GMO foods are foods made from organisms whose DNA has been altered in a laboratory rather than through traditional breeding. The process involves identifying a gene that produces a desired trait in one organism, copying it, and inserting it into the DNA of a different organism, typically a crop plant. The result is a plant with characteristics it wouldn’t develop on its own, like built-in pest resistance or the ability to survive herbicide sprays.
How Genetic Engineering Works
Traditional plant breeding works by crossing two related plants and hoping the offspring inherit the right combination of traits. Genetic engineering skips that process entirely. Scientists identify the exact gene responsible for a useful trait, copy it from the source organism, and insert it directly into the DNA of the target plant. The modified plant is then grown and tested to confirm it expresses the new trait.
The two most common traits engineered into crops are insect resistance and herbicide tolerance. Insect-resistant crops contain a gene borrowed from a naturally occurring soil bacterium. The gene produces a protein that is toxic to specific insect pests: when an insect eats part of the plant, the protein binds to cells in its gut, forms pores, and kills it. The protein is harmless to humans because it only activates in the alkaline environment of an insect’s digestive system, which is chemically different from ours. Herbicide-tolerant crops, meanwhile, are engineered so that farmers can spray weed-killing chemicals on an entire field without damaging the crop itself.
Which Foods Are Genetically Modified
The USDA maintains an official list of bioengineered foods available on the market. It’s shorter than most people expect. The crops currently on the list are:
- Corn
- Soybeans
- Cotton (used for cottonseed oil)
- Canola
- Sugar beets
- Alfalfa (primarily animal feed)
- Papaya (ringspot virus-resistant varieties)
- Summer squash (virus-resistant varieties)
- Potatoes
- Apples (Arctic varieties, engineered not to brown)
- Pineapple (pink-flesh varieties)
- Eggplant (insect-resistant varieties grown outside the U.S.)
- Sugarcane (insect-resistant varieties)
- Salmon (AquAdvantage, the only approved GMO animal)
Corn, soybeans, cotton, canola, and sugar beets dominate the GMO landscape. Because these crops are processed into ingredients like corn syrup, soybean oil, and sugar, they show up in a huge number of packaged foods. If you eat processed food in the United States, you are almost certainly eating GMO-derived ingredients on a regular basis. Fresh produce, by contrast, is rarely genetically modified. The non-browning apple, pink pineapple, and virus-resistant papaya and squash are the exceptions.
How GMO Foods Are Regulated
Three federal agencies share oversight of GMO foods in the U.S. under a framework established in 1986. The FDA ensures that GMO foods meet the same safety standards as all other foods. The EPA regulates the pest-killing proteins built into insect-resistant crops, treating them as a type of pesticide. The USDA’s Animal and Plant Health Inspection Service evaluates whether GMO plants could become harmful to other plants or the broader agricultural system.
Since January 2022, a national labeling law requires food manufacturers and importers to disclose bioengineered ingredients. You’ll see the disclosure as text on the package, a symbol (a green circle with the sun and a field), or a QR code. The standard applies to foods sold at retail and is meant to give consumers a consistent way to identify GMO ingredients regardless of where or how a product is made.
Effects on Pesticide Use
One of the most cited arguments for GMO crops is that they reduce pesticide use. The data broadly supports this, though the picture varies by crop. Between 1996 and 2020, GMO adoption reduced global pesticide application by about 749 million kilograms of active ingredient, a 7.2% decrease compared to what would have been used on conventional crops. The environmental footprint shrank even more, dropping 17.3% by a measure that accounts for toxicity and persistence, not just volume.
Insect-resistant cotton has delivered the single largest reduction: roughly 339 million kilograms of insecticide avoided, with the associated environmental impact falling by about a third. Herbicide-tolerant canola cut herbicide use by around 20% in 2020 compared to conventional canola. Corn and cotton saw modest herbicide reductions as well. The one exception is sugar beets, where GMO varieties slightly increased herbicide use by about 4.4% in 2020. Soybeans, the most widely planted GMO crop, showed essentially no change in herbicide volume in 2020.
Safety of GMO Foods
The scientific consensus on GMO food safety is clear. The National Academies of Sciences, Engineering, and Medicine concluded that genetically engineered organisms pose the same risks as organisms modified through conventional breeding and present no unique health hazards. This position has been echoed by the World Health Organization, the American Medical Association, and scientific bodies across Europe and Asia. Decades of research and billions of meals have not produced credible evidence that approved GMO foods cause harm to humans.
That doesn’t mean every possible genetic modification is inherently safe. Each new GMO product goes through its own review process. What the evidence shows is that the process of genetic engineering itself does not make a food dangerous. A GMO corn chip is nutritionally and toxicologically comparable to a conventional corn chip.
Gene Editing and the Next Generation
A newer technology is blurring the line between GMO and non-GMO. Traditional genetic engineering inserts foreign DNA from another species into a plant’s genome. Gene editing tools like CRISPR work differently: they make precise cuts to a plant’s existing DNA, altering genes the plant already has rather than adding new ones from outside. The result can be indistinguishable from a mutation that might occur naturally or through conventional breeding.
This distinction matters for regulation. In the U.S., gene-edited crops that don’t contain foreign DNA are generally treated as non-GMO and can reach the market without the lengthy approval process required for transgenic crops. Argentina and Brazil follow a similar approach. The European Union, however, treats all gene-edited crops as GMOs regardless of whether foreign DNA is present, regulating based on how the plant was made rather than what’s in it. This split means a gene-edited crop might be labeled as non-GMO in the U.S. but classified as a GMO in Europe, even though the end product is identical.