Internet Symposium on Food Allergens 2(Suppl.6): 1-18 (2000)

Allergen Data Collection - Update:
Codfish(Gadus morhua)
Authors in alphabetical order [contact information]
BESLER (Hamburg, Germany)
ELSAYED (Bergen, Norway)
HELBLING (Bern, Switzerland)


IgE-mediated adverse reactions to fish are a problem frequently encountered in fish processing communities. The codfish inhabits the North, Baltic and White Sea, and the Northern Atlantic and Pacific. It is used as a fresh, salted, dried or more recently as a processed food ingredient of e.g. surimi. Although food processing such as cooking and canning could alter the allergenic potency of codfish allergens, one should be aware of the retained significant allergenicity of these products. Fish and its products always should be declared according to a list of the Codex Alimentarius Commission on mandatory labelling of prepackaged foods.

Fish allergy is common in food allergic children (> 1 year of age) and young adults. Moreover, fish is considered an important food allergen in adults. Although the exact prevalence is unknown, the frequency of allergy to codfish is estimated to be below 0.5% in the general population and about 5-10% in food allergic individuals from different studies. Reactions, usually immediate type, may occur after ingestion, skin contact, or even after inhaling fish vapour. Skin symptoms, such as urticaria or angio-edema, are observed the most, followed by respiratory and gastrointestinal complaints. In severe cases cardiovasculatory symptoms, including anaphylactic shock, may occur.
Codfish amounts as small as a few milligrams can elucidate allergic reactions.
SPT and RAST are reliable tools in the diagnosis of codfish allergy.

More than 15 different allergens have been identified in codfish. The major allergen Gad c 1 (Allergen M) belongs to the Ca2+-binding parvalbumins and was the first food allergen characterized by its IgE-binding epitope structure . Parvalbumins have been identified as cross-reacting IgE-binding allergens in several fish species such as carp, catfish, dogfish, eel, perch, salmon, snapper, and tuna. Despite the high degree of in-vitro cross-reactivity some species may be tolerated by certain allergic individuals. However, all fish species should be avoided until safe ingestion has been proven by challenge tests.

An overview of prevalence data, symptoms, diagnostic and therapeutic features of codfish allergy as well as molecular biological and allergenic properties of codfish allergens is given in tabular form.
  Prevalence of Codfish Allergy
Outgrowing / Persistence of Codfish Allergy
Symptoms of Codfish Allergy
Diagnostic Features of Codfish Allergy
Therapy of Codfish Allergy
Composition of Codfish
Allergens of Codfish
7.1 Sensitization to Codfish Allergens
7.2 Allergen M  (Gad c 1)
7.3 41-kDa-Allergen
Isolation & Preparation
Stability of Codfish Allergens
Allergen Sources
Food Allergen Labelling

The reference lists of the Allergen Data Collections are based mainly on searches on Medline and FSTA (Food Science & Technology Abstracts) databases up to the related dates of publication. The scientific rigor of the studies listed is variable and not subject to critique or evaluation by the authors or the editor of the Allergen Data Collections. The reader should be aware of considerable problems in comparing data from different studies (eg. patient cohorts, diagnostic performances, possible flaws in allergen preparations and methodologies for allergen characterization) and is encouraged to review the original publications.
The information provided by the Internet Symposium on Food Allergens is for educational, communication and information purposes only and is not intended to replace or constitute medical advice or treatments. Neither the authors nor the editorial board of the Internet Symposium on Food Allergens is/are responsible for any use which might be made of the information.

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