Here’s a big ol’ list of studies about vitamin D and asthma:
Asthmatic Patients with Vitamin D Deficiency have Decreased Exacerbations after Vitamin Replacement (2017)
Conclusion: 55 asthma patients with vitamin D-deficiency were put on a vitamin D supplementation regimen for one year. They demonstrated a significant reduction in asthma episodes and use of corticosteroid medication. “Asthma exacerbations are favored by vitamin D deficiency and decrease after long-term vitamin D replacement. Patients who are vitamin D deficient benefit from vitamin D supplementation.” This study also found that 93% of asthmatic patients examined were deficient.
Vitamin D Supplementation to Prevent Asthma Exacerbations: A Systematic Review and Meta-Analysis of Individual Participant Data (2017)
Conclusion: This meta-analysis of 8 double-blind, placebo-controlled, randomized control trials testing the effects of vitamin D on asthma severity (955 subjects total) found that vitamin D supplementation significantly reduced the need for and use of corticosteroid medication among those who were initially vitamin D-deficient.
Conclusion: The vitamin D levels of 70 adult asthma patients were measured and compared to 20 matched, healthy controls. The vitamin D levels of the asthma patients were significantly lower than the controls and within the asthma group, those with severe, uncontrolled asthma had much lower levels than the less-severe asthma patients.
Conclusion: This meta-analysis of nine double-blind, randomized, placebo-controlled trials of vitamin D for asthma treatment (1,093 subjects) found that vitamin D supplementation significantly reduced the rate of severe asthma episodes requiring corticosteroid medication and episodes requiring an emergency hospital visit.
Vitamin D Improves Corticosteroids Efficacy and Attenuates Its Side-Effects in an Animal Model of Asthma (2015)
Conclusion: Rat study that found vitamin D supplementation improved the effects of asthma treatment.
Defective IL-10 Expression and In Vitro Steroid-Induced IL-17A in Paediatric Severe Therapy-Resistant Asthma (2014)
Conclusion: Vitamin D aids in the treatment of asthma.
Conclusion: The vitamin D levels of 92 adult asthma patients were measured. Those with higher vitamin D levels were found to suffer fewer asthma episodes, fewer severe asthma episodes, and had fewer emergency room visits over a five-year period.
Conclusion: Vitamin D insufficiency is associated with severe asthma exacerbations in Puerto Rican children, independently of racial ancestry, atopy, or markers of disease severity or control.
High Prevalence of Vitamin D Deficiency Among Inner-City African American Youth with Asthma in Washington, DC (2012)
Conclusion: The vitamin D levels of 85 asthmatic black children were measured and compared to the levels of healthy matched controls. The vitamin D levels of the asthma group were much, much lower than those of the controls.
Vitamin D Supplementation in Children May Prevent Asthma Exacerbation Triggered by Acute Respiratory Infection (2011)
Conclusion: This study found that monthly bolus doses of vitamin D were effective for reducing asthma exacerbations, reducing need for steroid medication, and reducing emergency hospital visits in children with asthma compared to a placebo group.
Serum Vitamin D Levels and Severe Asthma Exacerbations in the Childhood Asthma Management Program Study (2010)
Conclusion: After measuring the vitamin D levels of 1,024 ashmatic children, the researchers concluded that low vitamin D levels are common in those with asthma and are associated with an increased risk of suffering severe asthma episodes. Hospitalizations were more frequent in those with lower vitamin D levels. Children with sufficient vitamin D levels who are not taking corticosteroid medications for their asthma suffer the same rate of severe episodes as children who are taking corticosteroids, but who have lower vitamin D levels. Children who both take corticosteroids and have sufficient vitamin D levels have the lowest rate of severe episodes. This is thought to be due to vitamin D’s positive effect on inflammation and immunomodulation.
Conclusion: The vitamin D levels and pulmonary function of 75 asthmatic children were measured. Less than 10% of the children had sufficient vitamin D levels. Those with higher vitamin D levels demonstrated stronger pulmonary function and reported having less severe, more controllable asthma. *Note: the vitamin D sufficiency standard used in this study is slightly outdated. Using today’s standard, the sufficiency percentage would be a bit lower.
Conclusion: After measuring the vitamin D levels of 616 children with asthma, researchers found that those with lower vitamin D levels suffered from more severe asthma and required more hospitalizations.