No comment on the chocolate thing - although we can now claim that we're self-medicating diarrhea when we eat a whole bar.

  • Katherine says:

    Hmm, I'd always heard that alcohol tends more towards making people constipated than the reverse, though my personal experience says otherwise.

  • AK says:

    WRT chocolate, IIRC many older types included various types of wax, which might have been responsible for constipation, while the cocoa itself wasn't (OTOH see below). Once the myth gets established, anytime somebody eats chocolate and gets constipated (no matter what else they ate) it reinforces the myth, while when they don't they don't notice.

    As for black tea, I've used caffeine in many forms, and for me coffee probably has the most laxative effect, while NoDoz has probably the least. For me, most types of tea are even less laxative (by caffeine content), which I've always guessed (without checking) was due to the theobromine. Interestingly, a quick check of google shows cocoa also contains theobromine.

    Among my favorite forms of caffeine are Mountain Dew, both normal and diet. They contain equal amounts of caffeine, but the normal also contains sugar and I find it much more laxative. This probably also applies to beer and wine, although the carbohydrates in these drinks are much more complex. I've found that vodka mixed with sugar-free mixes is much less laxative (by alcohol content) than beer, wine, hard cider (Woodchuck) and vodka mixed with sugar-containing mixes.

  • Sam W says:

    WIN for that Harry Potter joke... would make for a funny caption contest as well.

    As for constipation, I guess once again we can see that it's all about a balanced diet. I've never had an issue with any of these food personally.

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