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Emerging food allergens 2.1 Allergenic foods – ‘the big eight’ and a few more

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2 Emerging food allergens

2.1 Allergenic foods – ‘the big eight’ and a few more

Any food that contains protein has the potential to cause allergic reactions in some individuals. It is not surprising then that at least 70 different foods have been reported to cause allergic reactions (WHO, 2006), and many more foods have been implicated (Hefle et al., 1996). However, the majority of allergic reactions reported in the medical literature in the past two decades are caused by only a small number of foods (Sampson and Burks, 1996; Hourihane, 1998). These foods are: wheat peanuts, soybeans, milk, eggs, tree nuts, crustacea and fish. Known as the ‘big eight’, these foods account for 90 percent of all food allergies world-wide although regional and country specific differences exist.

While the vast majority of the population can consume these foods safely, very small amounts of these foods can cause serious, and potentially life-threatening, reactions in some individuals. Within the allergic population, individuals vary greatly in their response patterns to any food allergen. An individual’s sensitivity may change with time – for example, some individuals may become less sensitive or even ‘grow out’ of their allergy. Sensitivity may also increase due to an infection or due to uncontrolled asthma.
There is variation among allergenic foods in the amount required to cause an allergic reaction. The variation exists even between closely related foods such as peanut and soy. Allergenic foods may also vary in the severity of reactions they provoke in sensitised individuals. How much of a food is required to cause an allergic reaction and how severe the reaction is, are features that reflect the allergenic potency of the food (Bjőrkstén et al., 2008). Allergenic potency is an important element of the management of the food allergy both at the individual and the population levels.
Cross-reactivity occurs among food proteins, particularly structurally similar or biologically related proteins. The IgE antibodies specific to one protein may bind to a similar protein in a different food. However, clinical reactions due to cross-reactivity are uncommon.

There is currently no cure for food allergy, and allergen avoidance is the only option available to allergic consumers.

While the majority of the population are at no risk of food allergy, food labels provide essential information to allergic consumers to correctly identify food products which contain allergens they need to avoid. Due to the significant risks associated with food allergens, rigorous regulatory measures are warranted. However, the unique nature of food allergy risk, including the risk from accidental exposure to allergens due to unintended presence in food, is a challenge to the food industry and regulators.

2.2 Framework for the assessment of new food allergens

2.2.1 International approach

As discussed above, a number of foods have been recognised as important new food allergens at the country/ region level in addition to the ‘big eight’. These are: sesame in Australia and New Zealand, Canada and the EU; mustard in Canada and the EU; and celery, lupin and molluscs in the EU. These differences reflect population-specific factors such as diet and the reported incidence of allergic reactions in these regulatory jurisdictions. As food consumption patterns in the community change and new foods and ingredients enter the food supply, new allergens are likely to emerge.

Criteria for adding foods to the list of common allergenic foods were previously developed by an ad hoc Panel on Food Allergens for the Codex Alimentarius Commission. The panel recommended that the addition of a food to the list of common allergenic foods should be based on medical evidence that the food causes systemic reactions with typical features of allergic reactions and, where available, prevalence data in children and adults in several countries (WHO, 2000). However, the Codex list of priority allergens remains unchanged.

Canada has recently developed criteria for the addition of new allergens which include the scientific recommendations agreed by the Codex Alimentarius Commission; the allergenic potency of the food or food ingredient (Bjőrkstén et al., 2008), and the potential exposure to the food or food ingredient with specific consideration as to whether the food or food ingredient may become a hidden source of food allergens in pre-packaged food.

Also, the International Life Sciences Institute (ILSI) published a scientific paper proposing a revised set of criteria, including clinical considerations (diagnosis, potency of allergen, severity of reactions), population elements (prevalence, exposure) and modulating factors (food processing) (Björkstén et al., 2008; Løvik, 2009).

The purpose of the mandatory declaration list in the Food Standards Code is to prioritise the regulatory management of food allergens. Therefore, the guiding principle is that inclusion on the list should be determined by the public health significance of the food allergen of concern.

Since allergenicity is not an intrinsic, fully predictable characteristic of a food, premarket assessments such as those commonly used in toxicity assessments, are not applicable. Inevitably, scientific evaluations and any regulatory intervention will lag behind medical observations and reporting of allergic reactions in the community. This is particularly relevant for an emerging allergen where a period of time may lapse before clinical observations are disseminated and diagnostic testing is established. There is currently no systematic data collection on the frequency of allergic reactions to food in Australia and New Zealand.

Recent reports of severe reactions to lupin in Australia highlighted the need for a clear and transparent approach, including data requirements, to identify new allergens of importance in the context of food regulation. The approach is consistent with international criteria and relevant scientific information.

2.2.2 Data requirements to identify new allergens

FSANZ has identified the following data requirements to allow an evaluation of the population health significance of possible new allergens.

  1. Evidence of cause-effect relationship, based upon positive DBPCFC.

  2. Clinical reports of adverse reactions, with typical features of allergic reactions, following exposure to the food or its products.

  3. Data on the prevalence and severity of allergic reactions to the food concerned in the Australian and New Zealand populations.

  4. Information on and extent of use of the food and the range of products in the food supply in Australia and New Zealand.

  5. Data on the allergenic potency of the food.

  6. Where relevant, information on clinical cross reactivity with known allergens.

2.2.3 Sources of information

Data to support the evaluation of the public health significance of a new allergen is to be sourced ideally from the published literature. Where prevalence data are not available, information based on clinical records can be used to support the process of identifying food allergens of concern. In addition, FSANZ may seek direct input from allergy specialists and scientists with relevant expertise, as required.


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