Traces of allergens in foods – how much is too much?


Published Online: December 16, 2014

Individuals suffering from food allergies need to practice food avoidance, adopting a lifestyle marked by constant vigilance, with “watching what you eat” becoming a way of life. For this reason, food labels are extremely important for individuals suffering food allergies.

In many parts of the world (including North America and Europe), food labels must list any key allergenic ingredients that are deliberately added to a recipe. In addition, precautionary “may contain” language is often used in labels when there is a risk that allergens may have found their way into otherwise allergen-free food—for example, through the use of common processing lines. However, this precautionary allergen labelling (PAL) is generally unregulated and uses a range of often confusing phrases to convey the potential risks posed by traces of allergenic foods. Identifying “how much is too much” of a trace of an allergen—a question posed in the landmark publication by Taylor, et al —is important for developing evidence-based allergen risk management.

One of the main objectives of the EuroPrevall project was to develop an evidence base that would support quality of life improvements for food-allergic consumers. Coordinated by Professor Clare Mills, this project consists of three interlinked food allergy studies, in which food allergic individuals were diagnosed using the gold standard method of double blind placebo controlled food challenge, and collected data on seven major foods. The data for five of these foods (peanut, hazelnut, celery, fish, and shrimp) were recently reported in The Journal of Allergy and Clinical Immunology.

Using the data gathered from the EuroPrevall study population, dose distributions for these five foods could be modelled. With estimated doses eliciting reactions in 10% of the allergic population four of these foods gave similar dose distributions ranging from around 11mg (1/1000th of a gram) of peanut seed to around 67 mg of hazelnut, 0.1 g of raw celeriac root (celery), and ~0.15g of raw cod fish flesh. Shrimp, however, gave a radically different dose distribution with ~2.8g of raw shrimp flesh causing a reaction in 10% of the shrimp allergic population.

The dose distributions modelled for these five foods contribute to the evidence base developed by the food allergy research community, which is required to identify levels of allergens below which the majority of patients are unlikely to react. These data will inform allergen risk management plans and strategies, such as the Voluntary Incidental Trace Allergen Labelling (VITAL) initiative, and the work being undertaken in the EU-funded project iFAAM (Integrated approaches to food allergen and allergy risk management; http://www.inflammation-repair.manchester.ac.uk/iFAAM/ ), which links together activities led by the Food Allergy Research and Resource Programme in the USA and VITAL. Ultimately such data will support the development of reference doses and action levels for allergens in foods in future, the same way that limits have already been identified for gluten in gluten-free foods. In this way these data will aid food allergy and allergen management, improving safety for food-allergic consumers.

1) Taylor SL et al. Factors affecting the determination of threshold doses for allergenic foods: how much is too much? J Allergy Clin Immunol. 2002 Jan;109(1):24-30.


The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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