Airway effects of monosodium glutamate in subjects with chronic stable asthma

We studied the effect of oral monosodium glutamate (MSG) on airways function in 12 subjects with a history of chronic stable asthma in a double-blind, randomized, crossover protocol. Subjects ingested either 25 mg/kg of MSG or sodium chloride (equimolar to MSG) following a 6-hour fast. Spirometry [forced expiratory volume in 1 second (FEV1) and forced vital capacity] was performed before administration of the test substances and for a minimum of 4 hours thereafter. At no time during the observation period was the mean change in FEV1 more negative following MGS than following placebo. MSG is unlikely to be a contributing factor in bouts of bronchospasm in subjects with asthma, and routine avoidance of MSG by individuals with asthma need not be advised.