THE EFFECTS OF MONOSODIUM GLUTAMATE IN ADULTS WITH ASTHMA WHO PERCEIVE THEMSELVES TO BE MONOSODIUM GLUTAMATE-INTOLERANT

Background: Many previous clinical studies of food-induced asthma suff er from inadequate baseline or control data. A statistically valid, ra ndomized, double-blind, placebo-controlled, monosodium glutamate (MSG) -challenge protocol was developed for identifying early and late asthm atic reactions in an individual.Objective: We sought to determine whet her MSG would induce bronchoconstriction in a group of adults with ast hma who perceived that they were MSG sensitive. Methods: Twelve subjec ts (seven women, mean age 35.3 years) with clinically documented asthm a and a perception of MSG-induced asthma were recruited. FEV1 and peak expiratory flow data were obtained for 3 whole control days, as well as time-matched data for 3 separate challenge days (1 gm MSG, 5 gm MSG , and 5 gm lactose [placebo]). Opaque capsule challenges were given as a single dose in the morning after an overnight fast. Subjects compli ed with atl elimination diet throughout the study. Nonspecific bronchi al hyperresponsiveness was measured at baseline, after the control day s, and at the conclusion of the challenges. Venous blood samples were taken at baseline and on each challenge day to determine soluble infla mmatory marker (eosinophil cationic protein and tryptase) activity. Re sults: No immediate or definite late asthmatic reactions occurred. One subject's FEV1 declined more than 15% on MSG challenge, but 95% confi dence limits for the control-day spirometry showed that this decline w as within her daily variation, hence the challenge was deemed to be ne gative. No significant changes in bronchial hyperresponsiveness or sol uble inflammatory markers were found. Conclusions: MSG induced asthma was not demonstrated in this study. This study highlighted the importa nce of adequate baseline and control data and indicated that such a ri gorous protocol for individual assessment is feasible.