What Are GMOs, Really?



You likely have an opinion about Genetically Modified Organisms (GMOs), either based on little tidbits of information collected online or by experiencing a gut reaction to the concept.  After researching the topic with my middle schooler, I realized that I had a lot to learn about GMOs. Admittedly, my feelings about GMOs did change after helping her complete the project. I have since become more concerned about the potential allergenic effects of GMOs. 

What is a GMO?

Genetically modified organisms are plants, animals, or microbial genes that have had their genetic material changed using genetic engineering. GMOs result from changing DNA structure within an organism, or by transplanting genetic material from another organism, known as transgenic engineering.  Not all GMOs are transgenic, but all transgenic organisms are classified as GMOs.  The World Health Organization defines GMOs as being changed in a way that “does not occur naturally,” as historically was done through hybridization, breeding, or selection (1).

How are GMOs made?

GMO’s are made by changing an organism’s DNA, ideally to create more favorable traits. For example, it’s theorized that Roundup-ready and pesticide-resistant GMO crops allow fewer chemicals to be sprayed than conventional crops.  The four basic steps to creating GMOs are the following (2):

  • Decide on the trait to be changed
  • Find the exact genetic trait to modify
  • Insert the trait into the new genome, using the “gene gun” into the seed or bacterium (Agrobacterium tumefaciens) introduction methods
  • Grow the GMO

Examples of Changes to GMO Foods (3,4,5,6):


  • Bacillus thuringiensis (Bt) spores from a soil bacterium with crystal (Cry) proteins to kill specific insects
  • Agrobacterium sp. strain CP4 glyphosate-resistant enzymes to help kill weeds and not the plant with glyphosate (Roundup) application
  • Drought-resistant enzymes to reduce water need


  • Growth hormone from another fish to make the salmon grow bigger
  • Antifreeze protein to help the salmon live in temperatures below freezing

Sugar Beet:

  • Agrobacterium sp. strain CP4 glyphosate-resistant enzymes to help kill weeds and not the plant with glyphosate (Roundup) application

GMO History and Crop Production1992 to 2013

In 1992, Flavr Savr tomatoes were the first GM crops approved by the USDA.  In 1995, the first insecticide-resistant crop was approved by the FDA.  In 1996, the first Bt corn crop was approved by the FDA (7). As of 2013, the US designates more land for GM crops than any other country, approximately 40% of the world’s GM crops (8). “The US continued to be the lead country with 70.1 million hectares, with an average ~90% adoption across all crops” (9).

Top US GMO crops disclosed as of 2013 (10):

  •     96% of cotton crops are GMO
  •     95% of sugar beet crops are GMO
  •     94% of soybean crops are GMO
  •     93% of corn crops are GMO
  •     90% of canola crops are GMO
  •     50% of papaya crops are GMO
  •     30% of alfalfa crops are GMO
  •     12% of summer squash crops are GMO

Wide-scale, commercially-grown GMO wheat has not yet been reported (11). However, in 2016, 22 “unapproved” GMO wheat plants were identified by the FDA in Washington state alone (12).

Concerns about GMOs:

There are numerous environmental, socioeconomic, and health concerns regarding GMOs (13). Environmental concerns consist of lack of crop diversity and possible impact to pollinators and eventual food supply (14). Socioeconomic concerns reflect negative impact to farmers and lower-income individuals exposed disproportionately to more processed-food GMOs than higher income Americans. Many health concerns revolve around uncertainty about the impact to the gut microbiome and overall health in humans, in part because of minimal epidemiological and longitudinal studies completed. Here are just a few of the concerns that may affect consumers:

  • Although GMOs were approved in the US in 1992, the US has never required national GMO labeling for consumer disclosure, while other countries require labeling. Labeling gives consumers a choice.
  • According to the Centers for Disease Control (CDC), food allergies among US children have increased by 18% between 1997 and 2007 (15). No data has been released since 2008.
  • Lack of GMO labeling in the US may create a public safety issue. Individuals with food allergies are allergic to the proteins in specific foods. If the proteins have been altered, particularly via a transgenic method, individuals will not be able to completely avoid the allergen or quickly identify the cause of an allergic reaction without appropriate labeling.
  • The insecticide Bacillus thuringiensis (Bt) has been linked to allergic reactions. In 2000, a California resident went into anaphylactic shock after eating corn tacos that contained a pest-repelling protein called Cry9C (16).
  • In 2015, the World Health Organization (WHO) listed the herbicide glyphosate (used with conventional non-GMO and GMO Roundup-ready crops) as a “possible carcinogen,” potentially contributing to the development of cancer (17). The WHO later modified their statement in 2016 to indicate that “acceptable daily intakes (ADI)” for maximum residue limits should be established by individual governments to ensure that the biological burden is not exceeded (18).

Now, what are your thoughts about GMOs – friend or foe? Should labeling be required?

Author: Laura Farnsworth, MS, CNS, CN, Integrative & Functional Nutritionist at Craving4Health.com


(1,13) World Health Organization (WHO). (2014), Frequently asked questions on GMO. http://www.who.int/foodsafety/areas_work/food-technology/faq-genetically-modified-food/en/

(2) Powell, C. (2015). How to make a GMO. Genetically Modified Organisms and Our Food. Harvard University. http://sitn.hms.harvard.edu/flash/2015/how-to-make-a-gmo/

(3,7,10) Byrne, T. (2014). Genetically Modified crops: Techniques and applications. Colorado State University. http://extension.colostate.edu/topic-areas/agriculture/genetically-modified-gm-crops-techniques-and-applications-0-710/

(4) Funke, T., Han, H., Healy-Fried, M. L., Fischer, M., & Schönbrunn, E. (2006). Molecular basis for the herbicide resistance of Roundup Ready crops. Proceedings of the National Academy of Sciences, 103(35), 13010-13015. http://www.pnas.org/content/103/35/13010

(5) Rack, J. (2015). NPR. Genetically modified salmon: Coming to a river near you?.


(6) Niederhuber, M. (2015). Insecticidal plants: The tech and safety of GM Bt crops. Genetically Modified Organisms and Our Food. Harvard University. http://sitn.hms.harvard.edu/flash/2015/insecticidal-plants/

(8) Rangel, G. (2015). From corgis to corn: A brief look at the long history of GMO technology. Genetically Modified Organisms and Our Food. Harvard University. http://sitn.hms.harvard.edu/flash/2015/from-corgis-to-corn-a-brief-look-at-the-long-history-of-gmo-technology/

(9) Clive, J. (2013). Global status of commercialized biotech/GM crops: 2013. ISAAA Brief, No. 46. ISAAA: Ithaca, NY.

(11) Charles, D. (2014). GMO wheat investigation closed, but another one opens. NPR. https://www.npr.org/sections/thesalt/2014/09/26/351785294/gmo-wheat-investigation-closed-but-another-one-opens

 (12) Plume, K. (2016). USDA confirms unapproved GMO wheat found in Washington state.


 (14) Gewin, V. (2003). Genetically modified corn—Environmental benefits and risks. PLoS biology, 1(1), e8. http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0000008

 (15) Centers for Disease Control (CDC). (2008). Food allergy among U.S. children: Trends in prevalence and hospitalizations. https://www.cdc.gov/nchs/data/databriefs/db10.pdf

(16) Xu, C. (2015). Nothing to sneeze at: The allergenicity of GMOs. Genetically Modified Organisms and Our Food. Harvard University. http://sitn.hms.harvard.edu/flash/2015/allergies-and-gmos/

 (17) World Health Organization (WHO). (2015). IARC Monographs Volume 112: Evaluation of five organophosphate insecticides and herbicides. https://www.iarc.fr/en/media-centre/iarcnews/pdf/MonographVolume112.pdf

 (18) World Health Organization (WHO). (2016). Food safety: Frequently asked questions. http://www.who.int/foodsafety/faq/en/

blog posts