Low vitamin D levels in children with asthma are associated with poorer lung function and the use of larger amounts of steroids, according to an American study reported in the Journal of Allergy and Clinical Immunology.
Researchers at the National Jewish Health medical center in Denver analyzed medical data collected from a group of 100 children with asthma. Overall, 47 percent. of them had insufficient levels of vitamin D, ie the level below 30 nanograms per milliliter (ng / ml) of blood, and 17 percent. had clear deficiencies of this compound – below 20 ng / ml of blood.
They found that asthmatic children with low vitamin D levels had more allergies, worse lung function and used more asthma medications, explains Dr. Daniel Searing, researcher in the study.
The researchers found that children in this group had higher levels of immunoglobulin E (IgE), an indicator of an allergic reaction, and skin tests showed that they were allergic to more allergens. They were also more often allergic to factors present in their homes, such as dog hair or dust mites.
Insufficient vitamin D levels were also associated with poorer results in tests to assess lung function – such as the FEV1 test, which measures the volume of exhaled air during the first second of forced breath.
In addition, these children used more inhaled and oral steroids compared to their peers with normal vitamin D levels. Steroids are considered to be the most effective asthma medications known. Their action is to alleviate the inflammatory processes in the bronchi, which are the basis for the development of the disease.
In further research, scientists found out why vitamin D deficiency in asthmatics has such negative effects. It turned out that this vitamin directly influences the activity of steroids. When its level is too low, the effectiveness of the steroids decreases, which requires increasing their doses in order to obtain the desired therapeutic effect.
Tests on immune cell cultures showed that vitamin D increased the effectiveness of the corticosteroid dexamethasone by a factor of 10. The vitamin also helped overcome cell resistance to this drug.
Our research shows that vitamin D enhances the anti-inflammatory effects of corticosteroids. If future work confirms this finding, patients with asthma will be able to use it to achieve better therapeutic effects with less drug consumption, concludes co-author Dr. Donald Leung. (PAP)