Does Your Body Know You’re Eating Genetically-Modified Foods?

Yes, according to a new study that could have enormous impact on studies of cross-species communication, predator-prey relationships, and co-evolution.

First, let’s take a trip down memory lane for a brief refresher in high school biology.  Since 1958, molecular biologists have relied upon the Central Dogma to outline the rules of transfer of biological sequential information.  As you may remember from high school biology, DNA makes RNA makes protein.   In special cases, RNA makes DNA, RNA makes RNA, and DNA makes protein.  But protein doesn’t make protein, protein doesn’t make RNA, and protein doesn’t make DNA, or so says the Central Dogma.

Parsing complex studies and understanding the pathways of human DNA is an incredibly complex task.  Even if you are able to do so, it’s extremely difficult to write about such science at a level that laypeople (like myself) can understand.  Today in The Atlantic, Ari Levaux manages to do exactly that in his story, “The Very Real Danger of Genetically Modified Food.”  As a lover of analogies, I admire the way Levaux compares our current understanding of genetics to ordering pizza:

The Central Dogma resembles the process of ordering a pizza. The DNA knows what kind of pizza it wants, and orders it. The RNA is the order slip, which communicates the specifics of the pizza to the cook. The finished and delivered pizza is analogous to the protein that DNA codes for.

We’ve known for years that the Central Dogma, though basically correct, is overly simplistic. For example: Pieces of microRNA that don’t code for anything, pizza or otherwise, can travel among cells and influence their activities in many other ways. So while the DNA is ordering pizza, it’s also bombarding the pizzeria with unrelated RNA messages that can cancel a cheese delivery, pay the dishwasher nine million dollars, or email the secret sauce recipe to WikiLeaks.

One of the primary arguments in favor of the safety of genetically-modified food — the argument that “gene transfer” moves in one direction — has relied on the Central Dogma.  In simple terms, the FDA has trusted the basic idea that when you eat a piece of fruit, that fruit’s genetic material is not able to effect your genetic material.

But the new findings turn this argument on its head.  Lead by  Chen-Yu Zhang of Nanjing University, the Chinese researchers identified microRNA belonging to genetically-engineered plants (such as rice and cabbage) in human blood and tissue.  MicroRNA are fragments of RNA (the messenger between DNA and proteins) that typically silence or repress certain proteins by binding to and destroying the RNA that would have created that protein.  Indeed, the plant microRNA was found to inhibit a protein in human blood, “suggesting that microRNAs can influence gene expression across kingdoms,” writes Cristina Luiggi in her article, “Plant RNAs Found In Mammals,” published by The Scientist: Magazine of the Life Sciences.

Take a moment to note that ‘kingdom’ is the broadest of the seven major divisions of taxonomy.  We’re not talking about species or genus or family or order or class or phylum; we’re talking about genetic transfer across kingdoms — from vegetable to animal.  This is big news in the science world.

If the results of this study are verified, gene transfer is more complicated than humans ever imagined.  When you eat a piece of fruit, the genetic matter of that fruit (microRNA) is, in fact, communicating with — and influencing — your body’s genetic make-up (via protein inhibition).

Are genetically-modified foods unsafe?  The truth is, we don’t know.  We won’t know for several generations, since animal studies suggest that the full effects of consuming genetically-modified foods are not realized until the third generation of consumers.

But while we wait for science to catch up, age-old wisdom tells us, “You are what you eat.”  Today, Americans eat the same food that has been designed to make our cows gain as much weight as quickly as possibly: genetically-modified corn and soy.  And it has: cows that eat GMO corn and soy feed gain more weight faster than cows ever have in agricultural history.  We humans eat this same GMO corn and soy, and some of us even eat the cows raised on a diet of GMO corn and soy.  Doesn’t it stand to reason that this would make us fat, too?  And it has: American obesity has reached an all-time high.

In the meantime, the European Union, Japan, Malaysia, Australia, and other countries require genetically-modified foods to be labeled.  Labeling works on multiple levels, because it also means that special care must be taken to ensure that GMO foods do not contaminate non-GMOs.  With no real need to separate the two, the United States’ regulations on GMO-contamination are inevitably less strict.  In fact, because of this, in 2007, Europe rejected shipments of U.S. rice after discovering that the U.S. rice contained strains of engineered genes that had never been approved for human consumption — neither by the E.U. nor by the U.S.

UPDATE 1/18: Both Slate and the blog at Scientific American have published rebuttals to Levaux’s piece. 

My personal view is that, as American consumers, we should be informed about the contents of our food — that is, whether we are spending our money on genetically-modified food or not — so that we can make the decision for ourselves.

What about you?  Take the poll below to share your thoughts:

Photo Credit: I love the Tim Burton-esque photo accompanying Levaux’s Atlantic article (Dirk Ercken for Shutterstock).



    • Thank you for sharing both articles! I have made them available in my original post as well. I agree that there is evidence on both sides of this debate. However, at this early stage in GMO history, I believe GMO food should be labeled so that consumers are able to make the decision for themselves.

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