Anaphylaxis caused by mannitol in pomegranate (Punica granatum)

Immediate hypersensitivity reactions resembling anaphylaxis have been reported in some patients during intravenous infusion of 20% mannitol (1100 mM), an osmotically active agent. An unusual case of anaphylaxis to mannitol arising out of ingestion of pomegranate (Punica granatum) fruit is presented here. Immediate (type I) hypersensitivity to pomegranate was confirmed by skin prick test (SPT) and double-blind placebo-controlled food challenge (DBPCFC). The allergen was identified as mannitol by SPT, following its isolation from pomegranate juice by ion-moderated cation-exchange chromatography. As little as 0.25 ml of pomegranate juice (derived from ∼0.4 g pomegranate fruit), containing mannitol at a concentration of 0.22 mM, caused subjective and objective symptoms of immunoglobulin E (IgE)-medicated allergy in DBPCFC.