What are food allergens?



Authored by Rosa Pilolli (ISPA-CNR)


Food allergens are ingredients or substances that may represent a safety risk for sensitized and genetically predisposed individuals upon ingestion.

Food allergies may occur when the ingested allergen triggers a cascade of adverse reactions of the immune system mediated by antibodies or cells. The antibody mediated reactions are the most common and involve two main phases: (i) the sensitization generated at the first exposure to the allergen, (ii) the allergic reactions that occur upon a new exposure of the sensitized individual to the specific allergen. The sensitization activates the immune system by recognizing the offending protein and inducing the production of specific immunoglobulin E (IgE) antibodies. After that, the allergic reaction may occur upon ingestion whenever the specific IgE antibodies link the offending proteins activating the histamine release.

The allergic reactions can range from mild to severe. In some severe cases, allergies can trigger a life-threatening reaction known as anaphylaxis.



The occurrence of allergens in foods represent a new food safety issue with increasing relevance in the last three decades, because of the epidemiologic spread of allergic syndromes and the potential severity that the immunological reactions may present upon ingestion of even tiny amount the offending foods.

The threat for the sensitized allergic consumer raises from the risk of ingestion of commodities where the occurrence of allergenic foods is not declared in the relevant labelling. According to the notifications reported on the Rapid Alert System for Food and Feed (https://webgate.ec.europa.eu/rasff-window/portal/?event=searchForm&cleanSearch=1) during the last five years (2016-2020), the number of alerts with serious risk decision concerning the undeclared presence of food allergens has increased up to 649 notifications (see figure below for alerts distribution in different food categories).




The prevalence of food allergies has been steadily increasing over the past decade, and it currently affects 2-4% of the population although it is not easy to collect clear epidemiological data. The prevalence reaches a maximum during the childhood (6-8%) and is often caused by milk, peanut eggs, fish and crustaceans. Many children growing up manage to overcome their allergy to milk, eggs, cereals and soy during the first ten years, while allergies to peanuts, nuts, fish, and crustaceans usually persist throughout life. Milk and egg allergy are the most common worldwide in children under 4 years old, while peanut allergy is particularly prevalent in the USA, Canada, the United States and the United Kingdom.



Currently, the only solution to prevent adverse reactions in allergic people is to avoid the intake of the offending foods. In order to comply with this dietary prescription, allergic consumers rely on the availability and accuracy of the information provided on pre-packaged and unpackaged foods, hence the need at European Commission level to provide appropriate labelling regulation.


EU regulation on food allergen labelling

Potentially, more than 150 foods are verified to be implicated in allergic reactions, however most cases (more than 90%) can be ascribed to a very small number of ingredients. In 1995, the Food and Agriculture Organization of the United Nations (FAO) has identified eight major allergenic ingredients as the most common causes of allergies in the world following a technical consultation. These foods are identified as the "big eight" for their public health relevance and include milk, egg, grains, soy, peanuts, nuts, and fish. These foods have been included in the list of priority allergens by the International Codex Alimentarius and have provided in the following years the basis for developing a specific regulation on labelling different from country to country.

In this perspective, the European Commission resulted to be the most restrictive worldwide by issuing with the Directive 2007/68/EC (EUR-Lex - 32007L0068 - EN - EUR-Lex (europa.eu)) a list of 14 allergenic ingredients whose presence needs to be specified on the labelling whenever used as ingredients and regardless of the quantities, with some exceptions identified in the same directive. 



The labelling requirements are identified in Regulation 1169/2011 (EUR-Lex - 32011R1169 - EN - EUR-Lex (europa.eu)) entered into force from December 13th 2014, specifying that the presence of each of the 14 regulated allergens must be highlighted separately and emphasised by a different format, and widening the obligation of allergen presence also in unpackaged food products.


Precautionary allergen labelling

The European regulatory framework applies exclusively to food allergens intentionally added as ingredients in the finished product, while the accidental presence of allergens due e.g. to cross-contamination along shared production/transport lines falls outside this obligation.

The occurrence of these so-called "hidden" allergens represents the main risk for the safety of sensitized individuals, under the responsibility of the manufacturing company, which might be requested to withdraw the product from the market. The management of such unintended traces of food allergens is therefore an important part of the food safety management system (HACCP, risk analysis and critical control points); however, the lack of regulatory guidelines on admissible thresholds and official methods of analysis makes the management allergenic risk particularly complex. Despite many efforts carried out by the companies, it is very challenging to manufacture zero-risk products in terms of the unintentional presence of allergens. As a consequence,food manufacturers decide to apply precautionary formulas called PAL (precautionary allergen labelling) as "may contain..." or “prepared in an establishment using...” when they believe that the presence of certain allergens may be out of their control, posing a potential risk for the allergic consumer, thus deferring responsibility for the intake of potentially contaminated food to the consumer.


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