Vitamin D and Asthma

Low levels of vitamin D may be linked to greater asthma severity.
The Los Angeles Times (1/28, Roan) "Booster Shots" blog reported that researchers at the National Jewish Health in Denver found that "adult asthma patients with the highest levels of vitamin D in their blood had better lung function compared with people with the lowest levels" in a study appearing in the American Journal of Respiratory and Critical Care Medicine.
"For every 1-ng/mL increase in serum levels of 25-hydroxyvitamin D (25-OH-D), forced one-second expiratory volume (FEV1) increased by 21 mL," MedPage Today (1/28, Gever) reported. The 54-patient study "also showed that airway hyperreactivity in those with serum 25-OH-D levels below 30 ng/mL -- defined as vitamin D insufficiency -- measured at almost twice the average levels seen in those with normal levels of 25-OH-D."
"Low vitamin D levels were also associated with a worse response to steroid therapy and increased production of the pro-inflammatory cytokine, TNF-alpha," HealthDay (1/28, Reinberg) reported. "This raises the possibility that low vitamin D levels are tied to increased inflammation of the airways." Nothing that the "heaviest participants had the lowest levels of vitamin D," the authors say that the "(lack of vitamin D) may be a factor linking" obesity and asthma.
WebMD (1/28, Warner) quotes lead investigator E. Rand Sutherland, MD, MPH, as saying, "The next question to answer is whether giving supplemental vitamin D will lead to clinical improvements in patients with asthma."