Do I need to worry about GMOs? What experts say about genetically engineered food.

Photo illustration of a yellow double helix nestled into corn stalk leaves, straddled by two corn ears.
Photo illustration: Axel Rangel Garcia for Yahoo News; Photo: Getty Images

Many people avoid “GMOs” at the grocery store, instead selecting foods labeled non-GMO or the organic versions of items from apples to oats, as they are worried about ingesting genetically modified organisms (GMOs). Still, you may be wondering exactly why these products are so controversial — and whether you should adjust your own eating habits in order to avoid them too.

Right now, the jury is out on whether GMO foods should absolutely be avoided — but here’s why some people want to skip putting them on their plates.

What are GMO foods?

Genetically modified organisms refers to any plant, animal or microorganism that has been genetically altered, due to modern biotechnology like genetic engineering. Often, GMOs are labeled “GE,” referring to “genetically engineered.”

Crops can be genetically modified to be larger, more resistant to bacteria and disease, more nutritionally dense and even to taste a certain way. There are many advantages to having the ability to genetically alter crops when you need to feed billions of people around the globe.

“Certain bananas have been genetically modified with genes from green peppers,” says Amber Core, a registered dietitian at the Ohio State University Wexner Medical Center. “Green peppers have this ability to fight off certain bacteria that attack bananas and causes them to rot from the inside. We add in this gene that already exists naturally in these peppers to the banana, and then they are able to fight off that bacteria.”

Danielle Crumble Smith, a Georgia-based registered dietician, says that, originally, the idea behind these GMOs was “really good.”

“There was talk of ending world hunger, and making food less expensive to people who need it,” she explains. However, she says, these goals “have not yet happened.” And there are some potential risks associated with GMOs that may give people pause when it comes to deciding whether or not to eat them.

Why do some people avoid GMOs?

Some people may assume that changing the genetic material of a crop is what makes GMOs inherently harmful, likely because we associate altering of DNA with things like cancer and other diseases. However, Smith says that “the foods in and of themselves that are genetically modified are not necessarily harmful.”

Instead, “where there is risk has to do with how these foods are grown.” Specifically, Smith says, GMO foods are “engineered in a way that resists the pesticides that are used,” which means you may be exposed to more pesticides than with conventional crops. The specific pesticide that rings alarm bells is glyphosate, which is used in the weed killer Roundup, as many crops are genetically modified specifically to survive Roundup.

Glyphosate, which was commercialized in 1974 by the company Monsanto for use in Roundup, is highly controversial — and a big reason why many people choose to buy and consume foods with the non-GMO label.

Glyphosate is great for killing weeds that can harm crops — but it’s also capable of killing those same crops as well. That’s why, in 1996, Monsanto created a GMO that Roundup could be used on without destroying the crop itself — the “Roundup ready” soybean. Other Roundup-ready crops, such as cotton and corn, soon followed.

The company Bayer, which acquired Monsanto in 2018 and has since faced extensive litigation over whether Roundup causes cancer, claims glyphosate is safe, and the Environmental Protection Agency (EPA) says it is "not likely to be carcinogenic to humans."

Yet others disagree. The World Health Organization’s International Agency for Research on Cancer classified it as “probably carcinogenic to humans.” Studies have linked glyphosate to gut issues and hormone disruption, as well as non-Hodgkin lymphoma.

Where things get tricky

There’s a flip side to the GMO debate as well. Core says that crops that are not fortified through genetic modification often have to be sprayed with more pesticides, in order to ensure a more fruitful yield — otherwise, bugs and diseases can infect the weaker crops, killing them or making them unfit for consumption.

“Standard corn, versus the ‘Roundup Ready’ corn, is going to be treated with more of those [non-Roundup] pesticides,” she says. “[But with ‘Roundup Ready’ crops,] we’re not losing it due to disease, due to weed overgrowth or insects.”

Therefore, Core says, farmers may be able to create better, stronger and simply more crops using Roundup — while also avoiding further harmful implications from excessive pesticide usage.

“With any genetically modified food, it goes through a lot of different testing for safety, by the FDA, USDA and also the EPA,” Core says. “Not only are we concerned about whether this food is healthy for the population, but also is it safe for the environment.”

Yet the debate is still out as to whether GMO foods use more or less chemicals than their conventional counterparts. It’s complicated by the fact that, over time, the things that chemicals like glyphosate are attempting to kill can become resistant to the chemicals, meaning more of the chemicals need to be used to do the same job.

Are there any other reasons to avoid GMO foods?

Another concern about GMOs is that they may trigger an allergic reaction. For example, if a soybean is crossed with a certain nut, it’s possible that people with allergies to the nut may react to the genetically engineered soybean. While this may be true in theory, the Food and Drug Administration (FDA) says it is not a cause for concern. “Scientists developing GMOs run tests to make sure allergens aren’t transferred from one food to another,” says the FDA. “Research shows that GMO foods are no more likely to cause allergies than non-GMOs.”

What to know if you want to avoid GMO foods

Non-GMO foods are labeled as such. Not all non-GMO foods are organic, but all organic foods are non-GMO.

The best way to avoid pesticides, if that’s a health concern, is to go with organic food, as unlike organic foods, conventional, non-GMO foods are still likely exposed to pesticides. According to the U.S. Department of Agriculture, “Produce can be called organic if it’s certified to have grown on soil that had no prohibited substances applied for three years prior to harvest. Prohibited substances include most synthetic fertilizers and pesticides.”

Dietitian Marissa Meshulam says that when she is working with clients, she seeks to find balance, as organic foods are more expensive than nonorganic.

“If I’m working with a client who can afford it, I suggest organic food to limit the amount of exposure to pesticides,” she explains. “But if I’m working with someone who can barely afford to put food on the table, then canned conventional corn is better than no vegetables at all.”