What Are GMOs and Are They Bad for Me?

The question of what a genetically modified organism (GMO) is and whether it’s bad for your health is an especially persistent one.
July 20, 2018, 7:12pm
carrots and kale on a pink background
Vice Media

Every day, we’re bombarded with food labels claiming that certain products are healthier than others. Walk the aisles of a grocery store (or even read a restaurant menu) and you’ll find yourself interpreting a dizzying array of health buzzwords like “low-fat,” “all-natural,” and, of course, “non-GMO.”

While there are problems with many of these labels, the question of what a genetically modified organism, or GMO, is and whether it’s bad for your health has proven to be an especially persistent one. “Humans like to put things in boxes; there’s the ‘natural’ box and the ‘unnatural’ box,” says Anastasia Bodnar, a plant geneticist and the policy director of the nonprofit plant-science organization Biology Fortified. “We know things like Diet Coke aren’t natural, but [GMOs] are different. They look natural but have been altered in ways people don’t understand.” And that, it seems, scares us.


Starting in 2020, large companies that make bioengineered foods will have to label those products in some form, which may further solidify the popular belief that GMOs are unappealing Frankenfoods—and make “non-GMO” foods sound healthier and more natural by comparison. But that’s very misleading. Here’s what you need to know.

First things first: What exactly is a GMO? Am I eating them already?

Genetically modified organisms are defined by the World Health Organization as “organisms (i.e. plants, animals, or microorganisms) in which the genetic material (DNA) has been altered in a way that does not occur naturally by mating and/or natural recombination.” Selectively bred animals or plants are considered GMOs—and few people have problems with techniques like plant grafting—but what we’re talking about here is using technology to alter genes. For clarity, we’ll call it GE, for genetically engineered. This term specifically refers to using tools to cut and paste recombinant DNA in the laboratory. (Even the FDA prefers “genetically engineered” in this case.)

Produce like the Red Delicious apple or the Cavendish banana that have been around for decades are not GE, since those foods were created by selective crossbreeding. The first GE crop—the Flavr Savr tomato—wasn’t introduced to the general market until 1994.

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The cutting and pasting of DNA is “the process of being able to cut out a specific gene and recombine it back into the genome of a cell that you want to change,” says Peggy Lemaux, crop biotechnologist at the University of California, Berkeley. While that might sound meddlesome, the results are no different from a plant that was genetically altered via selective breeding, and the process is much more precise.. “We already accept so many plants and animals in our food that have been bred to be totally different than how they were in nature,” Bodnar says. “Biotechnology is just another tool we can use.”

GE foods have become a huge part of our scientific lexicon over the past two decades, but you won’t actually find very many of them for purchase in the produce aisle. They’re mostly used in refined forms like soybean oil and cornstarch in processed foods. Lemaux says only a few varieties of genetically engineered whole produce are on the market, including sweet corn, squash, papaya, and most recently, the non-browning Arctic apple, which made headlines because it was so novel. (The Flavr Savr tomato is no longer sold.)


The two most common GE crops on the market right now are those with BT insect protection, or Bacillus thuringiensis, a “naturally occurring soil bacterium” that protects crops from pests when they have the trait added to their genomes, and “Roundup-ready” crops, which have been designed to allow farmers to spray the weed-killing herbicide glyphosate (aka Roundup) without harming the crops. Today, 89 percent of corn crops grown in America contain genes tolerant to herbicide.

I heard they’re bad for me. Are GE foods and GMOs unhealthy?

In short, there’s no reason to believe that genetically engineered foods are bad for your health. “People may fear that the genetic changes could directly interact with their own DNA and cause mutations in themselves or their future children,” says Ruth MacDonald, a food and nutrition scientist at Iowa State University. These fears, MacDonald says, are directly related to genetic illiteracy. She says genetic mutations in current or future generations as a result of eating genetically engineered foods is “of course not possible.”

“DNA that is consumed in food (note that all natural foods from plants or animals contain DNA—so we eat DNA all the time) is degraded and does not get ‘absorbed’ into the body intact,” MacDonald says. “It therefore is not logical to think that food-derived DNA could interact with the human genome.”

The American Cancer Society says, “There is no proof at this time that the genetically modified foods that are now on the market are harmful to human health or that they would either increase or decrease cancer risk because of the added genes.” Still the ACS points out that lack of proof of harm is not the same thing as proof of safety, so experts need to continue to assess and study these foods.


Gerald Berkowitz, professor at the Agricultural Biotechnology Lab at the University of Connecticut, says “the evidence is fairly clear that there is no documented, refereed science supporting a human health risk.” That’s not to say we shouldn’t be taking a critical look at their role in our food system, he adds: “When I look at GMOs in a broad context, there are many questions that the public should be asking. GMOs are very much reflective of big agriculture in the US [and] contribute to the industrialization of agriculture.”

Anti-GMO websites list a plethora of so-called toxicity and health concerns related to GE product consumption, like autoimmune disorders, infertility, and even autism, that they say are strongly associated with the use of glyphosate, an herbicide used on GE crops. The scientists we spoke to, however, said that studies have not (yet) found any proof of these claims, and a 2012 updated report distributed by the American Medical Association’s Council on Science and Public Health reconfirmed that “there is no evidence that unique hazards exist either in the use of rDNA techniques or in the movement of genes between unrelated organisms,” but similarly to the American Cancer Society, they strongly encourage the FDA to “remain alert to new data on the health consequences of bioengineered foods and update its regulatory policies accordingly.”

To take one claim: Yes, autism rates went up (there was a 15 percent jump between 2012 and 2014) at the same time that Roundup was increasingly used on crops, but correlation does not equal causation. A 2007 study published in the journal Environmental Health Perspectives, which examined the relationship between autism spectrum disorders and maternal proximity to farms that use pesticides (including glyphosate), failed to find a connection but said that the issue “should be further studied.”


Furthermore, the 2016 report Genetically Engineered Crops: Experiences and Prospects released by the National Academies of Science, Engineering, and Medicine concluded that “the overall similarity in prevalence of autism spectrum disorder in the United Kingdom, where GE foods are rarely eaten, and in the United States, where GE foods are commonly eaten, suggests that the major rise in autism spectrum disorder is not associated with the consumption of GE foods.”

Tonic reached out to the Non-GMO Project, a non-profit organization that produces the “Non-GMO Project Verified” label commonly seen in grocery stores, about their stance on the toxicity of GMOs, but they declined to comment.

There are a few reasons why certain GE foods aren’t great for you, but it has nothing to do with their having been genetically altered. One reason is that GE crops are commonly used to make ingredients like corn syrup used in processed junk food, which, newsflash, isn’t healthy.

Lemaux points out that a genetically engineered artichoke, for instance, is much less likely to be sold in major grocery stores than GE technology used for ingredients in processed junk food with name recognition. These foods “are being created by large companies that have to make money,” Lemaux says. “The regulatory process for GMO crops can cost anywhere between $10 and $20 million. My team has created four genetically engineered cereal crops and none of them went anywhere because we can’t afford it.”

Ok, so you’re saying GE foods and GMOs won’t give me cancer, either?

There’s no evidence that GMOs cause cancer. One reason you’ve heard that, though, is that, as mentioned above, there are a lot of GE crops designed to be used with the herbicide glyphosate, the active ingredient in Roundup, which was labeled a “probable carcinogen” by the International Association for Cancer Research, a World Health Organization committee, in 2015.

The announcement that a product used on common crops could cause cancer created subsequent outrage and division in the scientific community and the public. In October 2017, Reuters claimed that the IARC appeared to have edited or deleted data that was at odds with its conclusion of glyphosate being a “probable carcinogen,” while other critics claim that the IARC was looking at hazards (conditions that have the potential for harm), rather than risk assessment (the likelihood of those hazards actually causing harm). The WHO committee later released a report in January 2018 denying that it changed the data and defending its original findings.


The claims of glyphosate toxicity have been thrust back into the spotlight recently with the ongoing court battle between DeWayne Johnson, a California man who is dying of non-Hodgkin's lymphoma, and Roundup maker Monsanto over claims that the agrochemical giant has “specifically gone out of its way to bully…and to fight independent researchers” over alleged connections between glyphosate-based products and cancer.

Johnson worked as a groundskeeper for a California school district and regularly sprayed Roundup on plants and flowers as part of his job—and he was sometimes sprayed with the chemical himself on windy days—before he was diagnosed with his illness. Monsanto’s lawyers claim that non-Hodgkin's lymphoma “takes years to develop,” so Johnson's health problems likely began well before he started working at the school.

The outcome of this contentious court case could be an indicator of how similar lawsuits related to the herbicide might go, the Associated Press reports.

The tentative scientific consensus is that glyphosate has been a largely successful replacement for other, more harmful pesticides and herbicides like cyanazine, which was banned in the United States for toxicity levels in drinking water.

MacDonald says that the average person’s exposure to glyphosate doesn’t only come from GE crops and is likely pretty small. “The field corn grown with glyphosate resistance goes into things like starches, oil, and fiber,” MacDonald says. “You might eat those indirectly but they’re highly refined. Are there traces of glyphosate? Yes, but there will be traces in many foods because glyphosate is widely used in agriculture, not just [GE foods].” It’s used on more than 200 types of crops in California alone.


A 2014 review of studies from the University of California, Davis, and published in the Journal of Animal Science, found that the most direct consumers of GE crops—the livestock that eat genetically engineered feed—have suffered no “unexpected perturbations or disturbing trends in animal performance or health indicators.”

As for direct carcinogenic effects on humans, scientists admit that there hasn’t been enough rigorous research in people examining the correlation between GE crops and cancer, as the National Academies of Science, Engineering, and Medicine (NASEM) concluded in its 2016 report . However, data from the National Cancer Institute shows that numbers of deaths from the most common cancers have continued to either decrease or stabilize, even with the introduction of GE crops into the food system.

“The figures show that some cancers have increased and others decreased, but there is no obvious change in the patterns since GE crops were introduced into the United States food system,” the NASEM report’s authors conclude.

Are there benefits to GE and GMO foods?

There are. “There are thousands of interesting GE traits that could make a huge impact on disease resistance, nutrition, feed efficiency, and more,” Bodnar says. “But the trait has to get through regulation, the food manufacturer, and the consumer before it will go to market. We have so few of these tools available right now that they’ve become overused, and pests have developed a resistance. ”

As mentioned above, there are very few whole GE foods on the market right now—the only ones you will find in your supermarket include three varieties of squash, sweet corn, papaya, and the Arctic apple. Scientists have been scrambling to cut through red tape to get their new GE technologies approved and improve the genetic diversity of bioengineered crops.


One example of the complications related to emerging GE technologies is the creation of the non-allergenic peanut. Bodnar says scientists created these allergy-resistant peanuts a decade ago, but you can’t just put that product out on store shelves. You’d have to grow it in such a way that guaranteed no cross-contamination with regular peanuts, all the way from field to shelf. It’s not impossible, but it is expensive.

The scientists we spoke with are cautiously optimistic about the future of GMOs, from the vitamin A-fortified “golden rice” that is currently being tested in the Philippines, to new advancements in genetically engineered livestock like hornless cattle (which make the animals less dangerous to humans), and, as you’ve probably read about, salmon that have been genetically engineered to grow twice as fast by being injected with a growth hormone.

“These salmon would be the first GE animal in the food supply,” Bodnar says. “They’ve been in the regulatory process since 1995. You could do the same thing in different ways: You could genetically engineer the salmon or selectively breed them. It’s the same end result, but people hear ‘genetically engineered seafood’ and they want no part of it.”

Many scientists agree that GE technologies have a significant role to play in the future of agriculture and global nutrition (that is, if they can get over the hurdles of marketability and regulation), so why are “non-GMO” labels becoming more common on grocery store shelves and restaurant menus?

“It’s a total market strategy,” MacDonald says. “When you have people who think that [GMOs are] something to avoid and you can market your product to say it doesn’t have them, then of course you’d use that to your advantage.”

Additional reporting by Nicole Wetsman.

Editor’s Note, 3/1/19: After publication of this story, Tonic staff discovered that Ruth MacDonald writes content for GMO Answers, a website funded by agrochemical companies that make herbicides and crops that are genetically modified to resist those herbicides. MacDonald did not disclose this information to our reporter. When we sought her comment on this relationship, she told us she had not received compensation for her work on GMO Answers (the site also says that independent experts are not paid). We subsequently added the perspective of an additional source, Gerald Berkowitz, whose research funding comes from federal agencies, not the agricultural industry, and reviewed all the other sources quoted in this story; none appear to have conflicts of interest.

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