Do GMOs cause health problems in people?  The governments of America, Canada and Australia say genetically engineered foods have proven their safety over the 20 years they have been part of the food chain.  According to the USDA, “the risks of genetically engineered (GE) organisms are not fundamentally different from risks posed by non-GE organisms with similar traits.”

Eighty transgenic crops have received regulatory clearance in our country, though only about a dozen are currently marketed for human consumption.  Because these dozen include corn and soy beans, though, 70% of US grocery store foods include GMO ingredients.

American federal agencies agree with highly respected and persuasive scientific institutions here and in Great Britain who maintain there is no evidence GMOs harm people.  These groups characterize GMO opponents as touchy-feely, mushy-headed conspiracy theorists who don’t understand hard science.

On the other side, opponents of GMOs say there is plenty of real evidence that GMO foods are unsafe.  They maintain that most of the entities who claim GMOs harmless have significant vested interest in them, that the vast majority of safety trials have been run by the biotech industry itself, without government oversight, and there is no public access to data produced in private that contradicts safety claims.  They also say there are virtually no long-term trials that would prove safety with more certainty.

Peer review, the process by which science checks and double-checks itself, is the most independent, reliable source of information we have today.  This research can generally guide our understanding of the facts better than any other source.

Having said that, the vast preponderance of published, peer reviewed studies state that GMOs are safe.  These studies have led to the theory of “substantial equivalence,” which means that GMO crops are presumed to be generally the same as non-GMOs in their effects.  Substantial equivalence has been adopted by many governments, and in practice, the theory means that no long-term studies need to be done.

Beyond substantial equivalence, a new term has developed called “biological relevance.”  This is used in cases where studies do show differences between animals fed genetically modified and non-genetically modified foods.  In practical terms, the result of biological relevance is that though there may be statistically significant effects of GMO -fed animals (such as changes in kidney and heart function, impaired immune symptoms, cellular changes in the liver and pancreas), they are not important enough to matter to regulators.

Research that shows a relationship between GMOs and health are attacked for reasons other than “substantial equivalence” and “biological relevance,” and these studies indicate the high emotion and level of scientific antipathy on both sides.

Many studies say GMOs cause damage to the beings that eat them.  Among them:
1) A Norwegian study published in 2007 found a number of significant differences in the liver and intestines of fish fed GM and non-GM corn (maize) and stated that, “GM maize seemed to induce significant changes in white blood cell populations which are associated with an immune response.”

2) A 2011 European study of GM plants showed that the toxins engineered into plants (to kill insects) had an effect on human cells, “and that they can present combined side-effects with other residues of pesticides specific to GM plants.”
Both sides of the issue site the American Medical Association.   The association says that people have eaten GM foods for close to 20 years and that “no overt consequences on human health have been reported and/or substantiated.”  It also says, however, “a small potential for adverse events exists,” including the possibility for “horizontal gene transfer, allergenicity and toxicity.”

The AMA agrees with scientists on both sides when it says, “regulation of bioengineered foods should be science-based and involve systematic safety assessments.”

Pro-GMO scientific perspectives can be found at Biotechnology FAQ USDA, and the opposing view at