GMOs – a new problem for allergology?

According to the definition of the World Health Organization (WHO), genetically modified organisms (GMOs) are those whose genetic material has been altered in an unnatural way [1,2]. Transferring selected genes from one organism to another (including between unrelated species) is possible through DNA recombination methods. These methods are also known as genetic engineering techniques [1].

The same methods are used in the production of microorganisms crucial for the pharmaceutical industry. They are utilized, among other applications, in the production of allergenic vaccines [3]. Overall, approximately 250 drugs and vaccines are produced using GMOs, with 100 in the testing phase [7]. The first genetically modified organism was used to produce insulin. Before this, diabetic patients had to rely on insulin from pigs, cattle, or horses [6].

The use of GMOs in medicine generally does not provoke controversy. However, the situation is different when it comes to food [7]. Currently, 12 species of genetically modified plants are cultivated worldwide, primarily soybeans (52% of crops) and maize (31%) [7]. These crops already cover an area of over 200 million hectares, with a significant portion located in the USA, Brazil, and China [10,11].

The majority of highly processed food sold in the USA contains GMO ingredients [10]. The first genetically modified edible crop to be commercially released was the FlavrSavr tomato, introduced to market by the United States in 1994 [10,11]. More recently, genetically modified varieties of salmon have been introduced into the American market. This variety can be raised year-round [10]. Therefore, GMOs are not limited to plant-based food.

Food produced from genetically modified organisms or using them is widely considered harmful, and the technology itself is viewed negatively. GMOs are the cause of protests by many social groups and environmental organizations [7]. In Poland, as in many European countries, GMO cultivation is not allowed. Genetically modified plants like cotton, maize, rapeseed, soybeans, and sugar beets are only cultivated in some European countries [5]. However, there is no ban on importing GMO food and feed in Europe [7].

Labeling Issues

When the GMO content exceeds 0.9%, it is required to be indicated in the product’s ingredients [5,7]. This is particularly important for individuals with allergies, although according to allergists, for the benefit of this consumer group, manufacturers should disclose any amount of GMO present in the product [3]. This would help protect against accidental exposure to food allergens that should not be in a given product.

On food packaging, more often than declarations of genetically modified ingredients, you’ll find statements like “non-GMO” or “GMO-free.” This reflects the fact that food labeling is often influenced by marketing efforts. Providing reliable health-relevant information then becomes secondary.

At one point, “non-GMO” labels even became a marketing strategy designed to encourage consumers to purchase products advertised as natural. Contrary to suggestive advertising, such labels do not confer organic food status to products. Unethical practices have limited recent legal changes in Poland regarding the labeling of “non-GMO” food [8]. However, such marketing efforts have contributed to increased concerns about this type of food. Are these concerns justified?

Safety

The World Health Organization (WHO) maintains that genetically modified food is not more dangerous to health than conventional food [1,2]. Furthermore, it undergoes better control because there are special systems for rigorous assessment of GMO organisms and food, considering both human health and environmental impacts. Similar assessments are generally not conducted for conventional food, even though new varieties of organisms for consumption also arise using traditional breeding methods [1].

Scientists continue to study genetically modified food for potential long-term health consequences that may result from its presence in the diet. They approach the subject with caution, anticipating that the state of knowledge may change unfavorably towards GMOs in the future. This has happened with other types of products initially considered safe [3,9]. However, credible evidence confirming either the harmfulness or, conversely, the benefits of GMOs on a global scale is still lacking [10]. Population-based studies have not been conducted [7].

The most significant health-related issues associated with the impact of GMOs include the risk of cancer, obesity, allergies, and antibiotic resistance [1,3]. Scientists are questioning whether the recent increase in allergic diseases and food intolerances in recent years could be related to the growing presence of GMO foods in the market [3].

Allergenicity

What do we know for certain? Genetic modification can influence allergenicity. However, it’s important to remember that as a rule, the transfer of genes from commonly allergenic organisms to non-allergenic organisms is discouraged [1].

Additionally, all GMO products are tested for allergenicity, as well as the presence of substances potentially harmful to humans [7]. It is possible to predict to some extent, at least theoretically, whether a given protein could be an allergen. One can compare the sequence and structure of its amino acids with the sequence and structure of amino acids comprising known allergens [11]. However, no method can provide 100% certainty that a tested product will not turn out to be allergenic [2,11].

We have already seen scandals involving GMO food that were supposed to lead to severe allergic reactions. In the USA, genetically modified field corn, intended for livestock feed production, also ended up in products meant for human consumption. It was detected, for example, in tortillas. Consuming corn tacos triggered allergy symptoms in some consumers, including the most severe reactions such as anaphylaxis [2,3,11]. Suspicions of allergenic effects were directed towards the new protein Cry9c found in genetically modified Bt corn [11]. However, ultimately, there was a lack of evidence directly linking this protein to the occurrence of allergic reactions [11].

It must be acknowledged that genetically modified food – through appropriate modification – can benefit individuals with food allergies. How so? Take wheat, for example, where genetic engineering has removed 35 out of 45 identified genes responsible for gliadin synthesis. Gliadin is a key component of gluten associated with celiac disease and wheat allergy. As a result, wheat’s immunoreactivity decreased by as much as 85% [4]. Such modified wheat could potentially be used in the future for producing low-gluten food products.

The main allergenic proteins have also been successfully eliminated from carrots, so wheat is not an isolated case [2,3]. Similar work has been carried for example on soya and peanuts [11].

Genetic engineering methods can be used not only to reduce the allergenicity of products but also to increase the content of micronutrients in food (as seen in the case of so-called “golden rice” with high beta-carotene content [10]). Additionally, genetically modified crops can increase yields and help plants better tolerate drought, thrive after irrigation with salty water, or produce fruits and vegetables resistant to mold and rot [10].

However, is GMO really being used on a large scale as we would like it to be used? Unfortunately, the reality looks quite different. Genetic engineering methods are currently mainly used to make crops resistant to chemical herbicides, i.e., weed killers [7,10]. As a result, herbicide use has increased (in the USA, a 250-fold increase was recorded from 1974 to 2014!) [10].

Meanwhile, glyphosate has come under scrutiny by the International Agency for Research on Cancer. This herbicide, widely used in GMO food crop production, is likely carcinogenic to humans [10]. Recently, residues of glyphosate are increasingly detected in food, including products intended for children and even drinking water [10]. This significantly complicates the safety issues related to GMO use.

In addition to health and environmental concerns (not limited to the mentioned herbicides), economic impacts (such as global monopolies on food production) must also be considered, often raised by opponents of GMOs [7]. Allergists also note that changes in ecosystems due to the introduction of GMO crops may affect the presence of pollen allergens in the air [2].

Therefore, the true consequences of mass production of genetically modified food will only become apparent in the future.

Aleksandra Lipiec 

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translation: Julia Majsiak