Hi. How does gmo affect alergens in food?
Submitted by: markoprivatnokukor
Expert response from S. Liza Dunn
Medical Outreach Lead, Bayer
Wednesday, 06/11/2019 18:39
Thank you for your question!
Many people ask if GMOs cause allergies. In order to address this question during the early years of GM development, the FDA decided to evaluate using transgenic methods to introduce DNA in plants because some crops (soy) are allergenic. Therefore, regulatory requirements were established for evaluating the allergenicity of GM crops (EFSA, 2006; CODEX, 2009; Hoekenga et al., 2013). Since 1992, over 1300 separate assessments by regulatory agencies around the world have reviewed safety data on various GM crops and concluded that they are as safe as their conventional counterparts. Twenty years of data on GM crops have shown that applying transgenic methods to plants does not affect the levels of allergenic proteins native to those crops or added any additional allergenic proteins.
GM crops are rigorously assessed for safety before commercialization (EFSA, 2006; CODEX, 2009; Hoekenga et al., 2013). The evaluation includes: 1) the assessment of the whole plant after introduction of the GM trait, and 2) the assessment of the newly expressed GM proteins.
The first query for judging the allergenic potential of the whole GM plant is whether the use of transgenic methods inadvertently increase levels of native allergenic proteins within the plant as a whole and data has shown that applying transgenic methods to plants does not affect the levels of native allergenic proteins and GM crops are as safe as conventionally developed crops.
The second query assesses whether the newly introduced protein has any potential for allergenicity. Newly introduced proteins in GM crops are evaluated using a weight-of-evidence approach that addresses the following questions (Dunn 2017):
- Is the source of the gene a known allergenic food?
- An industry-accepted best practice is to avoid using genes from sources that are known to cause food allergy.
- Does the amino acid sequence of the newly expressed protein have any structural similarity to known allergenic proteins?
- New proteins in GM crops are evaluated using bioinformatic tools to compare the amino acid sequence with sequences of all known human allergens (Silvanovich et al., 2009; Ladics et al., 2011; Goodman et al., 2016). The bioinformatic assessment compares the newly expressed protein with a database of ~2000 known allergens.
- Is the newly expressed protein found in high concentrations in the food?
- The proteins expressed in the grain of GM crops are typically found at concentrations of 0.1 -100 ppm, which is orders of magnitude lower than concentrations of antigens that cause sensitization. (Hammond and Cockburn, 2007).
- Is the expressed protein highly resistant to digestion by pepsin?
- A feature of proteins that increases the likelihood of producing an allergic reaction is resistance to digestion by enzymes of the gastro-intestinal (GI) tract (Astwood et al., 1996; Bannon et al., 2003; Thomas et al., 2004) . Most proteins from the diet are rapidly digested by enzymes, which limits exposure of the gut immune system to potential allergens. Codex guidelines require digestibility testing on newly introduced proteins as part of the safety assessment for GM crops.
This degree of testing on GM crops is not required for either conventional or organic crops. Given the extent of this testing, we as consumers can be confident that the risk of allergy posed by GM crops is no greater than that of their non-GM counterparts.
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Dunn, S.E. et al. 2017. The allergenicity of genetically modified foods from genetically engineered crops. Ann Allergy Asthma Immunol 119: 214-222.
EFSA. 2006. Guidance document for the risk assessment of genetically modified plants and derived food and feed by the Scientific Panel on Genetically Modified Organisms (GMO) - including draft document updated in 2008. EFSA Journal 4: 99.
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