Schwartzstein 1987.

Methods	Double‐blind, randomised, cross‐over trial
Participants	12 patients (male = 8, female = 4) with chronic stable asthma Mean age 28 years (22 to 44) Mean duration of asthma 16 years (3 to 30)
Interventions	MSG (25 mg/kg) Sodium chloride (equimolar to MSG) Treatments administered in identical capsules
Outcomes	FEV1 and FVC collected at: 0, 15, 30, 45, 60, 75, 90, 105, 120, 150, 180, 210, 240 minutes If FEV1 declined ≥ 10%, FEV1 and FVC were also measured at 270, 300, 330, 360 minutes Symptoms: 24, 48 hours
Notes	Diagnostic criteria: American Thoracic Society This study was supported in part by the International Glutamate Technical Committee
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"The order in which the test substances were given was randomly assigned" Comment: Not described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding (performance bias and detection bias) All outcomes	Low risk	"both subjects and investigators were blinded as to the identity of the medications being given." The drugs were administered in identical capsules
Incomplete outcome data (attrition bias) All outcomes	Low risk	Results of all the subjects were reported
Selective reporting (reporting bias)	Low risk	All the results described in method chapter were reported
Other bias	Unclear risk	"This study was supported in part by the International Glutamate Technical Committee" Comment: we are not certain whether it would influence the result