Bad science writing of the day: your gut bacteria make you crave chocolate

I’ve written a post or two (or a dozen) discussing science journalism–the good, the bad, and, mostly (because they’re the most fun), the ugly. There was this story about how blondes “evolved to win cavemen’s hearts.” Or this one that completely omitted the name of the pathogen they were writing about. Or this one, where a missing “of” completely changed the results being discussed.

I ran across another glaring example yesterday, dealing interestingly enough with one of my favorite topics: chocolate, and bringing in an “omics” prospective to it.

The news story covered a recent article in the Journal of Proteome Research. The investigators grouped study subjects according to their answers on a diet questionnaire, labeling them either “chocolate desiring” or “chocolate indifferent.” They then fed them either bread or chocolate on day 2 of the experiment, sampled blood and urine, switched the food they received on day 4, and sampled again.

What they found was that, irrespective of the food they were given (bread or chocolate), the “chocolate indifferent” group had a different “metabonomes” (overall indicators of metabolism) than those who craved chocolate, and they attribute this in large part to potential differences in the microflora of the gut between cravers and those who were more neutral on the chocolate issue. This isn’t that awful surprising; love of chocolate could certainly be one way to differentiate groups of people who have, overall, markedly different dietary habits. Perhaps those who don’t care about chocolate eat less junk food overall, or maybe some are lactose-intolerant and avoid dairy. Either way, it wasn’t established in the study that enjoyment of chocolate was really what gave them their final results.

The authors note in their discussion that:

Our observations demonstrate imprinted differences in the gut microbiotal metabolic activities of the individuals that appear to depend on their previous dietary consumption habits…We note that a specific dietary preference appears to influence the functional ecology and biochemistry of the gut in healthy individuals in the sense that excreted metabolites closely reflect the total metabolic activities of the microbiome.

So, diet influences the gut microbiome–again, pretty much expected. Nothing to see here, folks, move along…right?

Until you get to the news story, with a headline that turns the study’s findings on its head, proclaiming that it’s the bacteria that determine your chocolate craving, not the chocolate cravings that determine the composition of the gut ecology.

I know, I know, the journalist probably didn’t write the headline. Nor did they likely add the picture of the woman seductively eating a square of chocolate, with the caption “maybe it’s not your fault after all.”

Ugh.

So let’s look at the story. It does note (way at the bottom) that

…the research did not determine if the bacteria cause the craving or if, early in life, people’s diet changes their bacteria, which then reinforces their food choices.

Sensical, even! Things are looking up, right? Um….

J Bruce German, a professor of food chemistry at the University of California Davis, said the Kochhar research made so much sense that people should have thought of it earlier.

Where did this come from? Which part of the research is he referring to? There isn’t much here that’s all that original, so the “people should have thought of it earlier” comment is just odd and out of place. The original paper was OK, but the oddly thrown-together news story on the research makes this one go down as yet another disaster in science reporting.

Reference

Rezzi et al. 2007. Human metabolic phenotypes link directly to specific dietary preferences in individuals. Journal of Proteome Research. 6:4469-77. Link

Image from http://raisingchildren.net.au/verve/_resources/00008288001-medium_feeding_toddler.jpg

Comments

#1 Astroprof
November 6, 2007

Very good posting.

I have written several postings about bad science writing. Often science journalism in the mass media is incomplete, inaccurate, or just plain out of date. Part of the problem, I think, is that the majority of “science journalists” have absolutely no science background whatsoever. These were the people who avoided science and math classes in college. They majored in journalism, with the idea that anyone can write about something without knowing what they are writing about.

Now, in all honestly, there are some science reporters who are very good, and they do an excellent job. But most news outlets have either few such reporters (or none). A fairly large portion of the news in modern technologically advanced society involves science and technology topics. Yet, there seems little effort to get that right. As far off the mark as science reporting seems to be, you wonder if you can trust anything that they write.
#2 Matt Penfold
November 6, 2007

I am little bit confused by your mention of lactose intolerance as being a reason people do not eat chocolate. Whilst some chocolate does contain milk much does not.
#3 Tara C. Smith
November 6, 2007

Matt,

True. I guess that reveals my own bias for milk chocolate. The point was, though, that there are a myriad of different reasons why people may eat chocolate (or not)–and all of those could potentially have effects on the composition of gut flora, and on the metabolites you’d detect using methods like they did in the paper.
#4 Dan
November 6, 2007

This is the most ironic joke I’ve ever seen in my life.

Tara “bad science” Smith doing her best to project onto others what she does so well herself, namely bad science writing.

I can hardly wait for the day when Tara, Moore and other noteworthy among the AIDS-promoting goon squad get the public humiliation that’s long overdue for them for pushing deadly dogma and poisons (oh, and the loss of their jobs and “status” as “scientists” too!).

Tara, you’re one cruel joke.
#5 John Marley
November 6, 2007

Dan scores +70 points on the Crackpot Index (#36)
#6 Dan
November 6, 2007

Thank you, thank you very much, John.

It’s an honor I’ll remember for as long as I can.
#7 jen_m
November 6, 2007

Are you sure you mean “ironic”, Dan? “Irony” is used to describe a substantive and illustrative incongruity between events and their description, or between expected and actual outcomes. The distinction between one who writes about science badly and one who writes about bad science isn’t ironic. Neither is the contrast between one who writes about bad science and one who is a writer and a bad scientist.

I’m not sure which you were going for, there, although I certainly got the point that you don’t care for Dr. Smith or her writing. Maybe next time you should stick with something simpler, like, “Ha ha u suk.”
#8 Chris
November 6, 2007

Just an observation, but it seems like every post I read, along with the subsequent comments section, contains A LOT of Dan types commenting in ways that have nothing to do with the subject of the post?
Is it my imagination or is this the usual insanity you must put up with here?

Well, back to topic, I agree with the unfortunate prevalence that bad science writing seems to enjoy in the media. I was born with cystic fibrosis and remember during high school when all the mainstream media outlets were publishing stories about how we were only five to ten years away from a revolutionary gene therapy “cure” for cystic fibrosis.
I graduated from high school in 1990 and tried to explain to people then that the stories were largely exagerated if not downright false. I was scientifically literate enough to know better, but a lot of my family and friends were not. They still don’t understand what happened.
Unfortunately, this is a problem that has been around for awhile and probably will continue to plague us for the foreseeable future.
#9 more of a techie
November 6, 2007

Bad journalism is effective – the “bacteria make you crave chocolate” idea was picked up pretty widely.
#10 jen_m
November 6, 2007

I keep looking at that adorable child and thinking she has some kind of horrible exanthema, and it takes me a minute to remember, “Nope. Still just chocolate.” Context! It’s important.
#11 Xanthir, FCD
November 6, 2007

@jen_m: I think it’s the jpeg artifacts that do it, because I keep thinking the same thing.
#12 Pat
November 8, 2007

Maybe you’re right about the rash, and she is really an orphan who was forced to eat chocolate in a clinical trial.
#13 pat
November 8, 2007

not the same pat
#14 Jerry D. Harris
November 13, 2007

Yeesh, if there ever was a sad, terrible mutation that needed to be weeded out of the human population, it is “chocolate indifferent” (and, of course, “chocolate hating”)…
#15 Kicker
November 13, 2007

Is it a conflict of interest if the p.i. is employed by the Nestle Institute? In the defense of the journalist, the abstract was phrased such that their interpretation was not wholly unreasonable.