Understanding the biology behind GMOs can help consumers evaluate GMO safety

What are GMOs and are they safe to eat?

What are GMOs (genetically modified organisms) and are they safe to eat? It can be difficult for a consumer to sort through and understand the information in the media and on food labels regarding food production methods and food safety. When it comes to GMOs, which refer to genetically modified (GM) crops resulting from a modern breeding method called genetic engineering, there is a great deal of information. Some information is accurate, some not, and some misleading. However, according to a Pew survey, there is much agreement among scientists about the safety of GMO plants and products for human consumption.

Based on hundreds of research studies, more than 280 food safety agencies, and scientific and technical institutions throughout the world (Table 1), support the safety of GMO technology (genetic engineering) to modify traits in plants. This includes the Food and Drug Administration (U.S. FDA), the European Food Safety Authority, and the World Health Organization. Despite the scientific consensus on safety, consumer concerns abound. Such concerns often include environmental, agricultural production, economic, and social justice aspects. This article deals specifically with food safety.

Table 1. Some of the 280 organizations that consider Genetic Engineering (GMO) technology and regulation safe.


National Academy of Sciences - May 2016

Society of Toxicology - September 2002 - Consensus position statement

National Research Council - National Academy of Sciences

American Medical Association

Institute of Food Technologists

American Dietetic Association

European and International

France - French Academy of Medicine - 2003

Italy - Eighteen scientific associations - October 2004 (including National Academy of Science, Societies for Toxicology, Microbiology, Nutrition, Biochemistry) signed consensus statement on safety of GMO crops

FAO - Food and Agriculture Organization

WHO - World Health Organization

International Council for Science - 2005, 2010 (111 National Academies of Science and 29 scientific unions)

What is a GMO?     

Some people cringe at the words “genetically modified organism”, but genetic modification is an important method people have used for the past 10,000-30,000 years while they domesticated both crops and animals. When plants and animals are selectively mated, the genes from both parents are mixed and many inherited traits are changed, which can be readily observed in the wide varieties of certain species, such as dog breeds.  Without much knowledge about genetics, plants and animals were purposefully changed when people observed differences in plants and animals, and then mated what appeared to be the “best” ones to create and/or preserve beneficial traits and characteristics. 

Today, several different breeding methods are used to improve plants, including the traditional methods (when possible). Regardless of method, all involve modifying the genetic makeup, or genes, of an organism. All living organisms -plants, animals, microbes- have genes, and all genes are made of DNA (Deoxyribonucleic Acid), which is the universal coding system that determines traits such as crop yield, height, hair color, horns, etc. 

In contrast to a plant created by modifying its DNA using traditional breeding methods, a GMO plant is created using a newer, more controlled method referred to as genetic engineering. This method changes plants by inserting a gene from another organism to add a useful trait to the recipient organism, such as disease or pest resistance. With genetic engineering, the DNA can come from organisms that cannot mate with the crop being modified, e.g., bacteria, fungi or another crop or unrelated plant. For example, one might move a drought tolerant gene from a drought tolerant plant to a corn plant. Since the 1980s, an important GMO is bacteria that have been modified to produce human insulin. These bacteria resulted from inserting the human gene for insulin into the bacteria DNA, so they can produce the human insulin protein. Bacteria produce about 90 percent of human insulin today. 

With genetic engineering, usually only one gene from the donor, with a known role or coding for a known protein, is added or inserted into the current set of genes of a recipient plant. In contrast, traditional breeding methods mix many genes (from similar plants) in the mating process. Further, the resulting plants or offspring could have multiple and/or unpredictable outcomes, some of which can be undesirable (e.g., negative impact on yield, quality, or flavor).

Within the past decade, an even more precise method of genetic engineering has been developed called gene editing. This method simply “edits” the DNA code of a gene in an organism to modify its expression, instead of introducing a new gene, to give the organism certain characteristics such as more drought tolerant or nutritious. Related techniques can also be used to insert a new gene from another organism into a precise location in the organism’s DNA.   

What are Genes and DNA?

Genes provide the instructions for the cells of plants and animals to do their work. Genes are made of units of DNA, represented by the letters A, T, G and C, which form thread-like chains of molecules that look like a twisted ladder (Figure 1). DNA code is similar to the binary code system in computers, which uses “0” and “1” in different arrangements to create messages or computer instructions. With DNA, combinations of A, T, G, and C form each gene and genes code for various proteins (Figure 1). Proteins in plant and animal cells control various functions of the cell and organism.  All methods used to genetically modify plants change DNA, including naturally occurring mutations, resulting in changes in the genetic code. A simple example of a mutation or a change in the code would be changing a G to T. Click here to learn more.     

DNA and Genecell 4 (2)
Figure 1. Genes are made of sequences of DNA which form thread-like chains and code for specific proteins that control cell functions.

 Are Genes and DNA safe to eat? 

Virtually everything we eat comes from a plant, animal, or fungal source.  That means it either has genes (DNA) in it or if it was highly processed, such as oil and sugars which no longer contain DNA, it was extracted from an organism that had genes. This means we are constantly eating genes (DNA), whether modified by traditional breeding methods, natural mutations or genetic engineering. Our digestive tract breaks down DNA in the same way, regardless of the source and regardless of the DNA sequence.  

Nonetheless, proteins produced by the new genes, and the resultant crop products, must be tested for safety. For this reason, whenever a new plant variety is created using genetic engineering in the U.S., the new variety undergoes rigorous testing for allergens, toxins and modified nutritional content, based on FDA and international food safety standards. All GM products currently on the market have been approved by and are regulated by the FDA. For a greater understanding of testing genetic engineered plants, see a discussion by Professor Robert Hollingworth from the Michigan State University Center for Research on Ingredient Safety (CRIS).

Why use GMO Crops? 

All farmers face challenges from insects, disease, weeds and weather in their efforts to cultivate healthy, productive crops. Genetic engineering provides another tool to deal with some of these challenges.

Some examples of traits that have been added to plants using genetic engineering include:

  • Disease resistance
  • Drought resistance
  • Insect resistance
  • Herbicide tolerance
  • Improved nutrition (e.g., adding Vitamin A production in golden rice to prevent deficiencies in third-world countries and increasing protein in cassava)

There are ten crops that have been approved GM varieties in the United States as of 2018:

  • Corn (field and sweet)
  • Soybeans
  • Cotton
  • Alfalfa
  • Sugar beets
  • Canola
  • Papaya
  • Summer squash
  • Innate potatoes
  • Non-browing Arctic apples

In the case of corn, soybeans, cotton, sugar beets, and papaya over 90 percent of the acreage in the U.S. consists of genetically-engineered varieties. Farmers have quickly adopted crops produced by this technology because they reduce losses from pests, and reduce production costs, pesticide use, and the carbon footprint (National Academy of Sciences). For all of the other approved GM crops, only a small proportion is GMO.

Foods in U.S. stores today might contain products from GM corn, soybeans, canola, or sugar beets. However, processed oils or sugars from these crops are refined products and do not contain DNA or proteins.  


The topic of GMOs is very important to many individuals and organizations because it involves questions related to food safety, human health, ecosystem health, and the ability to continue to make genetic improvements of plants. The GMO debate is likely to continue for many years because of the complexity and strong opinions on the topic, as well as the economic impacts that may influence interest groups on both sides of the debate. GMOs continue to be researched, new methods are evolving and with new information, comes new points for discussion.

Understanding some basic biology and the processes of plant breeding can help individuals understand GMOs and their safety. When looking for information, be sure to seek information from institutions and agencies that share science-based, objective results. Several university Extension services are now offering easy-to-use websites for those seeking accessible and reputable information about the safety of GMOs. Michigan State University AgBioResearch devoted an entire issue of its Futures Magazine to: “The Science behind GMOs”. The Food and Drug Administration as well as the World Health Organization also have useful information on GMOs.

Virtually all that we eat today, whether plants or animals, has had its DNA altered by humans for thousands of years. The DNA that is modified consists of the same building blocks (DNA) whether the organism is genetically engineered or not. It is the arrangement of the DNA that makes any altered organism different from another, not if DNA is modified by natural mutation or various breeding methods (traditional breeding methods or genetic engineering).

In a nutshell, genetic engineering in plants is a more recent and more precise method of producing plants with desirable traits. Changing the DNA in plants has no influence on the safety of the DNA because we readily digest the strands of DNA as we always have. The proteins created by the new DNA are tested in accordance with FDA guidelines, to ensure that they are safe to consume.


Learn more:

US Food and Drug Administration (FDA)

The World Health Organization (WHO)

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