What does it mean for food to be ‘GMO-free’?

The mexican food chain Chipotle recently announced that they have removed genetically engineered ingredients from their menu. The company reported that they will still serve meat and dairy from animals fed on GE feed, and drinks sweetened with GE corn syrup, raising the question of what it really means for food to be ‘GMO-free’. We asked researchers if there was any scientific basis to the concept.


Dr. Alison Van Eenennaam, Animal Geneticist in the Department of Animal Science at the University of California, Davis (webpage):

Expertise: research and education on the use of animal genomics and biotechnology in livestock production system; use of DNA-based biotechnologies in beef cattle production.

“Assuming by GMO we mean the use of genetic engineering in food ingredients, i.e. the use of recombinant DNA technology to move useful genetic variation from one species to another, then the question becomes one of: what do you mean by free? The answer will depend on what food and what ingredients.

“There are approved varieties of genetically engineered corn, soybean, canola, cotton, papaya, alfalfa, sweetcorn, some squash available commercially in the United States. So if you are eating any whole food species (e.g. almonds, oranges, carrots, bananas, tomatoes etc.) other than those listed above then they are ‘GMO-free’ in the sense that genetic engineering was not used in the breeding of the varieties currently on the market. There were most likely other plant breeding methods used in the development of the different varieties of these crops such as radiation mutagenesis or embryo rescue, but not genetic engineering.

“But what about when you are eating a food mixture like say nachos? Then it becomes much more complicated. Most likely the corn chips came from a genetically engineered corn variety, unless it is blue corn which would be ‘GMO-free’ as there are no genetically engineered blue corn varieties. But the chips might have been fried in oil derived from a genetically engineered crop such as canola, though you would not be able to test that oil as ‘GMO-free’ as oil does not contain any DNA or protein, so you would need to know the origin of the oil. If the oil was sunflower then it could be assumed to be ‘GMO-free’, even though it might have been derived from a sunflower variety that was herbicide resistant through conventional breeding and hence sprayed with herbicides.

“The milk for the sour cream in all probability came from cows that had consumed genetically engineered feed, and the cheese was almost certainly clotted using rennet derived from a genetically engineered microbe to separate the curds and the whey. The use of genetic engineering in the production of the cheese as a food processing aid rather than an ingredient does not render the cheese to be considered a ‘GMO’. And genetic engineering was not used in the development of the cow herself, though it is likely that other conventional animal breeding methods such as artificial insemination, genomic selection and embryo transfer were.”


Dr. Ruth MacDonald,  Professor and Chair of the Department of Food Science and Human Nutrition, Iowa State University (webpage):

Expertise: factors in foods that reduce in the incidence or progression of cancer; consumer knowledge of food and nutrition relative to technology.

“All foods, derived from plants, microorganisms or animals, contain DNA and the proteins encoded by them. The DNA or proteins presented to our digestive tracts from foods are broken down by the same enzymes – regardless of how they entered the food. The human digestive tract cannot distinguish GMO-derived DNA or proteins from any other DNA or protein. A GMO-free food contains DNA and proteins and these are handled by the body the same way as the DNA and protein in a GMO food.

“The only way to trace transgenes through the food system is to monitor the source of all ingredients used in the processing system. This requires separation of crops as they are harvested from the fields, through the transportation system, to the ingredient processing facility to the food/feed manufacturer. While this can be done, the cost is substantial because each step requires monitoring, testing, validation and record keeping. Given that there is zero risk to human health from consuming GMO-derived foods, what ethical basis can there be for raising the cost of food unnecessarily?

“When grains are processed to generate the wide range of food ingredients derived from them, most of these products have no trace of DNA or protein that would allow tracking of a transgene in the final product. For example, corn oil derived from GMO corn is chemically identical to corn oil derived from organic corn. Therefore, there is no scientific or health basis to value a non-GMO ingredient over one derived using biotechnology – they are identical. Animals, like humans, breakdown and digest GMO-derived DNA the same way they do any other source of DNA. There is no DNA found in milk, meat or eggs that comes from the grain consumed by the animals.”


Dr. Bruce M. Chassy, Professor Emeritus in the Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign (webpage):

Expertise: Molecular biology and biotechnology of lactic acid bacteria used in food and dairy applications; development of recombinant DNA techniques and HOST-VECTOR systems for the genetic manipulation of food microorganisms.

“As surprising as it may seem given all the media attention, there actually isn’t a legal definition of what is a GMO in the US. There are at least two fundamental reasons for this. The first is that no law has been passed that defines what exactly a GMO is. The second is that virtually all the crops and animals we eat, and the microbes we use to make food ingredients and enzymes, cannot be found as such in nature but have been extensively genetically modified, whether by conventional breeding or in the lab.

“Some are surprised to learn that it’s not only scientists in a laboratory who introduce foreign genes to make GMOs. Evidence is mounting that genes from far distant organisms often transfer into food plants. These so-called natural gene transfers are mediated by the same microorganism which scientists use to transfer genes. The product is a GMO. To a scientist the important question is not how a new trait is introduced into an organism but whether the introduced new trait is safe to consume. Put another way, scientific safety assessment focuses on the safety of the food itself, not on the process used to produce it.

“Before a GMO can be introduced into the food market is must be demonstrated through research that there is no meaningful difference between it and other varieties of the same food crop or animal. It must have similar composition and nutritional value and it must not introduce any new or different risks.

“More than 90% of the US corn, soybean, canola, and cotton crops are GMO varieties. For the most part these crops are not eaten as such but are instead used to feed animals, or produce industrial chemicals and food ingredients like sugar, oils, starch, emulsifiers, lecithin and Vitamin E that are often used in foods. It should not come as a surprise then that more that more than 75% of food products in the US contain some ingredient isolated from a GM plant. It is impossible in many cases to determine if an ingredient came from a GM plant because it is identical to, and indistinguishable from, the same food ingredient isolated from a non-GM plant.”


Dr. Alan McHughen, CE Biotechnology Specialist and Geneticist, University of California, Riverside (webpage):

Expertise:  A molecular geneticist with an interest in crop improvement and environmental sustainability, he helped develop US and Canadian regulations governing the safety of genetically engineered crops and foods.

“There is no scientific means to enforce ‘GE free’ because there is no chemical, physical or biological difference in the vast majority of so-called ‘GE ingredients’ from ‘non-GE ingredients’. For example, sugar from a GE sugarbeet is identical to sugar from a non-GE sugarbeet. Contrary to popular misconception, there is no ‘GMO substance’ present in the foods, and certainly nothing present to cause harm.

“Any food business wishing to remove GE ingredients faces difficulties; In addition to the meat from animals fed on feeds from GE plants, there is the lesser known cheese made with GE chymosin, as well as various vitamins and other ingredients made from GE sources.”


Declared interests (see GENeS register of interests policy):

None declared

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