Depending on the age of asthmatic children, on their exposure to molds or dampness in their bedroom, and on the severity of their asthma, vitamin C has greater or smaller beneficial effect against asthma, according to a study published in the Clinical and Translational Allergy.
Proposals that vitamin C might be beneficial in the treatment of asthma date back to the 1940s, but the findings from controlled trials have been conflicting.
Drs Mohammed Al-Biltagi from the Tanta University in Egypt and Harri Hemila from the University of Helsinki in Finland analyzed the effect of 0.2 grams per day of vitamin C on 60 asthmatic children aged 7 to 10 years. The effect of vitamin C on the forced expiratory volume per one second (FEV1) was modified by age and exposure to molds or dampness. In the younger children aged 7.0 to 8.2 years with no exposure to molds or dampness, vitamin C administration increased the FEV1 level by 37%. In the older children aged 8.3 to 10 years with exposure to molds or dampness in their bedroom more than one year before the study, vitamin C increased the FEV1 level by only 21%.
The effect of vitamin C on the asthma symptoms was modified by age and the severity of asthma symptoms. In the younger children aged 7.0 to 8.2 years with mild asthma symptoms, the benefit of vitamin C was greatest. In the older children aged 8.3 to 10 years who had severe asthma symptoms, the benefit of vitamin C was smallest.
Drs Al-Biltagi and Hemila conclude that there is strong evidence that the effect of vitamin C on asthmatic children is heterogeneous. They consider that it is important to carry out further research to confirm their findings and to more accurately identify the groups of children who would receive the greatest benefit from vitamin C supplementation.