5.10.2. Data sources
5.10.2.1.
Allergen databases
Data on allergens in general, and on food allergens in
particular, are scattered among a large number of allergen databases that have
been created for a variety of purposes (Table 1). These include molecular
databases focused on protein sequences and structures, informational databases
focused on clinical, biochemical and epidemiological data related to protein
allergens, a database on allergen nomenclature, and other informational
websites that are peripherally-related to research on allergens (Brusic et al,
2003; Gendel et al, 2006). The design, structure, search/ability and
information contained on the above databases vary greatly, with a high level of
redundancy and relatively low coverage of allergens by individual databases.
(Brusic et al, 2003).
Table 5.10.1. Available allergen
databases.
The PROTALL project (FAIR-CT98-4356) established a
European network of over 30 clinicians, food scientists and plant biologists
with expertise relevant to studying the problems of food allergy, with funding
from the European Union (EU) until December 2001. The network examined the
relationship between the allergenic potential of plant food proteins, their
molecular structures and biological activities, and established a database with
biochemical and clinical information on 77 allergens from 48 plant species
involved in classical IgE-mediated allergic reactions (
http://www.ifr.ac.uk/protall/).
More recently, the INFORMALL database has been developed
with funding from the European Commission (Communicating about Food Allergies –
Information for Consumers, Regulators and Industry - Informall,
QLRT-2001-02284) to provide a credible source of information on allergenic food
materials of both plant and animal origin. This search/able database includes
the common name, scientific name, occurrence, allergy information
(cross-reactivity, clinical manifestations, diagnosis), other information (e.g.
EU legislation) and taxonomic information for more than 80 food allergens.
5.10.2.2 Most
common allergenic foods in Europe
As follow-up of discussions in Codex Alimentarius and
consultations between the Commission and Member States of the EU on the
question of labelling food ingredients to which some individuals may exhibit
adverse reactions, the Scientific Committee for Food (SCF) was asked to
identify the foods, food components and food ingredients more frequently
associated with adverse reactions in European consumers. The major sensitising
foods identified were cow’s milk, fruits, legumes (especially peanuts and
soybean), eggs, crustaceae (shrimps, crab, lobster and crayfish), tree nuts
(almonds, walnuts, hazelnuts, Brazil nuts etc.), fish, vegetables (celery and
other foods of the Ombelliferae family), wheat and other cereals (SCF, 1995).
5.10.2.3.
Prevalence of food hypersensitivity and food allergy
The first attempt to collect data on prevalence rates of
self-perceived FHS using standardized questions to allow between-country
comparisons across Europe has been made in the context of the European
Community Respiratory Health Survey (ECRHS, http://www.ecrhs.org/), a multicenter research study
funded by the European Commission (EC) aimed to compare the prevalence of adult
asthma between countries (mostly European), using standardized epidemiological
methods and to identify the risk factors associated with the international
variation in asthma prevalence throughout Europe.
Data of similar quality and consistency are lacking,
however, for FA. At present, available data on FA prevalence come from
individual studies conducted in single Member States by using different
methodologies that preclude cross-comparisons, and usually refer to hospital
populations of sensitive individuals among whom FA are more common than in the
general population. Notably, little information on sex and gender differences
has been collected, although the impact of these factors on both self-perceived
and clinically diagnosed FA may be substantial and age-dependant (DunnGalvin A,
2006). In addition, most of the available studies have used as diagnostic
criteria for FA questionnaires on self-reported FA (which usually do not
differentiate between FA and food intolerance) and/or sensitization tests
(e.g., skin prick tests, specific IgE tests) rather than gold standard
methodology (i.e food challenge studies and particularly double blind placebo
controlled), which can be implemented only under strict conditions and are
often avoided in highly sensitised subjects. Questionnaires and sensitization
tests tend to overestimate the prevalence of clinically relevant IgE-mediated
FA and to underestimate the prevalence of FA non IgE-mediated (Woods et al,
2002; EFSA, 2004). Finally, allergic reactions to foods are often
inconsistently classified and reported by the medical community, and are not
always adequately recognised and treated. Indeed, there are serious
discrepancies in the way the International Classification of Diseases (ICD)
coding is used to characterise and classify food allergic reactions across Europe (WHO, 1975 and 1993). It should also be noted that in ICD-9, there is no specific
reference to food allergy, apart from dermatitis due to ingested food (Table
2).
Table 5.10.2. ICD codes presumed to have been used for the
classification of allergic reactions to food in 11 countries of the European
Union
Source: EU SCOOP Report of experts participating in Task 7.2, 1998
Taking into account the above, the EC has funded
EuroPrevall (http://www.europrevall.org/), a pan-European
project including 56 partners from 21 countries (19 European) with the
objective of characterising the patterns and prevalence of IgE-mediated FA across
Europe in infants, children and adults including, but not restricted to, foods
for which labelling is mandatory under Community legislation (see section 5).
EuroPrevall is still ongoing and no prevalence data have been published yet.
However, a meta-analysis of published data has been performed in the context of
this project to assess the prevalence of IgE-mediated FA to the foods that are
responsible for the majority of FA episodes (peanut, milk, egg, fish and
shellfish), taking into account the age group and the method used for diagnosis
of FA (Rona et al, 2007). For the purpose of this report, additional, data for
other common allergenic foods will be extracted from the Opinion of the
Scientific Panel on Dietetic Products, Nutrition and Allergies on a request
from the Commission relating to the evaluation of allergenic foods for
labelling purposes (EFSA, 2004), which is the most updated review of available
data on FA prevalence across Europe for those foods.
