Garlic: a potential food allergen?

Background: Garlic, is one of the most commonly used spices worldwide but a rare cause of immunoglobulin E (IgE) mediated allergy. Six garlic proteins have been associated with sensitization. Alliin lyase has been classified as the major garlic allergen and demonstrated to be heat labile. Thus, some patients with garlic allergy have reported the ability to ingest cooked garlic without symptoms.

Methods: We report two cases of patients with reaction to garlic, the first to both raw and cooked garlic, and the second to only raw but not cooked garlic. We further examined the proteins found in raw, cooked, and powdered garlic by Sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE), then assessed the patients' sera for IgE to these proteins with immunoblot.

Results: We confirmed that most garlic proteins, to include alliin lyase are degraded with heat and discovered that garlic powder is most consistent with raw garlic on SDS-PAGE. In addition, we corroborated the potential for binding of serum IgE to a rare garlic allergen at ∼70 kDa and demonstrated its heat lability for the first time with immunoblot.

Conclusion: These findings would suggest that patients with garlic allergy could ingest cooked garlic without symptoms but not raw or powdered forms. However, our patient with garlic sensitization reported symptoms with both raw and cooked garlic, which further illustrated the need for further studies.