Low levels may also hinder response to steroid treatment, study finds
THURSDAY, Jan. 28 (HealthDay News) -- People with asthma who have low levels of vitamin D fare worse than those with high levels of the "sunshine" vitamin, a new study finds.
Researchers found that asthmatics with high vitamin D levels have better lung function and respond better to treatment than asthmatics with low vitamin D levels do.
"Our findings suggest that low vitamin D levels are associated with worse asthma," said lead researcher Dr. E. Rand Sutherland, from the division of pulmonary and critical care medicine at National Jewish Health in Denver.
In addition, vitamin D levels predict how well "somebody is going to respond to steroidal asthma medications," he said. "It may be that vitamin D is acting as a modifier of the immune system or a modifier of steroid response in ways that are relevant to people with asthma."
The report is published in the Jan. 28 online edition of the American Journal of Respiratory and Critical Care Medicine.
For the study, Sutherland's team took the vitamin D levels of 54 asthmatics and assessed lung function, airway hyper-responsiveness, which is the prevalence of airway constriction, and response to steroid treatment.
People with low levels of vitamin D in their blood did worse on the tests that evaluated lung function and airway hyper-responsiveness, the researchers found.
In those with vitamin levels below 30 nanograms per milliliter (ng/ml), airway hyper-responsiveness almost doubled, compared to those with more D in their blood.
Low vitamin D levels were also associated with a worse response to steroid therapy and increased production of the pro-inflammatory cytokine, TNF-alpha. This raises the possibility that low vitamin D levels are tied to increased inflammation of the airways.
The heaviest participants had the lowest levels of vita
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