A group of laboratory based researchers found that adding vitamin D to blood samples from 28 asthma patients lowered the measurable levels of interleukin-17, a key immune system component that is over-active during asthma attacks. Now, the same British scientists who published their findings on vitamin D and interleukin-17 online on May 15, 2013, in the Journal of Allergy and Clinical Immunology are conducting clinical trials to see if vitamin D supplements can actually ease asthma symptoms in patients. The investigators, from Britain’s King's College in London, are focusing on patients whose asthma symptoms don’t respond to steroids and who produce about seven times more interleukin-17 than other asthma patients. Earlier studies have established that high blood levels of “D” are associated with improved asthma control, but the benefits of dietary supplementation with “D” have not been looked at in connection with asthma. The lead researcher, Professor Catherine Hawrylowicz, was quoted by the BBC as saying that the practice of covering up in the sun and using sunscreens may have increased asthma rates. She suggested that treating asthma patients with “D” could help those who are steroid-resistant respond to the medication or enable patients who do respond to steroids to take lower doses.
C.M. Hawrylowicz et al, “Enhanced production of IL-17A in patients with severe asthma is inhibited by 1α,25-dihydroxyvitamin D3 in a glucocorticoid-independent fashion,” The Journal of Allergy and Clinical Immunology, May 15, 2013 doi:pii: S0091-6749(13)00526-5. 10.1016/j.jaci.2013.03.037. [Epub ahead of print]