Doctors said prior research on asthma and vitamin C was not conclusive, and in a cross-over study gave 60 children with asthma, aged 7 to 10, 200 mg of vitamin C per day or a placebo for 6-week periods.
At the start and end of the study, researchers measured how much air each child could forcibly exhale, which asthma impairs.
Compared to the start of the study, while there was no change for the placebo group, older children with severe asthma who had been exposed to mold or dampness in their bedroom for more than one year before the study could expel 21 percent more air, and younger children with mild asthma who were not exposed to bedroom mold or dampness could expel 37 percent more air.
Reference: Clinical and Translational Allergy; 2011, Vol. 1, No. 9, Electronic Prepublication