Asthma is poorly controlled if have 4 ng less Vitamin D – April 2019

Cross-sectional associations of vitamin D status with asthma prevalence, exacerbations, and control in New Zealand adults.

J Steroid Biochem Mol Biol. 2019 Apr;188:1-7. doi: 10.1016/j.jsbmb.2018.11.016. Epub 2018 Nov 30.

Win SS1, Camargo CA Jr2, Khaw KT3, Lawes CMM1, Sluyter J1, Waayer D1, Toop L4, Scragg R5.
1 School of Population Health, The University of Auckland, Auckland, New Zealand.
2 Department of Emergency Medicine, and Division of Rheumatology, Allergy, and Immunology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States.
3 Department of Public Health, University of Cambridge, Cambridge, United Kingdom.
4 Department of General Practice, The University of Otago, Christchurch, New Zealand.
5 School of Population Health, The U. of Auckland, Auckland, New Zealand. r.scragg at auckland.ac.nz.

BACKGROUND:
Previous studies, mostly with children, have reported inconsistent findings on the associations of vitamin D status with asthma prevalence, exacerbations, and control. Because of limited research with adults, we examined these associations in a large community-based sample of New Zealand adults.

METHODS:
5110 participants, aged 50-84 years, were recruited from the community into a clinical trial of vitamin D supplementation. The current analysis is based on baseline blood sample collection to measure serum 25-hydroxyvitamin D (25(OH)D), which was deseasonalized for data analyses; and baseline asthma assessment, which included questions on asthma prevalence, urgent medical care for asthma in the previous 12 months, and control of asthma symptoms in the previous 4 weeks.

RESULTS:
702 (13.2%) of 5088 participants reported having doctor-diagnosed asthma. There was no difference in mean (SE) 25(OH)D concentration between participants with and without asthma: 66 (0.9) and 66 (0.4) nmol/L, respectively, adjusting for sex (p = 0.71). However, in multivariable analyses restricted to participants who reported having asthma, mean (SE) 25(OH)D concentration was 6.3 (2.6) nmol/L lower in those who reported having urgent medical care for asthma in the previous 12 months compared to others (p = 0.02), and 10.4 (3.9) nmol/L lower in those with very poor asthma control compared to those who were well-controlled (p = 0.03).

CONCLUSION:
These cross-sectional results suggest that asthmatic adults with lower vitamin D status are more likely to receive urgent asthma medical care and to experience poor asthma control. Clinical trials are needed to determine the role of vitamin D supplementation in asthma management.