GMOs in food are plants or animals whose DNA has been altered in a laboratory in ways that wouldn’t happen through traditional crossbreeding or in nature. The most common examples are corn, soybeans, and cotton, with over 90 percent of each grown in the United States coming from genetically engineered seeds. These modifications typically give crops specific advantages, like surviving weed-killing sprays or resisting insect damage.
How Genetic Modification Works
Traditional plant breeding works by crossing two related plants and hoping the offspring inherit desirable traits. Genetic engineering skips that lottery. Scientists identify a specific gene that produces a useful trait, then insert it directly into a crop’s DNA using lab techniques. In many cases, the donor gene comes from an entirely different species, like a bacterium or a fish.
One common method borrows a trick from nature. A soil bacterium called Agrobacterium naturally transfers bits of its own DNA into plant cells. Scientists swap the bacterium’s DNA payload with the gene they want to deliver, then let the bacterium do what it does best: inject that genetic material into the plant. The transferred DNA travels into the plant cell’s nucleus and becomes a permanent part of the plant’s genome, passed down to every future generation of that crop.
Another approach uses a device called a gene gun, which physically shoots microscopic gold or tungsten particles coated with DNA into plant cells. It’s less elegant than the bacterial method but works on crops that don’t respond well to Agrobacterium.
The Most Common GMO Traits
The vast majority of GMO crops on the market carry one or both of two traits: insect resistance and herbicide tolerance.
Insect-resistant crops produce their own built-in pesticide. Scientists took a gene from a common soil bacterium called Bacillus thuringiensis (Bt) and inserted it into crops like corn and cotton. The gene makes the plant produce proteins that punch holes in the gut lining of specific caterpillars and beetles when they eat the plant. These proteins are highly targeted. They bind to receptors found only in certain insect digestive systems, which is why they don’t affect humans, birds, or most other animals. In 2025, 87 percent of U.S. corn acres carry this Bt trait.
Herbicide-tolerant crops solve a different problem. Farmers need to kill weeds without killing their crop. The most widely planted herbicide-tolerant crops carry a gene from a soil microbe that produces a version of a key plant enzyme the herbicide can’t disable. When the herbicide is sprayed, weeds die because their version of the enzyme gets blocked, shutting down their ability to make essential amino acids. The crop survives because its borrowed enzyme keeps working. Currently, 96 percent of U.S. soybean acres and 92 percent of corn acres are herbicide-tolerant varieties. Many crops are “stacked,” carrying both insect resistance and herbicide tolerance in the same seed.
GMOs Beyond Pest Control
Not all genetic modifications are about protecting crops from bugs and weeds. Some aim to improve nutrition. Golden Rice is engineered to produce beta-carotene, the orange pigment your body converts into vitamin A, in the white part of the grain where it normally doesn’t exist. Scientists inserted genes that build the biochemical pathway for beta-carotene production directly in the rice kernel. The goal is to address vitamin A deficiency, which causes blindness and immune problems in parts of the world where rice is a dietary staple.
The first genetically engineered animal approved for food is a salmon. AquAdvantage Salmon contains a growth hormone gene from Chinook salmon paired with a genetic switch from ocean pout, a cold-water fish. This combination keeps the growth hormone active year-round instead of only during warm months, so the salmon reaches market size faster than conventional farm-raised Atlantic salmon. It’s required to carry a bioengineered label in the U.S.
Other GMO crops currently on the market include varieties of papaya engineered to resist a devastating virus, potatoes that produce less of a potentially harmful compound when fried, and apples that don’t brown when sliced.
Gene Editing vs. Traditional GMOs
A newer technique called CRISPR is changing the conversation about genetic modification. Traditional genetic engineering inserts DNA from a different species into a crop’s genome at a random location. CRISPR works more like a find-and-replace tool: it cuts the plant’s existing DNA at a precise spot and lets the cell’s own repair machinery make small changes. The result can be a crop with an improved version of its own gene, with no foreign DNA left behind.
This distinction matters for regulation. Because CRISPR-edited plants can end up with changes identical to what might occur through natural mutation or conventional breeding, many countries are starting to regulate them differently from traditional GMOs. They tend to move through development faster, face fewer regulatory hurdles, and in many jurisdictions don’t require GMO labeling.
How GMO Foods Are Evaluated for Safety
GMO foods go through safety assessments before reaching the market. These evaluations look at whether the modification introduces anything toxic, whether the new protein could trigger allergic reactions, whether the inserted gene remains stable over generations, and whether the nutritional profile has changed in unexpected ways.
In the U.S., three federal agencies share oversight. The USDA evaluates whether a GMO crop poses risks to other plants or agriculture. The EPA regulates crops that produce their own pesticides, like Bt corn. The FDA assesses whether the food is safe to eat. The World Health Organization’s position is that GMO foods currently on the international market have passed safety assessments and are not likely to present risks for human health. The WHO also notes that no health effects have been demonstrated in the general population of countries where these foods have been approved.
How to Identify GMO Foods
Since January 2022, the U.S. National Bioengineered Food Disclosure Standard has required food manufacturers, importers, and certain retailers to disclose when a product contains bioengineered ingredients. Companies can meet this requirement several ways: printed text on the package, a circular green symbol with the letters “BE,” a QR code or digital link, or a text-message number you can use to request the information.
The standard only covers foods with detectable modified genetic material. Highly processed ingredients like refined oils and sugars derived from GMO crops often contain no detectable modified DNA after processing, so they may not carry the disclosure even though the source crop was genetically engineered. Small food manufacturers have additional options, including phone numbers and web addresses, to share this information.
If you’re looking to avoid GMOs entirely, products certified as USDA Organic cannot intentionally use genetically engineered ingredients. The Non-GMO Project Verified label is another third-party certification that tests products against specific thresholds for GMO content.