5.10.1. Introduction

Adverse reactions to food include immune mediated reactions (food allergy) involving either the synthesis of IgE antibodies or other immunological pathways, and non immune-mediated responses (food intolerance) that are dependent on enzyme deficiencies, pharmacological reactions or, most frequently, on unknown mechanisms.

Figure 5.10.1.             Classification of adverse reactions to food.

(Adapted from EFSA, 2004 and INFOSAN, 2006)

Up to 18% of the European adult population report having experienced health problems by eating a particular food, and about 12% declare to experience such problems almost every time they consume a certain food. This prevalence of self-perceived food hypersensitivity (FHS) is much higher than the prevalence of clinically confirmed food allergy (FA), which has been roughly estimated around 1-3% in adults and 4-6% in children (EFSA, 2004).

Health consequences of FA range from mild symptoms to life-threatening anaphylaxis, mostly affecting the skin, the gastrointestinal and respiratory tracts, the eyes and/or the central nervous system (EFSA, 2004). As for allergies in general, the occurrence of FA is governed by complex interactions between environmental factors (exposure) and personal susceptibility (genetic factors). The type and severity of the clinical manifestations largely depend on the amount of allergen consumed, the time frame in which the food is consumed, the sensitivity of the individual or other modifying factors.

There are more than 80 common food items with allergenic potential (The InformALL database, 2006), although few foods are responsible for the large majority of allergic reactions reported (ILSI, 2003). The ranking of most frequently identified foods causing FA shows a geographical variation and is strongly linked to the age group considered (EFSA, 2004). A partial explanation to the geographical variation in FA lies in the level of exposure to cross-reactive allergens (e.g., cross-reactivity between pollen and certain fruit and vegetables).

The only way of managing FA is avoiding the incriminated food. In the case of IgE-mediated food allergy, where very small amounts of protein (in the range of few micrograms) may trigger a severe allergic reaction, fear of severe reactions in social eating occasions complicate everyday activities and can lead to social isolation and psychological problems that deeply deteriorate one’s quality of life (Mills et al, 2007). On the one hand, adequate labelling of ingredients and clear indication of the potential presence of allergens in foods by cross-contamination in the production line is important to inform susceptible consumers about which foods they should avoid eating. On the other hand, widespread precautionary labelling could inadequately reduce food choice among allergic consumers and even lead to unnecessary, and sometimes harmful, dietary restrictions, particularly in children (Mills et al, 2004).