GMOs Demystified- Part 2: Health Effects

How do you know if it's GMO? Are GMO foods safe?

How do you know if it’s GMO? Are GM foods safe?

Rural System, above all else, is an approach to land management that emphasizes reasonableness in making management decisions. “How much profit can be made?” is balanced with “How long will profit be made?” “What’s good for humans?” is balanced with “What is good for the ecosystem?” All management decisions are made according to the most recent scientific knowledge on the topic.

The debate over genetically modified food has been extensive and multi-faceted. Like many sensationalized issues, it can be difficult to sort out truth from bias. The series of posts before you is a guide to GMOs based on available science rather than uninformed opinion. Our second question: how do GMOs affect your health when consumed? Are they safe?

To answer the question under the photo, an estimated 80% of all processed foods contain GM ingredients. Some tomatoes are engineered to retain flavor, papayas from Hawaii are frequently engineered, along with sweet corn and yellow and zucchini squash. So are GM foods safe? What concerns do people have?

Once concern is that there is not enough evidence or a long enough history behind GM products for us to know they are safe. We know that the first product was available for widespread use in 1982. Is 21 years enough to evaluate long-term effects? We can say that based on the precision of the genetic engineering process and the wealth of research behind it, it is unlikely that it the process is inherently detrimental to peoples’ health. In fact, the widespread use of genetically engineered human insulin has shown that it can be quite beneficial. However, each new application of genetic engineering techniques results in a different product so even if the technique is safe, the product may not be.

“Because only a well-characterized segment of DNA is transferred, biotechnology-based breeding is considered to be more precise than conventional breeding,which involves many uncharacterized linked genes.” – Johns Hopkins publication linked below. Also, see this article.

Of course, like any product intended for human consumption, genetically modified plants and products are tested before they are declared safe. There are three government organizations in charge of regulating the risks of genetically modified organisms on people and on the environment: the EPA, the USDA, and the FDA. A detailed article from Johns Hopkins Bloomberg School of Public Health examines the legislation and procedures in place to help protect consumers and the general environment from hazardous applications of genetic engineering technology. Their study examines the regulatory history of Starlink corn and how regulation of GM products could be improved.

In the case of Starlink corn, traces of GM corn not approved for human consumption were found in commercial products like taco shells. The EPA considered a protein in the GM corn to be of moderate concern as an allergen, so it was only approved for use as animal feed. Its registration for use only as animal feed included a specified buffer of 660 sq. ft. between Starlink corn and other growing corn, but the contamination of other corn varieties with the Starlink proteins suggests that this may not have been enough to prevent cross-pollination. The products were voluntarily recalled by Aventis (the producers of Starlink) after a consumer group, Friends of the Earth, discovered Starlink corn in consumer products.

As you know, there is risk for new allergens in all food products, not only GM products. This Oxford publication explains that predicting the likelihood a protein will be an allergen is extremely difficult with limited accuracy.

“Assessment of exposure to food allergens is particularly challenging, in that adverse events are the result of a biphasic process. In the first phase, the immune system encounters the allergen and becomes capable of responding to it (sensitization). Later, the sensitized immune system encounters the allergen and allergic reaction is triggered” – Johns Hopkins publication linked above.

The World Health Organization has developed a decision tree to estimate a protein’s risk level for being an allergen. The tree consists of a series of questions about the protein’s characteristics, such as its DNA sequence relationship to known allergens or how fast it breaks down in the stomach. One case, where soybeans were engineered to include a tree nut protein high in methionine (an essential amino acid), the soybeans never made it to production because the protein added to the plant was suspected of being a high-risk human allergen. Soybean proteins are already high-risk allergens, so scientists have now engineered hypoallergenic varieties of soybeans instead.

Gregory Jaffe, with the Washington-based consumer group the Center for Science in the Public Interest, has a balanced perspective on the controversy. He points out that it, “has become an ‘us versus them’ type of thing. You have proponents on one side who talk in generalities, who say this is safe, it’s beneficial. And you have opponents on the other side who say it’s not safe and not beneficial. And the reality is you need to look at each specific application.”

We know there is a high likelihood that the genetic engineering process itself isn’t harmful, but we cannot say that every application/use of the technology is perfectly safe without extensive testing. We must proceed cautiously with testing each new organism, and watch closely to prevent environmental damage or risks to human health.

There is plenty of information on the GMO controversy, but it is much easier to navigate with a guide. Coming up next: discover the environmental impact of GM crops.

Read the whole series, or pick a topic that interests you:

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About Laurel Sindewald

Laurel is an alumna of Warren Wilson College with a BS in Conservation Biology and a BA in Philosophy. She is a writer for Rural System, Inc.


  1. Happy to see this post. This is one of my major pet peeves. The law shloud require standard labeling. If there is a chance a food “may contain” an allergen-say so. If it’s same equipment, say so! check out my

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