Nasal response to carrot and lettuce challenge in allergic patients

Food allergies are usually recognized by historical triggers; yet, on occasion, objective testing may be needed to demonstrate allergic causes more convincingly.

Two atopic adult patients presented with respiratory and/or ocular symptoms with an unusual association to handling or eating of vegetables. A third atopic patient presented without attribution of symptoms to vegetable exposure. In all, work-up had revealed positive skin tests and in vitro assays for specific IgE to carrot and/or lettuce; none had gastrointestinal complaints.

To assess further these unusual histories and/or IgE antibody findings, laboratory challenge was performed with nasal resistance being used as a monitor of rhinitic reaction.

The first two patients had prolonged nasal objective responses to challenge; the third had a transient response to one of two challenges.

We conclude that lettuce and carrot can account for clinically significant IgE-mediated allergic reactions, manifested by nasal obstruction. This laboratory reaction to foodstuffs appears to correlate with patient-reported upper airway and ocular symptoms.