Ask Us Anything About GMOs!

First, how do you respond to the recent study showing leaky gut and other health conditions in pigs over a 22.7 week period (the average length of time spent at a U.S. Piggery)? Please feel free to read through the study material here: Second, what evidence can you provide to counter the information showing an increase in a variety of gastrointestinal diseases coinciding perfectly with the introduction of GM foods in the mid-90s? Finally, is it not factual that what Monsanto and other biotech companies call an increase in crop yield is actually due to other factors, such as replacing diverse fields (full of many different crops) entirely with cotton or wheat and then stating how many more kilos of cotton or wheat are being produced? Is it not common sense that if you plant more your yield will be more? Respectively, how do you feel that places like India are showing that organic gardening produces far more output per square foot than genetically modified crops?

A:Expert Answer

Answer at a Glance:
  • There is no commercialized GMO wheat. The data do not support that the cotton yields are increased only because more seeds are being planted; however, there are data to support the fact that when an equivalent amount of GM cotton seed is planted side by side with an equivalent hybrid of conventional cotton, the overall yield from the GM cotton plant is higher than the conventional hybrid.
  • India does have the largest numbers of organic farmers, but the reason for that could quite easily be the small area that each farmer farms. But it should be noted that no yield data exist to show that the 1 million hectares of India’s 179.9 million hectares of agricultural land that are used for organic agriculture are more productive than genetically modified crops.

Farmers adopt new agricultural technologies because they see benefits like increase in yield, reduction in input costs or overall increase in ease of farming. For example, in India, several reports from researchers both outside India and within various states have documented that the adoption of insect-protected cotton has increased from a few thousand hectares in 2002, when the technology was first approved in India, to 11 million hectares (over 90 percent of the total area where cotton is grown) in 2013 (ISAAA, 2014); this rapid adoption was led by an overall increase in profitability due to higher yields and reduction in pesticide costs (Kathage and Qaim, 2012; Mayee and Chaudhary, 2013).


Kathage and Qaim studied the effects of Bt cotton adoption from 2002 through 2008 and showed that adoption of Bt cotton has increased yields and profits by 24 percent and 50 percent, respectively and the impacts of Bt cotton have been stable over time. Mayee and Chaudhary (2013) recently published their report on the socioeconomic benefits of adoption of Bt cotton in three states — Punjab, Maharashtra and Andhra Pradesh — from 2002 to 2011, and their results showed doubling of yields in all three states in both rain-fed and irrigated conditions. Mayee and Chaudhary also concluded that “Bt technology has decreased pesticide usages, increased cotton productivity and increased farmers’ income and contributed significantly to poverty alleviation.” I also personally heard from cotton farmers in India, when I stayed there in 2010-11, that Bt cotton had significantly improved their lives and they would like to see additional innovative agricultural technologies to help them produce more with fewer inputs.


While I was unable to find any actual data to support your statement that yields of cotton and wheat have increased only because more seeds are planted, it should be noted that while yields of cotton have increased significantly in the last ten years in India, yields of other crops have not decreased but have shown low to moderate increases. I totally agree with you that yield comparisons have to be done by planting fields with a given GM and conventional crop with similar agricultural practices; only then can one make the claim that there is an increase in yield. Please note that the Indian regulations for approval of GM crops require such data to be generated for every new GM event, and that the developer provided the authorities with these data. Meanwhile, farmers base their decision on what to plant every year on the overall potential profits from the crop being planted, so the sustained increase in acreage of cotton in India suggests that most farmers in India are reaping the benefits of Bt cotton.


Please note that while India does have the largest numbers of organic farmers in the world, only 1 million hectares of India’s 179.9 million hectares of agricultural land is used for organic agriculture. Also, the only genetically modified crop that is grown in India is cotton, and, as discussed above, over 90 percent of the farmers grow genetically modified cotton because of higher yields and reduced pesticide use. While I found no comparative studies on organic versus conventional farming in India, a few studies done in the United States and Canada that compared yields for organically grown crops and conventional agriculture showed that yields in conventional agriculture fields were generally higher, sometimes by as much as 25 percent, in most crops (Seufert et al., 2012; Kirchmann et al., 2008; and this blog post by Steve Savage, which evaluated the USDA data). Personally, I strongly believe that farmers should have the right to choose and plant what is most beneficial to them.




  1. ISAAA Brief No. 46, 2014. Global Status of Commercialized Biotech/GM crops.
  2. Kathage and Qaim, 2012. Economic impacts and impact dynamics of Bt cotton in India. PNAS 109, no. 29: 11652-11656.
  3. Mayee and Chaudhary, 2013;
  4. Seufert, V., Ramankutty, N. & Foley, J.A. (2012). “Comparing the Yields of Conventional with Organic Agriculture.” Nature 485: 229-232.
  5. Kirchmann, H., Bergstron, L.; Katterer T.; Andren O.; Andersson R. (2008) “Can Organic Crop Production Feed the World?” In Organic Crop Production – Ambitions and Limitations. Kirchmann and Bergstrom (eds.). Springer. 39-72.
  6. Savage, S. “US Organic Farming: Digging into the Numbers.” Sustaina blog. 

A:Expert Answer

Moderator Note: This question will be answered in two parts. This answer addresses the portions of the question about the pig feeding study and claims that GM crops are connected to gastrointestinal diseases. The rest of the question will be addressed in a separate answer.


Health conditions in Pigs: The study you are referring to is (Carmen et al., 2013) and I have personally been involved in several comprehensive animal health studies like this, in which we collaborated with teams of veterinarians, pathologists, nutritionists, etc.  What I’ve learned from that experience and what I find most revealing about this study is what didn’t happen.  


The first thing that didn’t happen is that pigs were not properly placed in pens.  When animals are administered treatments by pen (i.e. all pigs in a pen are given the same treatment) then the pig is not the experimental unit, the pen is.  They seem to have done a statistical analysis with pig as the experimental unit, which will result in false positives.


The next thing that didn’t happen is leaky gut.  There was nothing measured in the entire study that would be related to or even suggest leaky gut.  What they did “claim” that’s related to the gastrointestinal tract was inflammation of the stomach.  Every first-year med/vet student learns that the signs of inflammation are: dolor (pain), calor (heat), rubor (redness) and tumor (swelling).  The only thing they ‘observed’ was red.  They could have done histopathology to really understand what they ‘saw’, but for some reason they did not do this.  The first thing I noticed  was those stomach pictures.  Pigs are prone to gastric ulcers that are usually located in the cardia region (where the esophagus enters) and are often bloody.  This occurs when pigs are stressed and there was no indication of that.  Furthermore, when they looked at these stomachs, that might have been red based on the way they euthanized the pigs, they assigned them to four categories and then they did stats on two of the categories and left out the other two. But the pigs had four possible outcomes, not two.  If you appropriately analyze the full data set and assume pig is the experimental unit (like they wrongly did), there is no effect of treatment.


They also reported that there was an enlargement of the uterus and that when they cut one open clear fluid oozed out.  That sounds like it came from a pig in estrus (heat).  This would have been simple to verify because while they were looking at the uterus they could have found a wealth of information by looking at the ovaries that are found just slightly forward of the uterus.  By looking at ovarian structures you can tell if they are pre-puberal, post-puberal, in estrus, post estrus or pregnant.  You can see that this is a lot of information that was also not included – and, unlike histology, it doesn’t even cost money to obtain.  In our health studies, gross lesions are almost always collected for histopathology. 


If you are wondering why these items are not discussed in a peer-reviewed paper, look at the editorial board of this journal and you won’t see animal scientists, toxicologists or veterinarians.  It really would have benefited by a peer review of a top-tier animal science journal.


The final thing that did not happen is a change in growth rate (according to Carmen).  I’ve learned in 35 years of experience that stressed or sick animals do not grow as well as healthy animals, suggesting that the health of these pigs was similar to that of the control pigs.  The goal for swine producers is well known, “happy as a pig in…”. You get the picture.


Gastrointestinal Diseases: The ‘association’ between gastrointestinal diseases and glyphosate is a classic example of association vs. cause & effect. This was well illustrated by the blog post written shortly afterwards (that showed another perfect correlation between consumption of organic food and autism. For the record, I don’t buy that one either.  In fact, it is unfortunate when these types of associations distract from making real progress on serious diseases like autism and celiac disease.  One website posted many examples of associations and these were the result of computer programs that search thousands of databases looking for associations.  The associations of things like divorce rate with margarine consumption are not obvious to people so they are more easily dismissed.  But the associations that meet someone’s preconceived expectations become more believable.   Your phrase “coinciding perfectly” is actually a red flag.  In epidemiology there is recognition of lags that occur in data.  Most of our critics think we need to move slowly on new technologies and want long-term multi-generational studies. These plots show no indication of lag.  So which is it - longer studies or instantaneous cause and effect?  


Recently, in July, Alison Van Eenennaam, who has answered questions on this site, gave a presentation at the Annual Meeting of the American Society of Animal Sciences that showed animal performance measurements for more than 100 billion animals in the US that have gotten diets with GM feeds, some of which are whole grains with no processing other than grinding. Her conclusions are that there are no indications that animal health and productivity have been affected by GM crops. This was published as an “Invited Review” paper in the October Issue of the Journal of Animal Science.  

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