Vitamin D insufficiency is associated with adverse outcomes in in asthma and many other diseases. What is not clear however is whether this association is causative or not. It is not known if supplementing inhaled corticosteroids with oral vitamin D3 improves outcomes in patients with asthma and vitamin D insufficiency.
This large randomized, double-blind, parallel, placebo-controlled trial evaluated if vitamin D supplementation improved the efficacy of inhaled corticosteroids in 408 adults with symptomatic asthma and lower vitamin D levels, less than 30 ng/mL (VIDA - Vitamin D Add-on Therapy Enhances Corticosteroid Responsiveness in Asthma).
Oral vitamin D3 (100 000 IU once, then 4000 IU/d for 28 weeks) or placebo was added to inhaled ciclesonide (320 µg/d). In the vitamin D3 treatment group, 82% of participants achieved a serum 25-hydroxyvitamin D level of 30 ng/mL or greater (mean 42 ng/mL).
Treatment with vitamin D3 did not alter the rate of first treatment failure during 28 weeks.
Vitamin D3 did not reduce the rate of first treatment failure or exacerbation in adults with persistent asthma and vitamin D insufficiency. These findings do not support a strategy of therapeutic vitamin D3 supplementation in patients with symptomatic asthma.
Despite the study findings, the lead investigator Dr. Castro's "gut feeling" is that vitamin D supplementation will prove to be useful in at least some people with asthma who have low vitamin D. That's nice but the guideline recommendations are based on scientific evidence rather than feelings. The current evidence does not support vitamin D therapy in asthma.
Severe asthma (click to enlarge the image).
Effect of Vitamin D3 on Asthma Treatment Failures in Adults With Symptomatic Asthma and Lower Vitamin D Levels. The VIDA Randomized Clinical Trial. Mario Castro et al.
JAMA. Published online May 18, 2014. doi:10.1001/jama.2014.5052
Video: Author Video Interview: Effect of Vitamin D3 on Asthma Treatment Failures in Adults With Symptomatic Asthma and Lower Vitamin D Levels (5:05)
The first randomized controlled trial to investigate whether taking vitamin D can improve asthma: answer is no http://buff.ly/1knrgDx
Vitamin D Gets Mixed Results in Prospective Asthma Trial - Medscape http://buff.ly/1kntORO
Related: Vitamin D3 Supplementation Did Not Decrease Upper Respiratory Tract Infections in Healthy Adults. JAMA. 2012;308(13):1333-1339. doi:10.1001/jama.2012.12505.