The Lowdown On GMOs

GMOs — should they be allowed and should they be labeled? While government agencies and scientists claim GMOs are safe, controversy still surrounds this hot topic.

Here’s what you need to know.

What are GMOs?

GMOs — or genetically modified organisms — are plants, animals or microorganisms whose genetic material (DNA) has been changed in a way that cannot occur spontaneously in nature. Genetic-engineering techniques allow scientists to insert genes from one species into another species in order to improve certain attributes.

For example, a segment of DNA from a bacterium that provides insect resistance can be inserted into a corn plant so that the corn also becomes resistant to insects. Therefore, less insecticide needs to be used.

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In genetically modified (GM) plants, scientists typically aim to improve drought tolerance, decrease the need for pesticides and strengthen resistance against plant diseases. Ultimately, the goals are to increase crop yield and quality. A food product made from GMOs is referred to as a GM food.

What are common GM foods?

The following are common, commercially available GM crops, along with their modified traits:

*The Food and Drug Administration (FDA) approved GM salmon in November 2015. This is the first GM animal approved for sale in this country. The FDA stated it rigorously evaluated extensive data and determined the salmon is safe to eat.

What are advantages of GMOs and GM foods?

GM foods can increase food production and provide supplemental nutrition. Here’s how:

  • Decreased pesticide use: Scientists can insert a gene (originally from a soil bacteria that produces a toxin that is lethal to insect larvae) into the DNA of corn and other crops. This enables the plant to produce that same toxin so that it is also protected from insects. Thus, the GM crop requires lower amounts of pesticides.
  • Resistance to plant viruses: Seeds can be genetically modified to make them resistant to plant viruses, which results in higher crop yields.
  • Weather-tolerant crops: GM crops can survive longer periods of cold and drought compared to conventional crops. This allows farmers to increase production, despite harsh conditions. One example — an anti-freeze gene from fish has been inserted into tomato plants to help the plants resist frostbite.
  • Fortified nutritional content: Scientists have created a strain of rice fortified with vitamin A, as well as a type of cassava root fortified with vitamins, minerals and protein. These crops have the potential to combat malnutrition in developing countries where people rely on those crops as the staple of their diets.

How do GMOs affect the environment?

  • Resistant pests: There is a concern that GM crops could cause pests and weeds to evolve into insecticide- and herbicide-resistant “superbugs” and “superweeds” that can no longer be eliminated by chemical sprays. This resistance would render insecticides and herbicides useless, which could harm conventional crops.
  • Introduction of gene into wild plants and animals: While this has not been thoroughly researched, there is concern that GMOs could escape agricultural fields and introduce the engineered gene into wild plants or animals in the surrounding habitat.
  • Species shifts: If an insect-resistant crop causes the extinction of a particular bug, other insects may come and occupy the area, shifting natural populations and causing new pest problems.

What are the potential concerns for human health?

  • Gene transfer: There is some evidence that genes can transfer from GM foods to bacteria in our digestive tract. This would be concerning if these genes are detrimental our health, like if antibiotic-resistant genes were transferred. However, the chance of gene transfer from GMOs to gut bacteria is extremely low — research has shown that the chance of gene transfer from GM crops is lower than the chance of gene transfer that happens randomly when we eat conventional foods.
  • Allergenicity: People are concerned that genes from commonly allergenic foods (like nuts) could be transferred to non-allergenic foods, increasing the risk of allergic reactions. However, this practice is discouraged by the World Health Organization, and currently no GM foods have been found to cause allergic reactions.
  • Links to diseases: There are a few studies that have linked GM foods to inflammation or tumor growth in animals or in test tubes. However, most of those studies are highly flawed and were not published in prestigious scientific journals, as they were not peer-reviewed, lacked scientific rigor and were written by researchers affiliated with anti-GMO organizations.

Are GM foods safe to eat? Reviews of more than 1,500 studies on GMO safety have shown little to no evidence of harm. In addition, organizations such as the American Medical Association, the U.S. National Academy of Sciences and the World Health Organization have analyzed the scientific evidence and have concluded that GM foods do not pose more risks to humans, animals or the environment, compared with conventional foods.

  • Before they become commercially available, GM foods are studied and tested more rigorously than other agricultural products.
  • Research has shown GM plants are nutritionally equivalent to their non-GM counterparts (unless the GM food has been enhanced for nutritional improvement, as in vitamin-A enriched rice or soybeans with more healthy monounsaturated fats).
  • Studies have shown that GM genes are not found in any organ or tissue samples from animals fed GM plants. A study of long-term consequences of GMO consumption in animals — up to five generations — found no evidence of harm.
  • The current scientific literature has not shown GM foods to cause any new allergies, cancers, ADHD, infertility or other diseases.
  • There are no studies on the long-term health effects of GM foods in humans — GM crops weren’t widely approved until the 1990s. The studies that do exist (lasting between 90 days and two years) have not suggested any health hazards.

Can a food be both GM and organic?

Foods that have the USDA organic label cannot be made with GMO ingredients.

What are the current laws about GM foods?

In California, there is no requirement to label GMO-containing foods. Several states have labeling laws, but there is no national consensus on labeling. Some companies have chosen to include a “non-GMO” label on their products. GMO labeling is required in 64 countries due to consumer demands.


GM crops have enabled farmers to efficiently increase crop yield or food quality. While there are concerns about the effects of GM plants on the surrounding environment, from a nutritional standpoint, studies have shown that GM foods are nutritionally equivalent to conventional foods.

Processed meats, which often contain (and are sometimes confused with) GMOs, have been linked to colorectal cancer, according to research done at Keck School of Medicine of USC. It should be noted that choosing non-GMO processed meats does not alleviate the risk, as the issue is with the processing of the meat, not whether or not it has been genetically modified.

There is a need for more research in this field, but the existing evidence suggests that GM foods are safe for human consumption. Ultimately, though, whether to consume GM foods is a personal choice.

Need help putting together a diet plan? Schedule an appointment with your primary care physician.

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By Leanna Tu