Hidden allergens. What should be there but is not always on the label?

Food allergy is a growing health problem that affects people worldwide, especially in developed countries [1,2]. According to epidemiological evidence, this type of allergy occurs in 6-8% of children and 2-4% in adults [2]. In controlling food allergy, identifying and then avoiding the allergen plays a crucial role. However, even despite careful reading of food labels and elimination of specific products from the diet, the risk of an allergic reaction still exists [3,4]. This is due to so-called hidden allergens in particular.

Hidden allergens can be responsible for, for instance, severe anaphylactic reactions [3]. Contact with them is most often accidental and unpredictable. While some directly contaminate a product, others are found in the product as a result of cross-contamination [4].

Cross-contamination is the unintentional transfer of allergens from one product to another. This occurs, for example, in establishments that simultaneously produce food containing allergens (e.g. cow’s milk proteins) and food free of such ingredients [8]. Cross-contamination also occurs in other places, such as ice cream parlours – by putting different servings (flavours) of ice cream with the same spoon [1]. The use of latex gloves by people in contact with food is a potential route of latex allergen transmission [4]. On the other hand, house dust mites can be transmitted in flour, which then ends up in pizza or pasta [4].

In addition, there are many rare allergens that are not – because they do not need to be – labelled as allergenic substances on product packaging [4].

This leads to a situation where idiopathic anaphylaxis, i.e. caused by unidentified allergens, is found in a high proportion of hospitalised patients [4]. Spanish researchers in 2007 looked at 530 allergic reactions to foods. They found that 22.4%, or almost a quarter of them, were caused by undetermined allergens [5]. This phenomenon is therefore a serious threat with many social and legal consequences [1]. A great responsibility lies not only on food manufacturers, but also on restaurateurs, hoteliers, and caterers [1].

Allergens can be present in any product, so no food is 100% safe for consumers [1]. Particularly problematic are the already mentioned rare allergens, of which food additives are a significant group.

Dyes and preservatives

Food additives – i.e. substances used to maintain or improve the safety, freshness, taste, texture, appearance of products – are very rare irritants. Reactions to such substances are observed in less than 1% of adults and 2% of children, but these can be severe reactions [4]. An expert report carried out by NIK showed that food colourings, especially synthetic ones (e.g. E122, E123, E110), as well as preservatives from the sulphite group are allergenic [6]. Some of them (e.g. E120 – cochineal, E124 – cochineal red, E 129 – Allura red, E223 – sodium pyrosulphite ) have been indicated as a cause of anaphylactic reactions [6,11].

These additives, found in many shop products (e.g. beverages, cured meats), are dangerous especially for children and people allergic to salicylates [6]. Cochineal increases atopic eczema in paediatric patients [4]. Among others, the commonly used sodium benzoate (E211) has been identified as a causer of other adverse skin reactions [4].

Thickeners

Hidden allergens also include thickening agents, e.g. pectin, which can sensitise especially people sensitive to cashew nuts and pistachios. The co-occurrence of allergy to pectin and the indicated nuts has been proven, although the basis of this phenomenon has not been clarified [4]. Pectins are found, for instance, in jelly beans, which have been repeatedly described in the context of food allergies in children [1,4]. Another thickening agent, carboxymethylcellulose, has contributed to several cases of anaphylaxis [4].

Aromas and spices

Further hidden allergens are spices and aromas, which are found not only in food available on shop shelves, but also in home products [4]. It is believed that allergy to spices is often secondary to inhalant allergy [4,12]. Cross-reactivity between spice allergens and pollen (e.g. mugwort, birch, celery) occurs [12]. Allergic spices from the celery family include coriander, cumin, aniseed and fennel [12]. Cases of anaphylactic reactions to pepper and fenugreek and angioedema after ingestion of oregano and sage have also been reported in the literature [4]. Importantly, fenugreek shows significant cross-reactivity with peanut proteins [4].

Sensitising aromas and flavourings include vanilla extract [13] and limonene [14].

The allergen content of food is difficult to detect and accurately determine [1]. Meanwhile, even low concentrations of allergenic substances in particularly sensitive individuals can trigger an anaphylactic reaction [1]. This poses a major problem for researchers trying to establish safe levels of major allergens in foods [1].

According to current law, it is necessary to label the following 14 allergenic or intolerance-inducing substances:

1. Cereals containing gluten (e.g. wheat, barley, rye, oats) and products thereof.
2. Crustaceans (e.g. prawns, crabs, crawfish, lobster) and products thereof.
3. Eggs and products thereof
4. Fish and products thereof
5. Peanuts (groundnuts) and products thereof.
6. Soya and products thereof.
7. Milk and products thereof (including lactose).
8. Nuts (e.g. walnuts, hazelnuts, almonds, pistachios) and products thereof.
9. Celery and products thereof.
10. Mustard and products thereof.
11. Sesame seeds and products thereof.
12. Sulphur dioxide and sulphites at concentrations of more than 10 mg/kg or 10 mg/l.
13. Lupin and products thereof.
14. Molluscs (e.g. mussels, snails, clams, oysters, mussels, squid) and products thereof.

Labels must indicate the specific type of allergenic ingredient. Its name should be highlighted (e.g. in a different colour, font, background). For products sold loose (unpackaged), allergen information should be found on labels [7].

Scientists have long stressed that the current ‘list of 14 allergens’ (according to the European Food Safety Authority – EFSA) needs to be expanded [10]. Reports continue to emerge highlighting further allergenic products and substances, such as peas, lentils, buckwheat, goat’s and sheep’s milk, kiwi or α-galactose (present in meat) [10]. These can cause severe allergic reactions, including cross-reactions [10]. It is therefore to be expected – and hoped – that changes in allergen labelling will take place in the near future.

Aleksandra Lipiec 

__________________

translation: Julia Majsiak