Does monosodium glutamate cause flushing (or merely "glutamania")?

Monosodium glutamate is widely regarded as the provocative agent in the "Chinese restaurant syndrome," of which flushing is regarded as part of the reaction. Six subjects were monitored by laser Doppler velocimetry for changes in facial cutaneous blood flow during challenge with monosodium glutamate and its cyclization product, pyroglutamate. Additionally, records of patients challenged with monosodium glutamate in the laboratory were reviewed. No flushing was provoked among the twenty-four people tested, eighteen of whom gave a positive history of Chinese restaurant syndrome flushing. These results indicate that monosodium glutamate-provoked flushing, if it exists at all, must be rare. Monosodium glutamate and its cyclization product, pyroglutamate, may provoke edema and associated symptoms.