Food allergies are a serious concern. Researchers have estimated that some 15 million Americans have some kind of food allergy. Eight foods account for 90 percent of the reported allergies – milk, eggs, peanuts, tree nuts, soy, wheat, fish, and shellfish. And for some people, food allergies can be fatal.
Some reports in online and popular magazines have suggested that the allergenicity rate has increased since the introduction of GM crops. There is no evidence to link allergenicity to currently authorized GM crops. In fact, food allergies have increased in all industrialized countries, including those where GM crops are not approved.
One is an increased interest in food allergies. Unfortunately, there are no stable diagnostic criteria for testing for food allergies and food intolerance. Together, these two factors have probably resulted in an increase in reporting of allergies. Therefore, rates of allergies may not have actually increased as much as it would appear.
A second cause is that increased prevalence of allergies is in some cases well documented. These are likely due to the fact that the consumption of some foods has increased in certain geographic areas. For instance, in the U.S., the use of soy-based infant formula has increased in the last 10-20 years. You need to be exposed to a substance to develop an allergy to it, and historically not as many people had been exposed to soy, particularly as infants, as they are today. Any increase in infant soy allergies is likely due to increased consumption of soy.
Third, better household hygiene and reduced early exposure to allergens and infections may be partially responsible for increasing rates of some allergies. This has been called the “hygiene hypothesis.” Because exposure to certain allergens is removed or greatly reduced during infancy and early childhood, the immune systems may develop an improper or exaggerated response, resulting in allergies later in life. Supporting evidence for this theory includes the fact that children on farms have lower rates of asthma than non-farm children, and children born into a household with a pet are also less likely to develop asthma than children in a home where a pet is introduced later in life.
According to Dr. Wesley Burks, Chairman of the Department of Pediatrics at the University of North Carolina Medical School and Physician in Chief of the North Carolina Children’s Hospital and president of the American Academy of Allergy, Asthma and Immunology (AAAAI), “Allergic disease truly has changed in the last 20 to 30 years. There are lots of reasons that we all speculate about why it’s different. There’s a hygiene hypothesis, that we live in too clean a lifestyle. There are the changes in our gastrointestinal system, the actual microbiome, that happened over time. There are changes in our environment, the air that we breathe, for diesel particulate exhaust.
“Those three areas are much, much, much more likely to have a part in the change of allergic disease than anything related to food biotechnology. It’s not even on my list of things that I think about that would have caused those changes because of what I know about the safety and the approval process in the development of these foods. There’s just not a way that they’re going to be related to change more allergic disease.” More from Dr. Burks can be heard here.
Assessing the allergenicity of introduced proteins is a required component of the safety assessment of GM crops. No single test exists that can be used to determine if a substance is an allergen. Consequently, allergenicity must be assessed on a case-by-case basis.
No matter what the source of the gene, every new protein is assessed for certain characteristics to help avoid the introduction of potential allergens into a GM crop. This is done by looking at two aspects of the protein:
- The physicochemical characteristics of the protein. We know that some allergenic proteins share certain physiochemical structures. Where the introduced protein in a GM crop shares such structures, they are subject to additional scrutiny as potential allergens.
- The susceptibility of the introduced protein to digestion. If a protein is quickly digested, it has less likelihood of being able to elicit an allergic reaction. This can be easily tested using enzymes important in protein digestion.
Sources of known allergens, such as nuts or eggs, are generally avoided as gene sources for GM crops. Where the source of a gene is known to contain an allergen, the GM crop is examined critically to determine whether the proteins that are introduced into the GM crop are the same proteins that are allergens in the source. This is done by comparing the protein to lists of known allergens, and by testing with the blood/serum of patients known to be allergic to the gene source.
There are hundreds of thousands of different proteins in the human diet, and only a tiny fraction of these are significant food allergens. Thus, the risk of a new protein being a food allergen is very low. By using a ‘weight of evidence’ approach which considers source, structure and digestibility, the risk of introducing an allergen into GM crops can be reduced to a negligible level.
Nature Biotech Perspectives: “Allergenicity assessment of genetically modified crops—what makes sense?” by Richard E Goodman et al.
European Food Safety Authority (EFSA): “Scientific Opinion on the assessment of allergenicity of GM plants and microorganisms and derived food and feed.”
Allergy and Clinical Immunology: Food Allergens .
American Medical Association: Report on Labeling of Bioengineered Foods.
Scientific American: Allergic to Science – Proteins and Allergens in our Genetically Engineered Food.
Food Allergy Research & Education: Food Allergy Facts and Statistics.