---
title: "Genetically modified food controversies"
chunk: 7/21
source: "https://en.wikipedia.org/wiki/Genetically_modified_food_controversies"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:17:47.717639+00:00"
instance: "kb-cron"
---

=== Allergenicity ===
A well-known risk of genetic modification is the introduction of an allergen. Allergen testing is routine for products intended for food, and passing those tests is part of the regulatory requirements. Organizations such as the European Green Party and Greenpeace emphasize this risk. The use of genes from known allergenic sources is discouraged in the research and development of GM foods. A 2005 review of the results from allergen testing stated that "no biotech proteins in foods have been documented to cause allergic reactions". Regulatory authorities require that new modified foods be tested for allergenicity before they are marketed. The Codex Alimentarius recommends a weight-of-evidence safety approach for assessing the allergenic potential of genetically modified crops, including the history of exposure and safety of the source of the inserted gene, the structure of the protein, its stability to pepsin digestion, and the degree of exposure in the gastrointestinal tract as a function of the abundance of the recombinant protein in the food.
In the assessment of the allergenic safety of genetically modified organisms, bioinformatics is used to analyze whether newly expressed proteins show similarity to known human allergens. This process is based on comparing the amino acid sequences of the introduced proteins with specialized allergen databases, allowing verification of whether the protein corresponds to a previously characterized allergen or presents potential for cross-reactivity, i.e., whether its structure is sufficiently similar to that of a known allergen to be recognized by the same IgE antibodies in already sensitized individuals.
The risk that an expressed protein may sensitize human populations and become a new food allergen is assessed on the basis of biochemical and physical aspects, particularly resistance to pepsin digestion and the level of expression in the genetically modified food. Proteins that persist longer during digestion are more likely to expose the gastrointestinal immune system in ways that may trigger allergic reactions. Although resistance to digestion alone does not allow a protein to be classified as allergenic, there is a non-absolute relationship between greater stability in the gastrointestinal tract and a higher likelihood of immune system sensitization. Proteins expressed in commercially available genetically modified crops are present at very low levels and are rapidly degraded.
Dunn et al. (2017) analyzed 83 studies that compared genetically modified foods with their conventional counterparts to determine whether they were more allergenic. No studies in humans or animals were found showing that a genetically modified food is more allergenic than its conventional equivalent.
GMO proponents note that because of the safety testing requirements, the risk of introducing a plant variety with a new allergen or toxin is much smaller than from traditional breeding processes, which do not require such tests. Genetic engineering can have less impact on the expression of genomes or on protein and metabolite levels than conventional breeding or (non-directed) plant mutagenesis. Toxicologists note that "conventional food is not risk-free; allergies occur with many known and even new conventional foods. For example, the kiwi fruit was introduced into the U.S. and the European markets in the 1960s with no known human allergies; however, today there are people allergic to this fruit."
Genetic modification can also be used to remove allergens from foods, potentially reducing the risk of food allergies. A hypo-allergenic strain of soybean was tested in 2003 and shown to lack the major allergen that is found in the beans. A similar approach has been tried in ryegrass, which produces pollen that is a major cause of hay fever: here a fertile GM grass was produced that lacked the main pollen allergen, demonstrating that hypoallergenic grass is also possible.
The development of genetically modified products found to cause allergic reactions has been halted by the companies developing them before they were brought to market. In the early 1990s, Pioneer Hi-Bred attempted to improve the nutrition content of soybeans intended for animal feed by adding a gene from the Brazil nut. Because they knew that people have allergies to nuts, Pioneer ran in vitro and skin prick allergy tests. The tests showed that the transgenic soy was allergenic. Pioneer Hi-Bred therefore discontinued further development. In 2005, a pest-resistant field pea developed by the Australian Commonwealth Scientific and Industrial Research Organisation for use as a pasture crop was shown to cause an allergic reaction in mice. Work on this variety was immediately halted. These cases have been used as evidence that genetic modification can produce unexpected and dangerous changes in foods, and as evidence that safety tests effectively protect the food supply.
During the Starlink corn recalls in 2000, a variety of GM maize containing the Bacillus thuringiensis (Bt) protein Cry9C, was found contaminating corn products in U.S. supermarkets and restaurants. It was also found in Japan and South Korea. Starlink corn had only been approved for animal feed as the Cry9C protein lasts longer in the digestive system than other Bt proteins raising concerns about its potential allergenicity. In 2000, Taco Bell-branded taco shells sold in supermarkets were found to contain Starlink, resulting in a recall of those products, and eventually led to the recall of over 300 products. Sales of StarLink seed were discontinued and the registration for the Starlink varieties was voluntarily withdrawn by Aventis in October 2000. Aid sent by the United Nations and the United States to Central African nations was also found to be contaminated with StarLink corn and the aid was rejected. The U.S. corn supply has been monitored for Starlink Bt proteins since 2001 and no positive samples have been found since 2004. In response, GeneWatch UK and Greenpeace set up the GM Contamination Register in 2005. During the recall, the United States Centers for Disease Control evaluated reports of allergic reactions to StarLink corn, and determined that no allergic reactions to the corn had occurred.