According to Vendomois et al, 2009:

these data highlight signs of hepatorenal toxicity, possibly due to the new pesticides specific to each GM corn.

Monsanto, the manufacturer of two of the studied strains of GM corn, responded, dismissing the article, particularly by criticizing the statistical methods used. Is Monsanto's criticism valid?

Have there been additional studies done that either support or refute the claim that genetically-modified corn has toxic effects?

  • Related: skeptics.stackexchange.com/questions/68/…
    – Sklivvz
    Commented Feb 29, 2012 at 22:13
  • Every time I see an anti-GMO study, the first thing I check is if it was published by Séralini. :/ Not fair, but I'm just sick of arguing against his claims. Commented Jun 28, 2015 at 7:34

3 Answers 3


The simple answer is no.

GM corn has the BT gene that allows lower use of pesticides due to increased or the RR gene that allows the use of glyphosate for weed control. Neither of these alterations have any impacts upon the production of sugars or proteins in the plant. http://en.wikipedia.org/wiki/Genetically_modified_maize http://www.ca.uky.edu/entomology/entfacts/ef130.asp

The problem that can arise is from the pesticides that are now used on the crops and the timing of their application. These pesticides are known to harm mammals and if the dose is high enough can cause problems. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2793308/

Generally though, because you are removing pests and weeds the plants tend to be healthier so they are less impacted by pathogens, thus better for consumption. http://www.acsh.org/factsfears/newsID.962/news_detail.asp

There is an issue with using corn as a feed supplement in animals though. Corn is not a complete food source and is generally low in protein, especially tryptophan. This means that a feed mix is required, not just straight corn meal. http://www.ag.ndsu.edu/pubs/ansci/beef/as1238w.htm

Another issue is that corn can cause Pellagra. This is due to the niacin and B12 being bound in the corn starches and not being released in normal digestion. Tryptophan is also low in corn and can cause Pellagra. http://en.wikipedia.org/wiki/Maize#Pellagra


So the problems often cited with GM corn are actually just problems with corn itself. Neither are harmful, if used correctly in a balanced diet, but pesticide residues are of concern. For more see this: http://onlinelibrary.wiley.com/doi/10.1046/j.0960-7412.2002.001607.x/full

  • 1
    The simple answer is no., to "Have their been additional studies done that either support or refute the claim that genetically-modified corn has toxic effects?", or to "Is GM corn toxic?"?
    – gerrit
    Commented Jan 16, 2013 at 21:57
  • 1
    The ACSH source claims Studies Indicate GM Crops Are Safer and Healthier, but last time ACSH reported their funding, they were co-funded by what are now GMO companies. Currently they are not open about their funding at all. Therefore, their independence cannot be established. Can you back up the claim by research where all funding sources are open and independent?
    – gerrit
    Commented Jan 16, 2013 at 22:06
  • 2
    Gerrit - Of course there is plenty of independent data. gmopundit.blogspot.com/ regularly publishes the science on GMO. But that is beside the point, the underlying mechanism of the Bt is not one that works on humans (it is even sprayed in organic farms). We don't have an alkaline stomach to activate the chemical (ditto some insects it doesn't impact either) which means it can't do anything. So the concerns are completely misplaced. Commented Jan 31, 2013 at 10:55
  • 1
    @Sancho I’ve rolled back your edit – it placed undue emphasis on a dodgy hypothesis and completely changed the focus, and thus the statement, of the answer. Commented Aug 23, 2013 at 10:29

We don't know the long term effects that it might have. Feeding studies are generally 90 days long (and most are done by Monsanto, if you trust in the first place).

You also can't simply look at the specific protein produced by the transgene, as introducing a transgene affects the entire phenotype.

Monitoring the pattern of gene expression using microarray technology showed that mRNA levels for 5% of the genes were significantly upregulated or downregulated. Recent studies in transgenic plants showed that the over-expression of a gene involved in pectin synthesis had no effect in tobacco, but caused major structural changes and premature leaf shedding in apple trees [4]. Although these sorts of unpredicted changes in gene expression and function are frequently observed, they have received very little attention. Furthermore, they are not unexpected. The maintenance of a specific cell phenotype involves a very precise balancing act of gene regulation, and any perturbation might be expected to change the overall patterns of gene expression. The problem, as with secondary modifications, is that there is currently no way to predict the resultant changes in protein synthesis."

- Source: Commentary, A different perspective on GM food, David Schubert, Nature Biotechnology 20, 969 (2002) doi:10.1038/nbt1002-969

  • 2
    Please reference your claims that feeding studies are only 90 days long, that they are mostly done by Monsanto and that these are the only way we know about the potential effects.
    – Oddthinking
    Commented Aug 7, 2013 at 14:33
  • The Nature Biotechnology commentary cited triggered a number of disagreeing responses) from the scientific community (which in turn had their conflicts of interest challenged.)
    – Oddthinking
    Commented Aug 7, 2013 at 14:44
  • not related at all to the claim
    – jwenting
    Commented Aug 8, 2013 at 5:55

The simple answer is there is no simple answer. It is not appropriate to unequivocally say "no".

The FDA has stated they are not in the business of policing; rather, they put the onus on the seed corporations.

One only needs to look at history to have some serious questions and concerns. Sure genetic engineering hasn't been around very long so one would need to look at the biggest players in the Genetic Engineering Industry. Monsanto & Dow Chemical two chemical companies with an awful track record.

Yes Monsanto IS a big part of GE Food and wields power and influence like Big Tobacco in the 1970s. They do patent seeds and they now own an estimated 25% of the world seeds due to acquisitions. If you don't know about Monsanto's history check out the Monsanto Controls Your Diet article in Salon Magazine's April 2013 issue. Since 1901 they have been making chemicals that poison. Here is a link to the latest study showing a link of GMO food to leukemia

Yes, each study such as this is refuted by 100 Monsanto, Sygenta, etc. supported/funded studies. It is tough to put trust into studies from Univ. of Florida for instance that receives so much from Sygenta. I do not consider any such studies objective. For decades the tobacco industry did the same thing.

Whenever something is so one-sided (and the power and future profits are on that side) I often find myself skeptical. I am by no means against genetic engineering.

  • 2
    Welcome to Skeptics. This currently reads like a rant, not an evidence-based answer. Please provide references to support your claims that the FDA said they don't police, Monsanto is part of GE food, Florida is receiving enough funding to be tarnished... I am going to clean up some of your more off-topic wanderings.
    – Oddthinking
    Commented Aug 19, 2013 at 5:15
  • 3
    Your argument appears to be "Monsanto is evil. I don't trust any scientists who tell me otherwise. Therefore GM corn is unsafe." This seems to be an unfalsifiable position, and therefore not scientific. What would you accept as evidence that GM corn is safe? If there is no way you could be convinced, you are not applying skepticism.
    – Oddthinking
    Commented Aug 19, 2013 at 5:22
  • 4
    I did not read the Salon article because you said it explained Monsanto's history. It may prove that Monsanto executive sweeten their coffee with the tears of baby orphans; that doesn't have any bearing on the question whether GM corn is toxic. Arguing otherwise is an "ad hominem fallacy". It might well cause you to spend more effort on checking the claims before accepting them, but it isn't an answer in itself.
    – Oddthinking
    Commented Aug 19, 2013 at 8:34
  • 2
    It isn't a case of having my mind made up nor band-wagons. It is a case of requiring evidence - not name-calling, not speculation from history, not poisoning the well, but scientific evidence - before reaching a decision.
    – Oddthinking
    Commented Aug 19, 2013 at 14:00
  • 1
    @Charlie Brown: "Prove Monsanto has a strict policy of selling toxic things?" That sounds completely absurd. Not more than saying that GM crop are toxic just because they are produced by Monsanto. Please provide biological proof that they are toxic. The economical strategy of a company does not have anything to do with the toxicity of a product.
    – nico
    Commented Aug 19, 2013 at 16:06

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