GMO study is pseudoscience

I abhor the exploitative practices of Monsanto and companies like it. But truth is more important than politics, and I am always going to speak out when I see false information being touted as “science” to further an agenda.

I wanted to make this clear because I seem be writing a lot about the misrepresentation of GMOs as being harmful to your health. This article (“GMO feed turns pig stomachs to mush”) is by Natural News, which is emphatically NOT a scientific publication. It’s a site with a definite bias, and implies that people who disagree (I guess that means me?) are “paid online trolls, on-the-take ‘scientists.'”*

Natural News is a complete goofball pseudoscience website, but could the study they cite (Carman et al. 2013: “A long-term toxicology study on pigs fed a combined genetically modified (GM) soy and GM maize diet.”) be the first legitimate evidence that GMOs are harmful to health?

It’s published in the peer-reviewed Journal of Organic Systems, which I’m not familiar with, so I looked it up on PubMed, a government database of major journals:
Screen Shot 2013-07-17 at 12.39.17 PM

Not being indexed on PubMed isn’t necessarily a sign that a journal is fraudulent, but it’s definitely a warning sign that it’s not a journal of any significance or influence. Wouldn’t a find of this magnitude, purportedly overturning the ‘dogma’ of GMO safety, be published in a major journal? (Answer: it would, if it were legitimate).

The big question motivating this research is: Are GM crops safe for mammals to eat?
Carman et al. assessed the effects of a GM diet on pigs (84 fed GM foods, 84 controls) for 22.7 weeks. Blood draws to assess toxicity were performed two days prior to slaughter; after slaughter the organs were assessed by veterinarians.

The authors reported finding:

-“No difference in disease status of organs between the two groups of pigs” except for inflammation.
-Inflammation was found in both groups of pigs.
-Non-GM fed pigs showed more inflation in the “mild” and “moderate” range.
-GM fed pigs showed more inflammation in the “severe” category.
-No statistically significant difference between the two groups was observed in blood toxicity levels measured.

Carman et al. concluded that “Pigs fed a GMO diet exhibited heavier uteri and a higher rate of severe stomach inflammation than pigs fed a comparable non-GMO diet.”

Looking with a reviewer’s eye, right away I noticed that the authors are cherry-picking studies to support their intended outcomes. They don’t mention the serious methodological flaws that invalidate the Séralini study, nor did they reference all the studies showing the safety of GM foods (eg here and here). If I were a reviewer, I’d send the paper back to the authors to revise based on this alone. Understand that it’s important to thoroughly review all the literature, not just that which supports your position, and note all areas of disagreement. To do otherwise in a scientific publication is biased and misleading.

In addition to the literature review, there are methodological flaws. First of all, the authors only show stomachs from four selected pigs out of the 168 study pigs, in this figure:

Carman et al. 2013 Figure 1
Carman et al. 2013 Figure 1

Why is this a problem? It’s quite possible that they’re picking the best stomachs of the control group and the worst stomachs of the experimental group to show. This is a very common practice with bad papers–it would be more appropriate to upload images of ALL the stomachs as online supplementary data, or at least show many more examples. Four is simply too few to be honestly representative of all the data.

As for their claims of GM food causing inflammation, they haven’t followed the standard methods for this type of research and this may have introduced some series biases into their analyses. You can’t detect inflammation based on the color of the stomach lining, as the authors did:

“it was incorrect for the researchers to conclude that one group had more stomach inflammation than the other group because the researchers did not examine stomach inflammation. They did a visual scoring of the colour of the lining of the stomach of pigs at the abattoir and misinterpreted redness to indicate evidence of inflammation. It does not. They would have had to take a tissue sample and prepare histological slides and examine these samples for evidence of inflammatory response such as white blood cell infiltration and other changes to determine if there was inflammation. There is no relationship between the colour of the stomach in the dead, bled-out pig at a slaughter plant and inflammation. The researchers should have included a veterinary pathologist on their team and this mistake would not have happened. They found no difference between the two experimental groups in pathology that can be determined by gross inspection.”–Robert Friendship, quoted in Terry Daynard’s blog

There are some serious problems with the methods the authors used to analyze the data as well. Statistical analyses are crucial in scientific research; they’re only way of separating out credible differences from those due to chance alone. Put simply, authors used inappropriate statistical methods for analyzing this type of data.

As Mark Lynas puts it (emphasis mine):

You can immediately see how the data is all over the place from the previous results, which also rule out any causal mechanism with GMO feed – if GMO feed is causing the severe inflammation, why is the non-GMO feed causing far more mild to moderate inflammation? It’s clearly just chance, and all the pigs are not doing well and suffering stomach problems: about 60% of both sets had stomach erosion.

Here is an explanation of what they did wrong, and a re-analysis of the data using more appropriate methods.

Even if we pretend that the authors conducted the study using appropriate measures of inflammation and appropriate statistical methods, you still can’t conclude from these data that GM food causes inflammation.

The ONLY statistically significant difference is in the category of ‘severe inflammation’; there are actually more total cases of inflammation among the non-GM fed pigs. There’s no dose-dependent effect.

So this study still doesn’t support hysterical comments made by Natural News and other anti-GMO activists about adverse health effects caused by GMOs. The reason these studies are so badly designed is that they aim from the beginning to obtain a particular result. Not only is this practice incompatible with conducting rigorous science, it also violates all basic standards of care for ethical animal research:

My judgement is that, as with Seralini, this study subjects animals to inhumanely poor conditions resulting in health impacts which can then be data-mined to present ‘evidence’ against GMO feeds. Most damning of all, close to 60% of both sets of pigs were suffering from pneumonia at the time of slaughter – another classic indicator of bad husbandry. Had they not been slaughtered, all these pigs might well have died quickly anyway. No conclusions can be drawn from this study, except for one – that there should be tighter controls on experiments performed on animals by anti-biotech campaigners, for the sake of animal welfare. —Mark Lynas

Are you comfortable with shoddy and ethically questionable research being conducted to prove your “side” right?

It’s particularly easy to accept information touted as “scientific” if it happens to fit with what you believe anyway. It is very, very hard to accept that what you believe might be wrong when evidence shows it. But you must. If I discover tomorrow that a result or interpretation I’ve published is incorrect, I will definitely feel embarrassed, but I will try not to stubbornly insist that I’m right in the face of convincing evidence. If I did, my work would be based on the tools of faith, not science. There’s no difference when approaching contentious political/social issues; you can’t claim the mantle of scientific research when you don’t follow scientific methods. I’m always in favor of MORE research on this subject. But if you’re a GMO critic, I strongly suggest that you demand that researchers follow the accepted and standard practices of the field in their data collection and analysis methods, as well as the highest ethical standards when it comes to animal research.

I want to close by reiterating that while there are some extremely valid criticisms of Monsanto and similar corporations, the best research out there does not show GM food to be unsafe. Remember:

“If it disagrees with experiment, it’s wrong.”

No matter how you might wish it to be otherwise.


*In case it’s not obvious, I don’t make a dime from any corporation, least of all Monsanto.

References and further reading:
“A long-term toxicology study on pigs fed a combined genetically modified (GM) soy and GM maize diet.” Judy A. Carman, Howard R. Vlieger, Larry J. VerSteeg, Verlyn E.Sneller, Garth W. Robinson, Catherine A. Clinch-Jones, Julie I. Haynes, and John W. Edwards. Journal of Organic Systems, 8(1), 2013

Published criticism of the Séralini study (behind a paywall, unfortunately, but if you’re really eager to read it, get in touch)

Here are a few other perspectives on the methodological flaws in this study if you’d like to learn more:

20 thoughts on “GMO study is pseudoscience

  1. Lee Gillaspie July 21, 2013 / 9:25 am

    this is just deceitful propaganda, natural news is pure truth

      • Sullivanthepoop August 29, 2013 / 8:04 am

        Because it’s opposite day.

  2. Justin Siemaszko August 19, 2013 / 8:43 am

    Thank you for your thoughtful writings. It’s nice to know that at least a few rational people drifting around the world & internet.

  3. abby hummel August 20, 2013 / 9:51 pm

    Jennifer, I think you are on the right track here. To be honest, I can’t speak the technical lingo of most scientific papers. I took the arts track in my undergrad, majoring in Music and an interdisciplinary Western Religious Studies program. I loved it; that’s my niche. My interest in this topic comes because my husband is a few months away from earning his doctorate in plant pathology in a very reputable lab and has several papers published in reputable peer-reviewed journals. We have been astounded by how rudely people have spoken to us about GMO crops and plant genome engineering knowing full well this is his profession. On several occasions we have invited new friends over to our house, apparently the sort of people who see nothing wrong with eating food I have prepared for them while telling my husband his life work is giving me IBS or making our grandparents more likely to die from cancer. Mostly, when people try to monopolize the GMO conversations in their favor, I just tell them we are not interested in continuing that discussion together until they have earned an advanced degree in plant genomics or molecular biology, at which time I will gladly brew them another pot of coffee and welcome them back.

    A few instances of poor manners aside, I don’t think science is on the side of the anti-GMO group. It’s just affluent narcissism, that is, people in the first world who have a choice about what to eat getting really excited about things they don’t actually understand because they read an article about it somewhere. I’m with you that from what I can tell so far, Monsanto has some shady business practices, but the anti-GMO research just isn’t scientifically sound enough to exclude these crops from the food supply. I think you’ve explained it well here, much better than I could.

    I started this comment with the caveat that I’m no scientist. I’m not able to contribute to scholarly discussions until we’re talking about Classical Latin, tonal theory, the ethics of economics, or the role of death in dystopian literature. For the purposes of the GMO discussions in American culture, I don’t think it matters. I can’t really read the scientific papers? So what. Neither can 98% of the people posting anti-GMO propaganda all over my facebook newsfeed. (The other 2% are friends and colleagues from my husband’s lab.) So, much like what you say in your vaccines post, the professionals actually know more about GMOs than un-reviewed “articles” from Google University. Shocker!

    • Jennifer Raff October 8, 2013 / 3:24 pm

      Thank you for your thoughtful comment and kind words (and apologies for the late reply–I got busy with comments on my vaccines article, as you might imagine!).

      I firmly believe that anyone can grasp the basics of a scientific article, it just takes quite a bit of practice. But perhaps it’s more useful to find a good set of criteria by which to judge secondary sources? I’m thinking hard about how to do this (beyond the usual “this is science, this is pseudo-science” framing).

  4. JohnS August 22, 2013 / 6:27 am

    Great article! There are many legitimate problems with GMOs…but I suspect none of them, at this point, have to do with them being bad to eat! Reduced biodiversity, potential propagation of disease resistance, ownership of DNA, penalizing nearby farmers for patented seeds dispersing naturally to other property without a license, etc. But food is just chemistry.

    • Sullivanthepoop August 29, 2013 / 8:08 am

      I know, those practices make me sick. You cannot just blame Monsanto though. Why does the US government encourage this behavior? Other countries often throw out Monsanto’s ridiculous lawsuits. Think about this, Monsanto has been involved in more lawsuits than any other company, usually as the plaintiff.

  5. Bobo August 27, 2013 / 5:11 pm

    In the future, you should be more careful to specify that PubMed primarily serves up biomed and other papers from certain life sciences. A physical sciences journal not being indexed by PubMed is not necessarily a tell that it is a bad journal.

  6. gguay August 28, 2013 / 7:36 am

    Great analysis — have you thought about a book where you analyze other articles, for use as a “how-to” guide that could supplement a college upper-level class in research methods? (As an occasional instructor of such classes, this could be a boon…)

    • Anonymous October 8, 2013 / 3:20 pm

      oh my oh my! We undergraduates would love this! At least, the particularly nerdy ones who want to read, write, and understand scientific research. Truly, this would be better than Diana Hacker.

      • Jennifer Raff October 8, 2013 / 3:27 pm

        Interesting idea! I don’t know if I could find a publisher who would be interested in such a book, but maybe….?
        In the meantime, it’s actually (spoiler alert!) one of the directions in which I’d like to take this blog. Any suggestions for papers to review would be welcome! 🙂

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  8. d September 11, 2014 / 11:18 pm

    Nice article. It seems like the genetically modified food pseudoscience is on the rise. It’s going to be more and more of a conspiracy theorist type topic and thus it is nice to see an article like this…

  9. David September 18, 2014 / 3:10 pm

    Hi Jennifer,

    Good article but I got a kick out of the fact that you felt it necessary to defend yourself by starting with: “I abhor the exploitative practices of Monsanto and companies like it.” Yet never identify what those “exploitative” practices are. I could be wrong but I strongly suspect that you’ve bought into anti-Monsanto misinformation put forth by the anti-GMO movement. There is no lie they won’t engage in when it comes to Monsanto (i.e. “they sue you when your crops get cross pollinated”), who BTW, is nowhere near as large nor dominant as they would have you believe.

    Anyhow, if you have time I’d appreciate you stating in the comments what those exploitative practices are.



  10. Merryl January 12, 2015 / 5:27 pm

    I also abhor the practices of Monsanto, the makers of Agent Orange!
    If people choose to ingest foods that are genetically modified, or sprayed with pesticides that should be their prerogative.
    I and many others choose organically grown foods. I should have the right to know what is in my food, hence labels.
    I should also be able to decide if I want organically grown foods. Whether you think they are the same, is neither here nor there. I cannot understand the large food producers having a problem with labels.Are they afraid that they won’t make enough money?
    I do understand that fear tactics and false information hurts everyone, but transparency to the consumer is a win/win situation.
    One subject that hasn’t been addressed is how GMO crops hurt pollinating insects, and bats. Why is it that given a choice, squirrels and birds would rather consume non-GMO corn?
    Until further studies have been done, we need to question GMO safety. We certainly can’t leave it up to Monsanto, Dow Chemical, or Bayer to tell us what is in our best interest…now that would be (psycho) science.
    Mrs. Merryl F. Goldman

  11. JJPeregrine (@JJPeregrine) August 18, 2016 / 11:12 am

    Aside from the genetically engineered crop trade, after Monsanto’s decades long efforts to whitewash the toxic effects of Agent Orange, any sane society would run them out of town on a rail.

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