Guest Post: Study: Genetically Modified Corn Increases Body Weight in Rats

We previously reported:

Many crops in the U.S. are now genetically modified. For example, 93 percent of soybeans grown in the US are genetically engineered, as are:

Some allege that Roundup kills healthy gut bacteria, and that genetically modified crops cause other health problems.

Many people claim that genetically modified (GM) foods increase obesity:


But is there any evidence for that claim?

One study implies that there might be.

Scientists tested GM corn at Monsanto laboratories, and found that the GMs increase body weight in rats. Specifically, a paper published in the International Journal of Biological Sciences reported in 2009:

We present for the first time a comparative analysis of blood and organ system data from trials with rats fed three main commercialized genetically modified (GM) maize (NK 603, MON 810, MON 863), which are present in food and feed in the world.


The three animal feeding studies were conducted in two different laboratories and at two different dates; at Monsanto (Missouri, USA) for NK 603 and MON 810 (June 7, 2000) and at Covance Laboratories Inc. (Virginia, USA) for MON 863 (March 14, 2001) on behalf of Monsanto.


Crude and relative liver weights are also affected at the end of the maximal (33%) GM maize feeding level as well as that of the heart which for corresponding parameters to a comparable extent, showed up to an 11% weight increase.


Additional statistically significant differences include … higher … overall body (3.7%) weight


Several parameters indicate increases in circulating glucose and triglyceride levels, with liver function parameters disrupted together with a slight increase in total body weight. This physiological state is indicative of a pre-diabetic profile.


Our data strongly suggests that these GM maize varieties induce a state of hepatorenal [i.e. kidney and liver] toxicity.


This can be due to the new pesticides (herbicide or insecticide) present specifically in each type of GM maize, although unintended metabolic effects due to the mutagenic properties of the GM transformation process cannot be excluded. All three GM maize varieties contain a distinctly different pesticide residue associated with their particular GM event (glyphosate and AMPA in NK 603, modified Cry1Ab in MON 810, modified Cry3Bb1 in MON 863). These substances have never before been an integral part of the human or animal diet and therefore their health consequences for those who consume them, especially over long time periods are currently unknown.

Remember that some GM crops are engineered to have the plants produce their own pesticides. Some pesticides can cause obesity. And – contrary to pesticide industry claims – the pesticides are not somehow magically destroyed before making it into our bloodstream.

Many past studies have also shown health and environmental problems from GM foods as well.

Indeed, even animals are getting fatter … which points to something in the environment.

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  1. Maju

    A trick with these GMOs, being intellectual property, is that you can’t do experiments (in principle) unless you purchase them and, if you purchase them, you are forced to sign a document renouncing to do any experiments without the company’s authorization.

    So most of the research is simply non-existent (because governments do not dare to confront the GMO mafias either but rather promote their interests).

    (Not posting links because last time I did my comment stood for days in moderation limbo – not sure if it was ever approved: I lost track).

  2. Curtis

    The world just needs for the chemists to inadvertently reduce fertility with their pesticides. They may have already done so but don’t know it yet.

  3. Jardinero1

    The problem is really with corn, not GM corn. You shouldn’t eat corn or corn products if you don’t want inflamed intestines, high cholesteral, obesity, heart disease and diabetes.

    1. Stephanie

      That’s silly. It’s been a staple food since prehistoric times in North, Central, and South America. I don’t think people were regularly dying from high cholesterol, diabetes, and heart disease back in those days…

      1. Jardinero1

        For most of human evolutionary history, we consumed meat, fruits, vegetables, nuts and roots. Humans only began consuming grain six to ten thousand years ago which is only an evolutionary blink of the eye in time. Our guts are not adapted to eating corn or grains. In fact, few animals except birds metabolize grains well.

        1. Jardinero1

          Also, “back in those days”, the average lifespan was much shorter than it is today. You did not live long enough to suffer the damage that grains cause. Eating grain is similar to smoking in the way it damages you. You have to do it for years, even decades before the harmful effects become apparent.

      2. Jordan M

        We ate seeds as well, which is what grains are. And we didn’t just start eating them in the past ten thousand years. Rather we started cultivating them around that time since seeds represent a great form of food storage. There are wild grains that we did, and still do, consume, something that obviously began before we started practicing agriculture. Human are omnivores; we can handle a wider range of foods than you credit us with.
        ps. I guess a vast majority of rodents are a type of bird given how well they handle their grains. Seeds, including the seeds of grain, are eaten by a wide range of animals, not just birds!

        1. Jardinero1

          Prior to the advent of field agriculture, grain was the tiniest part of the human diet. Today, wheat, corn and corn by-products are the largest part of a modern american diet, making up nearly three fourths of most American’s dietary intake. It’s unprecedented and the primary reason for the high incidence of obesity, diabetes and heart disease.

      3. James Cole

        Also, back in the old days, corn was nothing like what we know as corn now–it was smaller and had less simple carbohydrates, more fiber and complex carbohydrates. Google “heirloom corn” and you’ll see what I mean.
        Altogether a different foodstuff, with a much lower glycemic load than the produce of today’s selectively-bred monoculture.

    2. Psychoanalystus

      Really? Wow! Let me guess, you are either:

      1. a complete moron, OR
      2. a Monsanto employee.

      What is it?

    3. travizm

      Corn is def. a problem grain for digestion. This is well documented in Indian tribes also.

      Fructose, in general, is metabolised poorly leading to an increase in “bad fats”.

      From skimming the research paper, Im not sure they controlled for the amount of fructose in control and experimental groups….because ill bet you a million Z$ that GM corn is going to have a higher mass fraction of fructose and a higher mass fraction of energy density in total.

      So yeah Corn industry in USA has gotten too big to fail now and its killing people….there is so much corn that they are getting really creative in where they put it…….start reading your ingredients lists!! Scary shit.

      1. Stephanie

        Jardinero didn’t just say that corn (or more properly, maize) is a problem for digestion. He/She is saying that it causes diabetes, heart disease and obesity.

        1. travizm

          It does….they think the problem is Fructose.

          Google “fructose heart disease diabetes”

          Plenty of peak body peer reviewed evidence.

          The real dirty work as I see it is how the corn subsidies have been gained and maintained…..

          1. Brian

            I think you would be hard-pressed to consume too much fructose from an actual corn ear. It has to be heavily processed to make corn syrup.

          2. travizm

            whoa…i effed up here.

            Brian is 100% right in that fructose is enzymatically increased to make Corn Syrup sweeter and more soluble.

            Still that study would need to control for calories…

            But im completely dead wrong on this matter.

            Oops….should stick to commenting on things I know well…….nothing.


          3. Stephanie

            No worries. At least you came back to say that the information was wrong. Jardinero won’t be doing the same thing, I expect.

          4. Rob Lewis

            Beware the current scam of “agave nectar” as being a healthy sugar substitute. First, it is not a “natural” product: it is manufactured in much the same way as high fructose corn syrup. And yes, it has a low glycemic index, but that’s because most of its sugar is fructose, which doesn’t contribute to glycemic index but is the worst kind of sugar for your metabolism. Watch “Sugar: the bitter truth” on YouTube to have your eyes opened.

    4. Jordan M

      Corn has been domesticated for thousands of years and if incorporated in the correct portions it can provide a healthy part of the human diet. The real problem is GM corn, shown to have negative effects on lab animals internal organs, coupled with our society’s desire to use high-fructose corn syrup in every food product. To declare that “corn itself is the problem” simply isn’t accurate; go to the native cultures of Mexico and Central America, where corn is native, and tell them that corn shouldn’t be part of their diet.

  4. Jardinero1

    One other thing, all pest resistant plants are pest resistant because they produce their own pesticides. My brother, who is a botanist, made this observation about organic foods in some controlled studies which he supervised. He observed that many organically grown vegetables which had developed resistance to pests had developed internal pesticides. The level of pesticide in the organic vegetables was higher than the level of pesticide in non-organic vegetables which had been oversprayed with pesticide during production.

      1. Jardinero1

        The conclusion was that one would ingest less pesticide from a pesticide oversprayed but properly rinsed non-organic tomato than from an organically grown tomato which had produced its own internal pesticide.

        1. Stephanie

          Okay. so you ARE equating all pesticides. Read the other comments under your original comment. Your blanket statement is absolutely ridiculous. Plants evolve mechanisms for protecting themselves. People evolve mechanisms for dealing with those ‘pesticides.’

          1. Jardinero1

            No, I said “one would ingest less pesticide from a pesticide oversprayed but properly rinsed non-organic tomato than from an organically grown tomato which had produced its own internal pesticide”. I make no judgement about the toxicity or equivalence of naturally occurring organic pesticides vs a man-made pesticides. Naturally occuring, organic pesticides could be more or less harmful to man than man-made pesticides, that would be a different study.

          2. stephanie

            then the study has no meaning. They aren’t the same compounds. It’s like comparing apples to elephants.

          3. Brian

            To be fair, the Bt gene put into many GM crops produces the same insecticide that organic farmers apply to their crops.

          4. Stephanie

            That isn’t really a fair thing to say. Bt isn’t in that many crops (certainly not vegetables, beyond potatoes and corn…though corn is a grain, and not a vegetable), and Jardinero didn’t specify which pesticides, anyways. All ‘pesticides’ are not equal, and just because a plant has evolved mechanisms to protect itself doesn’t mean you get to call it a pesticide and then equate it with neonicotonoids, or something.

            And also, yeah..thanks a lot Monsanto for using Bt, which has increased pest resistance to it (as if they didn’t know this would happen. This is what insects do….they evolve resistance quickly, and that is why they are so successful), thus reducing the tools for organic farmers.

    1. Psychoanalystus

      Really? And, if your brother (the “botanist”…LOL) tells you that plants make their own Agent Orange, you’d believe that too?

      Like I said, you’re either an imbecile or a Monsanto ass kisser.

    2. travizm

      Now this one is bit of a stretch…

      Yes of course plants have evolved to produce molecules which make the plant & its immediate environment less appealing.

      However….humans have co-evolved in this process and our molecular machinery has learned to make the most of these things.

      In fact this is one of the theories as to why organic is healthier….and def. why organic tastes better!

    3. Bill

      Onions have evolved to make nasty tasting sulpher compounds. That’s why you cry when you slice them. That has nothing to do with chemicals synthesized in surplus nerve gas factories which is how the pesticide industry got started.

      It’s fascinating to see how the pro corporate lapdogs seize on almost magical thinking and simplistic intellectual jargon to push the causes that their masters’ voice plants in their puny brains. I expect any day now that procorps will start referring to astrological star charts…

    4. LAS

      Thank you for the explanation. I’d been wondering why there are so few insects in the organic produce that is brought to market. Also, how true organic products could have been produced on the scale we’re seeing in the supermarkets. Both of these observations now make better sense if the food is genetically modified or engineered. The supermarket doesn’t tell you anything of course.

    5. Stephanie

      I just want to clearly draw attention to this obfuscation on the part of Jardinero. This is what this industry does. There is so little long term empirical evidence showing their crops to actually be effective doing what they say they’ll do. And, along the way, they use fear and obfuscation to rationalize their products. Also along the way, they are chipping away at a healthy food system by making it less diverse and less resilient.

    1. bmeisen

      What about obesity rates in countries that also eat a lot of GMO? Indians for example reportedly eat lots of GMO rice, and GMOs are also big in Brazil and China I understand.

      GMO’s and their producers must be handled carefully but the RT report and your commenters are piling on with regard to GMOs and obesity. They and their creators cause a lot of yet unspecified problems, I do not doubt, but American obesity is more likely to be a consequence of many factors, among which GMOs are less relevant.

  5. Conscience of a Conservative

    Personally, I’d go natural, but life is about choices and I know my choice implies higher food prices.

    We have an increasing world population, a decrease in wild fish and wild species. Then we have plant based vegetation which cannot be grown as economical as plants that take advatange of modern fertilizers and may themsevelves be GMO. Basically it’s about choices, either the price of food goes up and people starve or we use GMO or use pesticides. The world can’t subsist on grass fed beef and organic vegetables and still be fed cheaply with everyone eating.

    1. Bill

      Bullshit. More important than yield, from the farmer’s perspective, is income, and here organic is clearly superior. The 30-year comparison showed organic systems were almost three times as profitable as the conventional systems. The average net return for the organic systems was $558/acre/ year versus just $190/acre/year for the conventional systems. The much higher income reflects the premium organic farmers receive and consumers pay for.
      But even without a price premium, the Rodale study found organic systems are competitive with the conventional systems because of marginally lower input costs. Importantly, the Rodale study, which started in 1981, found organic farming is more sustainable than conventional systems. They found, for example, that:

      . Organic systems used 45 per cent less energy than conventional.

      . Production efficiency was 28 per cent higher in the organic systems, with the conventional no-till system being the least efficient in terms of energy usage.

      . Soil health in the organic systems has increased over time while the conventional systems remain essentially unchanged. One measure of soil health is the amount of carbon contained in the soil..

  6. Psychoanalystus

    The only way to rid the world of criminal scum like Monsanto is to boycott them into extinction. You may have to pay more for food now in order to eat organic, but it sure as heck it’s going to be cheaper than paying for a liver transplant or a triple bypass 20 years from now.

    So just boycott the sons of bitches. ONLY buy organic. Drive Monsanto into bankruptcy. It is as simple as that.

    1. MattC

      In fact this is the most important point in a corporatised global world where the least cost solution always wins without any care or consideration to the people. They play by markets so hit them the only way a market gets hit – demand side.

      1. Jordan M

        People have saved seed for generations themselves, some of these heirloom seed companies have been around for more than 100 years. Monsanto doesn’t sell corn seeds from genetic lines that hundreds of years old…
        There was once a time that every farmer used to save their own seeds…
        and there seed companies have existed for a long time, before Monsanto came to dominant the agricultural market.
        Do some fucking reading!

  7. Carl

    Californians who are registered to vote have a unique opportunity to do something about this. Get out and sign the petition to put a proposition on this falls ballot that would allow voters to chose to label genetically modified
    food sold at retail.

    Here’s more of the science and the negatives of this frankenfood:

    Download this paper to learn more about the Genetically Modified Food Facts & Hazards. This presents the key scientific evidence – 114 research studies and other authoritative papers –documenting the limitations and risks of GM crops and the many safer, more effective alternatives available today.

    Sign the petition. Put the issue on the ballot.

  8. emptyfull

    It’s exactly this sort of corporation-fuelled “science” that adds to suspicions about the validity of other types of science. Instead of wasting so much breath condemning religious conservatives on issues like evolution, they should focus the public’s attention on how science gets corrupted by the financial interests of those who fund them.

    Oh wait, doing that would decrease many scientists’ gravy trains. Go after the mostly powerless “rubes” in “flyover country” instead. Then pat yourself on the back for having “defended science.”

    Not an anti-science statement at all — just a note that the real threats to science (like capitalism) often come from fraud within rather than oppositional ideologies.

    1. Dale


      I nominate you for the chief spear thrower at airplanes passing over your chosen territory. Have you ever had the good fortune to be able to sniff at, let alone eat out of the KochMeisters garbage cans?

  9. Fiver

    It’s a matter of “when” not “if” as to a first order environmental debacle with Monsanto’s name on it. This company was Too-Big-To-Allow long ago.

    They’ve essentially cornered Everyman’s diet and I can’t see any restraint coming from US regulators until AFTER something very ugly happens – should the event be a monoculture-related one, the effects of an unintended design weakness are now potentially huge in any number of countries all over the Globe. Reducing hundreds of durable, time-tested varieties to a mere handful, to then grow over immense areas, in the face of rapid climate shifts, human transmission of myriad invasive species everywhere, the obvious threat of some “super-pest”, seen from a local, national or global food security policy angle, is so completely mad that you have to seriously consider whether this has long been more about strategic control of a huge percentage of the global food supply, than any purported “value-added” of the product itself.

    Monsanto undoubtedly has a role to play in “national emergency preparedness” as per this Executive Order Obama signed Friday – a real freaker:

    Monsanto, and all these megashits, Government and private, are very nearly fused. This is their Plan. All very legal in the time that law forgot.

      1. Fiver

        Well, there has to be SOME reason for occupying Afghanistan:

        I don’t expect the “rare earth” shortage to end in open conflict, as there are substantial, known deposits in a number of countries, and it is more a question of production/environmental costs than anything else.

        One does have to scrutinize the wisdom of a company, industry, or country committing the entire world economy’s future to an information/communications technology prior to assessing the ease and security of supply of critical resource inputs. Perhaps the US was quite happy to have China mine and process the stuff, even at a premium, if it both helped secure multinational industrial production facilities and workers in China of items involving the use of these “earths” – a cost of doing business that also off-shores the very serious negative environmental impacts. Or maybe everyone but the Chinese were asleep at the switch. Thanks for the link and comment.

  10. Cuppasoup

    Why no labeling of GM ingredients?

    The answer is obvious: Regulatory capture by the industrial food conglomerates. Give people a choice and their hold on the market would probably crash.

    Give us labeling!!! It’s long overdue!

    1. Union Carbide Murders

      Bayer kills bees: neo-nicotinoid pesticides proven toxic to bees. This was after years of confusion, and talk of the end of the world. The long chain hydrocarbon profiteers were entertainingly documented in a moody, somnolent documentary ‘The Corporation’. (We need another musical entitled “F&^k the Banks”. strictly off Broadway – to boost the nations mood in these days of financial tyranny.)

  11. nmtdoc

    Anyone interested in the current science of this debate regarding grains should go to

    With regard to GM crops there should be no debate. If money and politics were not so deeply intwined, these things would be banned.

  12. Wade Riddick

    This might be linked to the damage pesticides do to gut bacteria. These friendly bacteria digest dietary fiber and transform it for our benefit. In particular, bacteria process inulin in food into GLP-1, an anti-inflammatory/insulin sensitizer. Inulin, by the way, costs under $200 a year whereas expensive GLP-1 agonists used to treat the diabetes caused by stripping fiber out of our foods runs about $4K. (And why is it, exactly, that nobody in the press corps ever referred to pizza magnate Herman Caine as the Diabetes King of America? ‘Cause he bribes them by buying food ads that pay their salary.)

    When you damage this symbiotic bacterial population with antibiotics, leftover pesticide residues or sugar (which feeds competing Candida populations, leading to fungal overgrowth) you can get forms of insulin resistance like obesity and polycystic ovarian syndrome (PCOS). It can also cause or contribute to autoimmune diseases. While antibiotics are frequently the culprit, poor diet (like processed corn sugar) and toxins also contribute.

    PCOS, by the way, is what Sandra Fluke’s friend suffers from (you know, the one who was castrated because the Catholic Church wouldn’t pay for a life-saving hormone pill because they supposedly favor life). PCOS causes ovaries to pump out excess levels of androgens. Androgens – in women, anyway (it’s slightly different in men) – enhance women’s interest in having sex with men and other women. Isn’t it funny how the Iowa corn lobby votes Republican, denounces welfare, confiscates our tax dollars to grow the corn that makes us sick, denies us medicine like hormone pills and then wins elections by beating up on gay people?

    It’s like Rube Goldberg and Thomas Nast made one of those test tube babies that freak Rick Santorum out – except the baby is voting for Santorum.

    1. Dave

      You can get edible inulin from one of the easiest crops to grow, sunchokes, or jerusalem artichokes.

  13. Aquifer

    Thank you, Yves, for posting on this! If CDS’s are the WMDs (as Buffet would say) of the financial system, GMOs are the WMDs of the food system.

    As patented life forms, they are quite clearly mechanisms for consolidating control of our food supply by agribusiness and, quite aside from the health effects, should be banned for this monopoly power alone.

    The FDA claims it doesn’t need extensive testing because it has declared that these “foods” are “substantially equivalent” to non-GMOs, without doing any testing to see if, in fact, they are – they just took the industry’s word for it ..

    GMOs have been sold on the basis of claims of “increasing yields”, but, as someone mentioned above, that is baloney. Organic farming, crop rotation, and combination of crops produces higher yields, not to mention healthier soils, and by extension, more nutrient rich foods.

    Monsanto, are fighting fiercely to prevent labeling because they know what would happen – folks would choose to not eat the stuff.

    Folks complain it is more expensive, but if we would stop subsidizing agribusiness and start subsidizing organic, that could change overnight – another political decision. Organic is also considerably less fossil fuel intensive. It is rather bizarre, when you think about it, that we now have to label food “organic”; for eons all food was “organic”.

    High tech in e-stuff might be useful, but in food it is a disaster. Our bodies weren’t made for it and we are demonstrating that more and more. The tie-in with healthcare issues and costs couldn’t be more obvious, IMO ..

    1. Fiver

      OK. I’ll bite. Please do offer up a pearl

      Are you offended on behalf of Monsanto. Other corporate criminals? Or is it the whoring and profoundly stupid arrogance in so much of Science you rise to defend?

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