Study design. In the antioxidant study, asthmatic children were recruited from 1998 to 2000 and followed during 12 weeks with spirometric tests during the follow-up. At baseline, children were randomly assigned to either a placebo or a supplementation group (vitamin C 250 mg/day and vitamin E 50 mg/day). In the EVA study, asthmatic children were recruited and followed during 16 weeks from 2003 to 2004. Every two weeks children had a spirometric test. In both studies, children provided blood sample at baseline.