Vitamin D no help in asthma

In a randomised clinical trial, investigators from nine academic medical centres in the United States recruited 408 symptomatic adult asthma patients with vitamin D deficiency, diagnosed as 25-hydroxyvitamin-D levels of less than 30ng/ml (75nmol/L). The average level was 18ng/ml (45nmol/L).

All patients received the same dose of inhaled corticosteroid; however, half the patients were also given an oral vitamin D supplement, while the other half received a placebo. 

If asthma control was achieved after 12 weeks, the corticosteroid dose was halved for the following eight