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...
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) Um...you 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.
Müller-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