Ernährung und Allergie
|Allergen Data Collection - Update:
Soybean (Glycine max)
|Authors in alphabetical order [contact
Soybean is the most important nutrient of the legume family. Allergy
to soybeans is common in food allergic children younger than 3 years of
age. Adverse reactions caused by soybean formulas are seen in 14-35% of
cow's milk allergic infants. In food allergic subjects with atopic dermatitis
egg, milk, peanut, and soybean account for almost 90% of allergic reactions.
The prevalence of soybean allergy in the general population is probably
below 0.5%. Symptoms range from skin, gastrointestinal, and respiratory
reactions to severe systemic reactions including anaphylaxis. There are
several reports of inadvertant ingestions of soy protein which caused life-threatening
allergic reactions. Fatal reactions to soybean have also occurred in peanut
allergic individuals, whose sensitivity to soybean was not recognized previously.
Soybean products are used in the manufacture of foods with almost no limits, e.g. as a texturizer, emulsifier, or protein filler. Therefore it is a particularly harzardous hidden allergen in pastries, bakery products, infant foods, sausages, processed meats, and hamburgers. Fermented soybean products such as miso, tempeh, shoyu, and natto are potentially less allergenic than raw soybeans. However, even acid and mold-hydrolyzed soy sauce retain significant allergenic potencies. While soybean lecithins can induce allergic reactions, highly refined soybean oils are generally safe. Soybeans and its products should always be declared according to a list of the Codex Alimentarius Commission on mandatory labelling of prepackaged foods.
About 16 soybean allergens have been identified. Major ingestive allergens are the following water soluble proteins: Gly m Bd 30K (thiol-protease P34), the storage proteins glycinin and beta-conglycinin, and profilin (Gly m 3). Several sequential IgE-binding epitopes have been identified on Gly m Bd 30K, while studies with recombinant profilin fragments indicate the predominant role of conformational epitopes. On the other hand soybean hull proteins Gly m 1 and Gly m 2, and the Kunitz-trypsin inhibitor are involved in respiratory hypersensitivity reactions. Soybean dust has caused several epidemic incidents of asthma in soybean mill workers, harbour workers and animal feed workers as well as in bakers. In asthma, cross-reactivities between soy flour and wheat, rye, and barley flours could be observed. Although there is extensive in vitro cross- reactivity among various legumes, e.g. soybean, peanuts, peas, and beans, clinical reactivity is usually limited to a single legume source.
The present review summarizes data on prevalence, symptoms, diagnostic
features, allergenic potencies of processed foods and transgenic soybeans,
allergen sources, and infant formulas as well as molecular biological and
allergenic properties of the major soybean allergens in tabular form.
The reference lists of the Allergen Data Collections are based mainly on searches of 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 of 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.
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