Allergic hypersensitivity to garlic and onion in children and adults.

Background: China and Spain are world leaders in the consumption of edible bulbs (garlic and onion), but there are few references to their capacity to cause allergic symptoms. The target was to study allergic sensitization and clinical symptoms associated with garlic and onion consumption in a large sample of allergic patients.

Methods: An observational cross-sectional study was conducted, testing garlic and onion extracts in 8109 patients of all ages seen by our allergy clinic in 2018. Forty-four aeroallergens and foods were tested, including garlic and onion, with prick test and determination of specific IgE. Oral provocation and contact tests were performed if a delayed reaction was suspected. Western Blot was performed in the serum of patients positive to garlic and onion.

Results: We conducted 356,798 skin tests and 4254 specific IgE determinations. Of the 8109 patients tested, 2508 (30.92%) presented with symptoms associated with food intake and, in these patients, food hypersensitivity was detected by skin test, positive specific IgE or provocation in 924 patients, and was caused by garlic or onions in 27, indicating a prevalence of 2.92%. Immunodetection showed an association between the symptoms and a specific LTP to these bulbs, without cross-reactivity with other LTPs in the Mediterranean diet (peach, wheat).

Conclusions: Allergic hypersensitivity to garlic and onions should not be underestimated and, given their high consumption, should be included in the diagnostic food allergy battery.