I meant to post some time ago about this recent commentary. The authors made some pretty bold statements regarding the importance of fat-soluble vitamins, specifically vitamins D and E. They believe that "at minimum 40% of all asthma in children is because of the deficiency of these vitamins."
The key is for the expectant mother to consume these vitamins during pregnancy. Postnatal supplementation of these vitamins may only show small benefits or no benefits at all in regards to asthma. If the authors are correct, then proper vitamin supplementation during pregnancy can be a cheap, effective way to prevent this childhood condition from ever occurring.