Study: Genetically Modified Corn Increases Body Weight in Rats

GM Food 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.

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

Many past studies have also shown health and environmental problems from GM foods. No wonder 92% of Americans – and 55 members of Congress – want mandatory labeling of GM foods. But the FDA hasn’t yet gotten the message.

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  • I am struck by how the argument about GM foods is won or lost. Should the United States government protect its people from food that can be shown to harm it in the short and long run? This is a question that is answered by staffing the government with officials paid by the GM food industry. There is no sense in which the U.S. has shown that it has tested and then ruled based on its tests these GM foods for safety.

    I am confused by the fact that if we were talking about pharmaceuticals, the industry would promote the idea that complex testing procedures were necessary before any drug was put on the market. I have the idea that with pharmaceuticals, this concern about testing is a way of protecting the drug companies from competition. So, herbs and vitamins cannot claim or be promoted as having any effect on one’s health because there has been no testing of their effectiveness and safety. This is also a way of making sure that start up companies that might find some drug that is obviously of some benefit cannot market their drug to the harm of bigger drug companies.

    So, I can’t tell if I would advocate testing of foods for safety, or not. In either case there is reason to think the big companies will use the law to make money at the public’s expense and to its detriment.

    What’s more, I thought Obama promised to keep lobbyists out of government as best he could, once in office. wasn’t that one of his campaign promises? That Monsanto lobbyists and lawyers are such a big part of his administration doesn’t surprise me, though.

    I am also struck by yje fact that the issue of there being chemicals in our food that might be making us fat instead of out eating and exercise habits is completely ignored by surgeons who are making money off of fat people, promising that if they have stomach reduction surgery, they will have better and thinner lives again. According to these reports, there’s a good possibility that eating habits have had little if any impact on obesity in America. Isn’t the surgical solution to obesity just a fraud on people? Shouldn’t doctors investigate whether there is any chance that surgery could be of any help?