ABSTRACT
Asthma is a heterogeneous disease with multiple phenotypes. Epidemiologic studies suggest a close relationship between vitamin E and the occurrence of asthma, wheezing and atopic conditions during childhood. Previous results on its effects have been conflicting. The aim of this meta-analysis was to critically examine the current evidence on the association of vitamin E with childhood asthma and wheezing. We searched electronic databases for observational studies in English-language journals published from 2000 to 2016. The initial search found 420 titles; nineteen studies were eligible according to the abstracts and details, which included reporting asthma or wheeze as an outcome. None of the articles included in this meta-analysis reported side effects of vitamin E supplementation during pregnancy. This meta-analysis found that vitamin E supplementation during pregnancy influenced the risk of asthma. To better understand the effectiveness and safety of vitamin E in children with asthma, large-scale, well-designed and randomized controlled trials are needed.