Are Genetically Modified Foods Safe?

GMO foods are unnatural and will kill us all, right? It turns out, these crossbreeds might not be as unnatural as you think. Ask Science explains.

Lee Falin, PhD
5-minute read
Episode #19

Are Genetically Modified Foods Safe?

by Lee Falin, PhD

Nothing says "controversy" like genetically modified food. In my experience it seems to be the one issue that unites people across the political spectrum. But what is genetically modified food, and why all the hoopla?



Genetic Legos

Speaking of being united, nothing unites my children like Lego blocks. When a new Lego set arrives, they'll sit in the playroom together for hours, happily building, playing, and sharing. It's like a little Lego utopia in there. Frequently they'll be working along and one of them will hold up a piece and ask "Does anyone have a blue piece shaped like this?" The problem of course is that the child has a specific vision in mind for what he wants his structure to be, but lacks the exact piece to create it. Fortunately, one of his siblings usually knows where to find the piece he’s looking for.

Genetically engineered food works along a similar vein. Suppose that you're a farmer and you grow two kinds of crops, soybeans and peanuts. One year, blight comes through and wipes out most of your soybeans, but doesn't affect the peanuts at all. Wouldn't it be nice if there were some way to take whatever it is inside the peanut that protected it from the blight, and share it with the soybean plants? With genetic engineering, there is a way to do just that.

Using special techniques, scientists can identify the genes in peanuts that are responsible for protecting them from the blight, make a few copies, and then stick them into the genome of the soybean plants. Just like a group of kids sharing Legos.

Farmer in the Dell

Farmers have been practicing genetic manipulation of crops for centuries, just using methods that take longer and are less exact. Anytime a farmer crossbreeds two plants or animals that have shared characteristics they want to merge, they are engaging in a form of genetic engineering. Crossbreeding is a way to merge the desired genetic traits of two or more distinct lines into a single organism that will share those traits. For example, Jersey Cows are known for high milk production and are sometimes cross-bred with cows in other locations to produce breeds which are both adapted for local environments and have high milk production.

Beware the Frakenfood

So if this is just a more precise version of what every farmer on the planet has been doing for thousands of years, why is everyone so upset about scientists using more exact methods to carry out the same process? Depending on whom you ask, you'll get different answers to this question, but here are some of the more common objections to the so-called Frankenfood:

Objection #1: Unnatural Hybrids                           

While farmers can manually pollinate one corn plant with the pollen of another corn plant and get hybrid corn seeds, they can't use the pollen from tomato plants to pollinate corn and hope to get some corn/tomato hybrid. (I discussed some of the reasons behind this in my episode on interspecies relationships).

Scientists, on the other hand, can mix the genes of any organism, even genes from different kingdoms. This means that they could potentially take genes from bacteria and animals and mix them with the genes of plants. How outrageous! How unnatural! How just like horizontal gene transfer! Wait, what?

Yes, it turns out that this type of willy-nilly gene sharing already happens in nature all the time, in a process called horizontal gene transfer. While most genetic information is passed "vertically" from parent to offspring, sometimes genetic material can be passed between organisms that aren't immediately related at all. While this process happens mostly in closely related single celled organisms, such as bacteria, there is increasing evidence that bacteria and some viruses can facilitate the transfer of genetic information between organisms that are less closely related (like you, me, corn, monkeys, etc.) as well. And this brings us to objection number two...

Objection #2: Gene Leakage

I know it sounds gross, but gene leakage is really just a sensationalized term for the idea that horizontal gene transfer might happen in a way that would have unintended consequences on the environment. For example if there was a corn plant engineered to be resistant to weed killer, and those weed killer-resistant genes were horizontally transferred to weeds, you'd end up with so-called super-weeds which are resistant to weed-killer as well. While this might sound far-fetched, it’s already happening.

Objection #3: Intellectual Property Issues

Making the gene leakage issue even leakier is the idea that intellectual property laws typically protect genetically modified plants. This means that farmers are legally prohibited from saving seeds from these plants from year to year, and instead must purchase them from the creators or their authorized distributors. This turns out to be nothing really new, as the process plant patenting has been going on since the 1930s, while scientists only discovered how to transfer genes between organisms in the late 1940s.

Objection #4: Health Issues

The final and most common complaint you hear is the impact of genetically modified food on human health. Some argue that taking genes from one organism and introducing them into a new environment may produce unintended consequences. There is a famous case where a gene from the Brazil nut was introduced into soybeans in order to increase the protein yield. The unintended consequence was that people with Brazil nut allergies were also allergic to this new breed of soybean.

While this might sound like a great reason to ban genetically modified foods, it's important to realize that this kind of thing can also happen in traditional plant breeding as well. The most famous examples of this include potatoes, where new varieties have sometimes contained levels of solanine too high to be consumed, and celery where certain breeds contained such a high level of a certain toxin that people harvesting the plants started to develop skin rashes.

The interesting thing about genetically modified vs. traditionally crossbred plants and animals is that GMO foods are required by law to undergo stringent testing for toxicity and allergenic effects (among other things) before being released to market. No such testing is required for traditionally bred organisms. (Though some countries have passed specific laws regarding the importation of certain plant and animal breeds).


So is genetically modified food safe? This is a little like asking a child whether or not there is any risk of building something dangerous with a pile of Lego blocks. There are endless possible combinations of genes, some combinations are safe, and some are not.

A better question to ask is: Are new genetically modified varieties of crops more dangerous than new varieties bred through traditional methods? The answer here is that neither appears to be more dangerous than the other, but current legislation makes it much less likely that you would be harmed by a new GMO variety than you would a new variety bred by traditional means.

Soybeans and Farmer images from Shutterstock

Please note that archive episodes of this podcast may include references to Ask Science. Rights of Albert Einstein are used with permission of The Hebrew University of Jerusalem. Represented exclusively by Greenlight.

About the Author

Lee Falin, PhD

Dr. Lee Falin earned a B.S. in Computer Science from the University of Illinois, then went on to obtain a Ph.D. in Genetics, Bioinformatics, and Computational Biology from Virginia Tech.