Glutamate-Induced Asthmatic Reactions

Abstract

Ingested chemicals are becoming increasingly recognized as provokers of acute severe asthma. Aspirin, tartrazine and the common preservative, metabisulfite, have been recognized for some years. Provocation of asthma by monosodium L-glutamate (MSG), a widely used flavour enhancer, was first reported by our group in 1981. This report describes challenge studies with MSG in 32 asthmatic patients, a number of whom had experienced severe asthma following Chinese restaurant meals. The patients received an additive-free diet for 5 days prior to challenge and were challenged in hospital after an overnight fast, with capsules of MSG. They were challenged in a single-blind, placebo-controlled fashion with increasing doses of MSG from 0.5 g to 5 g. Twelve patients reacted and they fell into two groups. Group 1 consisted of 6 patients who developed asthma and symptoms of the Chinese Restaurant Syndrome 1–2 hours after ingestion of MSG. Group 2 patients did not develop symptoms of Chinese Restaurant Syndrome and their asthma was delayed 6–12 hours after ingestion of MSG. These challenge studies confirm that MSG can provoke asthma. The reaction to MSG is dose dependent and may be delayed up to 12 hours, making recognition difficult for both patient and physician.