There is growing evidence that suggests a relationship between vitamin D and asthma. Based on results from epidemiologic and animal studies, vitamin D may play a role in the pathogenesis of asthma via its effects on the innate and adaptive immune system. [1–7] Among children with asthma, several cross-sectional studies have reported associations between low blood concentrations of vitamin D and increased severity of disease. [8–12]
Formal guidelines on the vitamin D requirements for the healthy population have largely focused on evidence for skeletal manifestations of vitamin D deficiency. [13] There is uncertainty as to whether vitamin D supplementation during childhood may improve asthma outcomes. Given the ongoing research and emerging evidence on this topic, it is important to synthesize the evidence for this intervention to support decision-making for patients and for health care providers.