Poor lung function and vitamin D deficiency could be connected

A study published online in the July 12 edition of American Journal of Respiratory and Critical Care Medicine, has linked a deficiency of vitamin D to a worsening lung function in asthmatic children who are treated by the use of corticosteroid inhalers, such as Qvar Beclometasone or Easi-Breathe.

The study came about after researchers made the observation that the prevalence of both asthma and vitamin D deficiency have increased over the last few years. They then set about the task of uncovering any evidence that may suggest a link between these facts.

The 25-hydroxyvitamin D levels were analysed in the serum of 1,024 children aged between 5 and 12 years old from the Childhood Asthma Management Program. Every child involved in the study was suffering from mild to moderate ‘persistent’ asthma and for the evaluations were randomly given either the nonsteroidal anti-inflammatory agent nedocromil, budesonide (an inhaler corticosteroid), or a placebo.

It was determined by researchers that the children’s level of vitamin D would be judged as <20 ng/mL being deficient, 20 to 30 ng/mL being insufficient and >30 ng/mL would be classed as sufficient.

The results showed that 663 children (about 65%), 260 (about 25%), and 101 (about 10%) of the children in the study had vitamin D levels sufficient, insufficient and deficient, respectively. It was determined that those showing a deficient level of vitamin D were more likely to be older and black, or have a higher body mass index in comparison to those children who had ‘sufficient’ or ‘insufficient’ levels of vitamin D.

Ann Chen Wu, from the Harvard Medical School and one of the leading figures in the study, said, “In conclusion, vitamin D sufficiency in patients treated with inhaled corticosteroids is associated with improved lung function in patients with mild to moderate persistent asthma. Monitoring vitamin D levels and/or supplementing with vitamin D could be considered during inhaled corticosteroid treatment for patients with asthma.”

Dr Wu has acknowledged certain constraints with their study though. For example, the sample size of children with a deficient vitamin D level was particularly small. In addition, Dr Wu admits that the children’s vitamin D levels were analysed just once, this being upon entry into the trial.