3.7 MYTH:

GM foods are properly tested for ability to cause allergic reactions


No thorough allergenicity testing is conducted on GM foods

“There is more than a casual association between GM foods and adverse health effects…. Multiple animal studies show significant immune dysregulation, including upregulation of cytokines [protein molecules involved in immune responses] associated with asthma, allergy, and inflammation.”
– American Academy of Environmental Medicine101

Most food allergies are caused by a reaction to a protein in a food. The DNA of an organism contains instructions for making proteins. Genetic engineering changes the DNA of a food, and that altered DNA can in turn can create new proteins. Therefore, GM foods could create new allergies in two ways: the new proteins could cause allergic reactions (be “allergens”) themselves, or the new proteins could sensitise people to existing food proteins.

The website GMO Compass, which is run by the public relations firm Genius GmbH, claims that GM plants pose no greater risk than new varieties of crops obtained through conventional breeding, or the importation of new exotic foods, which can also result in new allergens appearing in the diet.102

But independent scientists disagree. A 2003 review states that compared with conventional breeding, GM has a “greater potential to introduce novel proteins into the food supply” and increase the likelihood of allergic reactions.103 This was confirmed by a rare study on humans, in which one of the experimental subjects showed an immune response to GM soy but not to non-GM soy. GM soy was found to contain a protein that was different from the protein in the non-GM variety.63

3.7.1.  The EU system for assessing GM plants for allergenicity

Under European law, GM plants must be assessed for their potential to cause allergies before they are allowed onto the market. Proponents claim that any potentially allergenic GM foods are likely to be caught by these regulatory checks. The GMO Compass website calls these assessments “rigorous” and adds, “If a GM plant is found to contain a potential allergen, its chances of receiving approval in the EU are slim to none.”102,104

But in reality, the European regulatory process, though stronger than the US process, has no rigorous system for assessing the allergenic potential of GM foods. This is largely because reliable scientific tests to predict allergenicity have not been developed.

The process that EU regulators use to assess the allergenicity of GM foods102,105 is based on a system proposed in 2001 by the Food and Agriculture Organisation of the United Nations and the World Health Organisation.106 This system was actually designed by two GM industry-funded groups, the International Life Sciences Institute (ILSI), and the International Food Biotechnology Council (IFBC), as the FAO/WHO freely states.106

The process begins with a comparison of the protein that the GM plant is designed to produce with known allergenic proteins. Depending on the outcome of this initial assessment, further investigations can include:

  • Tests to see if the new protein reacts with the blood serum of sensitive individuals
  • Artificial stomach tests to see if the protein is broken down easily (if it is, it is thought unlikely to be an allergen)
  • Animal feeding trials.102

3.7.2.  Why the allergy assessment process is ineffective

Independent scientists have stated that the EU’s allergenicity assessment is unlikely to reliably predict whether a GM food is likely to cause allergic reactions.

The most important reason is that the new protein that is assessed in the regulatory process is normally not the protein as expressed in the whole GM plant. Instead, it is what is known as a surrogate protein. This surrogate protein is isolated from sources such as GM E. coli bacteria or, occasionally, a different plant species.107 This is scientifically unjustifiable because the protein can change as a result of the genetic engineering process and according to the organism within which it is expressed (see 3.1.1 and 3.5.1: StarLink maize). In other words, the same GM gene introduced into a GM plant and into E. coli bacteria can produce proteins that can have very different effects on the people and animals that eat them. In particular, bacteria and plants process newly synthesized proteins in different ways. So even though the amino acid sequences of the two proteins may be identical, their functions can be quite different.

Other reasons why the allergenicity decision tree model is unsatisfactory include:

  • A comparison of the new protein in the GM food with the database of known allergens may not detect new allergens.
  • Blood serum tests are problematic because allergenic sensitization is an allergen-specific process. So unless the transgenic protein expressed in the GMO is already a common allergen, there is unlikely to be a single sensitized person in the world whose blood serum would react with it.103
  • Blood serum tests are not useful in detecting uncommon allergens (substances that few people are allergic to).103
  • A phenomenon known as cross-reactivity can make it difficult to identify from blood serum testing which specific protein out of several is the allergen.103
  • The artificial stomach tests carried out for regulatory purposes are performed under unrealistic conditions – levels of acidity and digestive enzymes are much higher than would be present in the digestive systems of individuals that would consume the GMO. This makes it likely that the new GM protein will be broken down into fragments that are too small to be potent allergens. In real life, however, the levels of acidity and digestive enzymes in people’s stomachs vary, according to age, health status, length of time since they ate their last meal, and other factors. One study found that under the standard conditions used in artificial stomach tests, one of the insecticidal proteins commonly present in GM Bt crops was broken down. But when the researchers adjusted the acidity and enzymes to more realistic levels, the insecticidal protein was highly resistant to being broken down. The authors called for regulatory tests to be carried out in “more physiologically relevant” conditions of lower acidity and lower enzyme levels.100

One review concluded that the allergenicity assessment might be useful in assessing GM foods containing a known allergenic protein, but that assessing proteins of unknown allergenicity is “more problematic” and “the predictive value of such an assessment is unknown”.103 A separate review agrees that the standard tests are “not always conclusive”, especially when the organism from which the GM gene is taken has no history of dietary use or has unknown allergenicity.108

The current allergy assessment system is not reliable because it relies heavily on in vitro tests (test-tube tests on non-living systems, such as the blood serum and artificial stomach tests). But unfortunately, an effective alternative does not yet exist. In vivo tests (tests on living organisms such as animals or humans) are useful for detecting nutritional or toxicological effects of foods, but no animal testing methods have yet been established for allergenicity testing of foods.103,108,109,110 Independent scientists have asked for such animal tests to be developed.109,103,108,110

At present, the only reliable approach to assessing the allergenicity of GMOs would be post-commercialisation monitoring under conditions where consumers are clearly informed when they consume the new GMO and are requested to report any adverse effects to designated authorities. Such post-commercialisation assessments are not required in any country. In countries such as the US and Canada, where consumers are not even informed by labelling of the presence of GMOs in the foods they are eating, the likelihood that allergenicity would be linked to a GMO would be extremely low, unless it caused acute allergenicity problems to a large portion of the population.

3.7.3. Studies on GM foods confirm existing allergy assessments are inadequate

Studies on GM foods confirm that current allergy assessments are inadequate to detect new allergens created by the genetic engineering process.

In a study on mice fed GM peas containing an insecticidal protein from beans (see 3.1.1), mice showed antibody immune reactions and allergic-type inflammatory responses to the GM protein and chicken egg white protein when it was fed to them with the GM peas.

The mice did not show antibody immune reactions and allergic-type inflammatory responses to beans that naturally contain the insecticidal protein or to egg white protein when it was fed with the natural insecticidal protein obtained from beans. They also did not have an immune response to the egg white protein when it was fed on its own.

These outcomes show that the GM insecticidal protein made the mice more susceptible to developing allergic-type inflammatory reactions to foods eaten with the GM food. This is called immunological cross-priming.

The results indicated that the reaction of the mice to the GM peas was caused by changes brought about by the genetic engineering process. The normally non-immunogenic and non-allergenic insecticidal protein naturally produced in beans was altered in structure and/or function when engineered into peas, becoming a potent immunogen (substance that produces an immune response) and allergen.4

It is important to note that this study was not required by regulators, but was carried out as part of the developer’s voluntary research programme. The allergenicity of the GM peas would likely not have been spotted by the EU’s screening process because the natural, non-GM version of the bean insecticidal protein is not a known allergen. Because of this, blood serum from sensitised individuals would not have been available for regulatory serum tests.

Overall, the study shows that GM foods can contain new allergens and cause new allergic reactions – and that the GMO’s allergenicity is unlikely to be detected using the current allergy assessment process.

Two other studies confirm the inadequacy of the current allergy assessment process:

  • A study on a commercialised GM insecticidal maize, MON810, showed that the GM plant’s proteins were markedly altered compared with those in the non-GM counterpart. Unexpected changes included the appearance of a new form of the protein zein, a known allergen, which was not present in the non-GM maize variety. A number of other proteins were present in both their natural forms and in truncated and lower molecular mass forms.111 The findings suggest major disruptions in gene structure and function in this GM crop. The EU’s allergy assessment failed to pick up these changes and failed to detect the presence of the newly created allergen.
  • A GM soy variety modified with a gene from Brazil nuts was found to be capable of producing an allergic reaction in people who are allergic to Brazil nuts. The researchers had genetically engineered the Brazil nut gene into the soy in order to increase its nutritional value. When they tested the effect of this GM soy on blood serum from people allergic to Brazil nuts, they found that the serum produced an allergic response to the soy. Through scratch tests on skin, they confirmed that people allergic to Brazil nuts were allergic to the modified soybean.64 This study is often cited by GM proponents as evidence of the effectiveness of regulatory processes in identifying allergenic foods before they reach the marketplace. But this is untrue. Tests such as this are not required to be carried out as part of the regulatory assessment of GM foods in any country.

3.7.4. Conclusion

The absence of reliable methods for allergenicity testing and the lack of rigour in current allergy assessments mean that it is impossible to reliably predict whether a GM crop will prove to be allergenic.

  • For references, please click here.
  • Download a PDF of the full GMO Myths and Truths report
  • We work hard to bring you reports backed up by strong science.
    Please help us by supporting our work.
    Donate button

Add comment

Security code