Insufficient vitamin D may boost asthma risk

Children with insufficient vitamin D levels may be at higher risk of developing asthma, suggests a new study. Vitamin D levels were also associated with increased frequency of hospitalization, according to a study with 616 Costa Rican children with asthma. The researchers who were led by Dr. John Brehm from Brigham and Women's Hospital and Harvard Medical School concluded: “In these children, lower vitamin D levels are associated with increased markers of allergy and asthma severity.” 

Dr. Brehm and his co-workers sought to build on previous evidence that low maternal vitamin D intake during pregnancy may adversely affect the respiratory health of their children and increase the prevalence of asthma symptoms in early childhood. Vitamin D levels, calculated using serum concentrations of 25- hydroxyvitamin D (25(OH)D), the non-active “storage” form of the vitamin in the body, were measured in 616 asthmatic children in Costa Rica aged between 6 and 14.

Vitamin D insufficiency, quantified as 25(OH)D levels below 30 ng/ml (or 75 nmol/L), was documented in 175 children. Vitamin D deficiency is when 25(OH)D levels are below 15 ng/ml (37.5 nmol/L). 25(OH)D levels were inversely associated with levels of immunoglobulin E (IgE), the predominant antibody associated with an allergic response, said the researchers. Furthermore, “a log10 unit increase in vitamin D levels was associated with reduced odds of any hospitalization in the previous year, any use of anti-inflammatory medications in the previous year, and increased airway responsiveness,” wrote the researchers. The study is published ahead of print on January 29, 2009 issue of the American Journal of Respiratory and Critical Care Medicine.