Review of the regulatory management of food allergens

5 Labelling requirements for the current list of allergens

The current list of allergens in the Code was developed in the late 1990s based on information available at the time. Since then, scientific and clinical research in the area of food allergy has intensified. FSANZ, in consultation with stakeholders, has identified a number of issues relating to the current requirements which could benefit from the research outcomes. These issues are: identifying tree nuts of clinical significance in the context of allergy; evaluating the term ‘fish’ as defined in the code and its usefulness to stakeholders; the distinction between wheat allergy and gluten-related adverse reactions.

5.1 Collective term ‘tree nuts’

Table to clause 4 of Standard 1.2.3 requires the declaration of tree nuts but does not specify the tree nuts known to be significant allergens in Australia and New Zealand. Schedule 4 of Standard 1.4.2, includes a list of sixteen ‘tree nuts’ These are: almonds; beech nuts; Brazil nuts; cashew nuts; chestnuts; coconut³; hazelnuts; hickory nuts; Japanese horse-chestnut; macadamia nuts; pecan; pine nuts; pili nuts; pistachio nuts; sapucaia nut; and walnuts. Standard 1.2.4 – Labelling of ingredients – requires the specific name of the nut must be declared.

FSANZ’s stakeholders, including consumers and food manufacturers have frequently sought clarification on the specific tree nuts that are allergenic and therefore, subject to the mandatory declaration requirements of Standard 1.2.3.

5.1.1 Tree nut allergy

Tree nuts have been reported in the medical literature to cause severe allergic reactions in children and adults. Hill et al. (1997) estimated the prevalence of tree nut allergy in Australian children to be 0.76%. Based on studies by Sicherer et al. (1999; 2003 and 2010), the prevalence of childhood tree nut allergy in the US has increased significantly in the past decade. Data from three telephone surveys conducted over a ten-year period estimates the prevalence as 0.2% in 1997, 0.5% in 2002 and 1.1% in 2008. In Canada, the prevalence of probable allergy to tree nuts was estimated to be 1.14% (Ben-Shoshan et al., 2010).

Tree nuts are among the most frequently implicated food in anaphylaxis (Sampson, 2000). In the United Kingdom, 15 out of the 37 food-induced fatalities recorded from 1992 to 2000, were due to tree nuts (Pumphrey, 2000). A report on fatalities due to anaphylactic reactions to food in the USA identified tree nuts as the cause in 27% of cases (Bock et al., 2001). In Australia, four cases of fatal anaphylaxis due to tree nuts were reported in 1998-1999 in a single adult emergency department in Brisbane, Queensland (Brown and McKinnon, 2001).

Tree nut allergies are commonly reported to almond, Brazil nut, cashew nut, hazelnut, walnut, pecan nut and pistachio nut; and less commonly to macadamia nut, pine nut, coconut and chestnut (Goetz et al., 2005). Regional variations exist with regards to the specific nut most commonly implicated in severe allergic reactions, probably reflecting local consumption patterns as well as other environmental factors such as exposure to pollen allergens. Cashews were most commonly involved in severe non-fatal food allergic reactions reported in the UK and Ireland during 1998–2000 (Macdougall et al., 2001).

In Norway, hazelnut appears to be the most common trigger of allergic reactions to tree nut (Løvik et al., 2004). A retrospective review of 213 peanut or tree nut allergic children in Australia revealed that anaphylaxis to cashew nut was more common than to peanut (Davoren and Peake, 2005). Australian data on childhood allergies to almond, Brazil nut, cashew, hazelnut, and walnut, found the estimated prevalence for cashew nut to be the highest at 0.33% (Hill et al., 1997).

5.1.2 Tree nut allergens

Most of the major allergens identified in tree nuts are seed storage proteins, particularly the 2S albumins and the 7S, 11S and 12S globulins. The 2S albumins are a group of storage proteins present in many dicotyledonous plants. Several major allergens from tree nuts including Brazil nut, walnut, pecan and cashew nuts have been identified as 2S albumins (Pastorello et al., 1998;Tueber et al., 2002; Breiteneder and Radauer, 2004; Robotham et al., 2005; Moreno and Clemente 2008).

The 2S albumins share the conserved disulphide structure common to all members of the prolamin superfamily. However, the IgE-binding sites on these proteins contain hypervariable loop regions that adopt a variety of conformations which may explain the lack of IgE cross-reactivity between the 2S albumins from various plant species (Mills et al., 2004; Barre et al., 2005). Structural homology between the 2S albumin from pecan nut and walnut was observed by Barre et al. (2005) suggests a molecular basis for IgE-binding cross-reactivity between closely related tree nuts.
The 7S and 11S globulins, also known as vicilins and legumins, are the most wide-spread

group of seed storage proteins and are present in mono and dicotyledonous plants including nuts and seeds. Recent studies have confirmed the allergenic nature of the 7S globulin of walnut and cashew nut (Mills et al., 2004); as well as in coconut (Benito et al., 2007). The 11S globulins in almond, cashew and hazelnut have been shown to be allergenic (Beyer et al., 2002; Wang et al., 2003; Mills et al., 2004).

The lipid transfer proteins (LTPs) are polypeptides with a molecular weight of approximately 10 kDa that belong to a family of structurally highly conserved proteins. LTPs are recognised as panallergens in a number of plant species including from hazelnut and walnut (Asero et al., 2000). Environmental factors, such as respiratory sensitisation to pollen from the local flora, may influence the relative significance of certain tree nuts. For example, severe hazelnut allergy is linked to sensitisation to LTP and is common in areas without birch pollen, while the milder form of hazelnut allergy in birch-endemic areas is usually due to cross-reactivity with birch pollen (Pastorello et al., 2002; Flinterman et al., 2008).
Anaphylaxis due to macadamia nut ingestion was first reported in Australia (Sutherland et al., 1999). The patient had a history of infantile eczema and seasonal allergic rhinitis but no history of nut allergy. The authors reported that a 17 kDa protein was serologically cross- reactive with hazelnut. Cases of severe reactions to macadamia nut have been reported recently in Europe, possibly due to the increasing consumption (De Knop et al., 2010).
There have been several reports of allergic and anaphylactic reactions to pine nut but relatively little is published regarding allergenic proteins. IgE-reactive proteins with molecular weights of 17, 50 and 66–68 kDa have been reported (Roux et al., 2003).

Severe and anaphylactic reactions to coconut have been reported (Tueber et al., 1999; Rosado et al., 2002; Roux et al., 2003). However, the literature suggests that reactions to coconut are relatively rare compared with other tree nuts (ASCIA, 2010a). A 7S globulin has been identified as an allergen (Benito et al., 2007).

Chestnut is the third most-prevalent food allergen among both adult and paediatric allergy patients in Korea (Lee, 2004). In Asia, Southern Europe and Turkey, chestnuts have been part of the staple diet and a major source of complex carbohydrate for centuries. Chestnut consumption in Australia and New Zealand is limited and allergic reactions to chestnut have not been reported. Two allergens, Cas s 5 and Cas s 8, from chestnut have been described and cloned. Cas s 5 contains an N-terminal domain with homology to the hevein-like domain, the panallergen associated with latex-fruit syndrome. Cas s 8, is a member of another panallergen family, the LTPs (Roux et al., 2003).

5.1.3 Cross-reactivity among tree nuts

Serologic cross-reactivity among tree nuts was studied by Goetz et al. (2005). Walnut, pecan, and hazelnut form a group of strongly cross-reactive tree nuts. Hazelnut, cashew, Brazil nut, pistachio, and almond form a group of moderately cross-reactive tree nuts. Cross-reactivity between these groups is less pronounced (notably limited cross-reactivity between walnut or pecan nut and Brazil nut). The strongest cross-reactivities among tree nuts appear to follow botanical family groups; i.e. walnut and pecan in the family Juglandaceae; and cashew and pistachio in the family Anacardiaceae.

5.1.4 International regulations

In Europe, the following tree nuts have been identified as important allergens: almonds, hazelnuts, walnuts, cashews, pecan nuts, Brazil nuts, pistachio nuts, macadamia nut and Queensland nuts. Coconuts, chestnuts and pine nuts are not included on the list.
In Canada, the following tree nuts are included in the list of priority food allergens: almonds, Brazil nuts, cashews, hazelnuts, macadamia nuts, pecans, pine nuts, pistachios and walnuts. Coconut and chestnut are not included on the list.

5.1.5 Conclusions

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  A significant volume of literature on tree nut allergy has become available since the mid 1990s, when the Australian and New Zealand allergen regulations were being developed. This information more clearly identifies the specific tree nuts involved in the majority of allergic reactions.
  

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  Tree nuts most commonly implicated in allergic reactions are: almonds, Brazil nut, cashew, hazelnut, macadamia nut, pecan nut, walnut, pistachio nut and pine nut. Coconut and chestnut appear to be less frequently associated with tree nut allergy.
  

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  In line with the European and Canadian approach, a list identifying those tree nuts that are most relevant to food allergy in Australia and New Zealand will improve the clarity of the mandatory requirements.
  

5.1.6 Recommendation

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  FSANZ to consult with the Food Allergy and Intolerance Scientific Advisory Group on the development of a list of the tree nuts that are considered important allergens, and consider options for defining the term tree nuts in the context of allergen declaration.