Roasted hazelnuts--allergenic activity evaluated by double-blind, placebo-controlled food challenge.
BACKGROUND
Allergy to hazelnuts is a common example of birch pollen related food allergy. Symptoms upon ingestion are often confined to the mouth and throat, but severe systemic reactions have been described in some patients. The aim of the study was to evaluate the reduction in allergenicity by roasting of the nuts.


METHODS
Double-blind, placebo-controlled food challenges (DBPCFC) with roasted hazelnuts (140 degrees C, 40 min) were performed in 17 birch pollen allergic patients with DBPCFC-confirmed food allergy to raw hazelnuts. The effect of roasting was further evaluated by skin prick test (SPT), histamine release (HR), measurement of specific IgE, and IgE-inhibition experiments.


RESULTS
In 5/17 patients the DBPCFC with the roasted nuts were positive. The symptoms were generally mild and included OAS (oral allergy syndrome) in all patients. Roasting of the nuts significantly reduced the allergenic activity evaluated by SPT, HR, specific IgE, and IgE-inhibition. Immunoblotting experiments with recombinant hazelnut allergens showed sensitization against Cor a 1.04 in 16/17 patients and against Cor a 2 in 7/17 patients. None of the patients were sensitized to Cor a 8. Challenge-positive patients did not differ from the rest in IgE-binding pattern.


CONCLUSIONS
All the applied methods indicated that roasting of hazelnuts reduces the allergenicity, but since 5/17 birch pollen allergic patients were DBPCFC-positive to the roasted nuts, ingestion of roasted hazelnuts or products containing roasted hazelnuts can not be considered safe for a number of hazelnut allergic consumers. For patients with a history of severe allergic symptoms upon ingestion of hazelnuts, thorough and conscientious food labelling of hazelnuts and hazelnut residues is essential.
Hansen
K Skamstrup
KS
Allergy Clinic, Department 7551, National University Hospital, Blegdamsvej 9, DK-2100 Copenhagen, Denmark.
Ballmer-Weber
B K
BK
Lüttkopf
D
D
Skov
P S
PS
Wüthrich
B
B
Bindslev-Jensen
C
C
Vieths
S
S
Poulsen
L K
LK
D000293:Adolescent; D000328:Adult; D000368:Aged; D000485:Allergens / Q000008:administration & dosage / Q000009:adverse effects*; D000918:Antibody Specificity / Q000276:immunology; D018849:Controlled Clinical Trials as Topic; D003296:Cooking / Q000379:methods; D031211:Corylus / Q000009:adverse effects*; D003718:Denmark; D004306:Dose-Response Relationship, Immunologic; D004311:Double-Blind Method; D005260:Female; D006636:Histamine Release / Q000276:immunology; D006801:Humans; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000276:immunology; D008297:Male; D008875:Middle Aged; D021184:Nut Hypersensitivity / Q000209:etiology*; D011058:Pollen / Q000009:adverse effects; D012720:Severity of Illness Index; D012882:Skin Tests; D013557:Switzerland; D013577:Syndrome
D000485:Allergens; D007073:Immunoglobulin E