Childhood asthma and vitamin D deficiency in Turkey: is there cause and effect relationship between them?
Italian Journal of Pediatrics 2013, 39:78 doi:10.1186/1824-7288-39-78
Metin Uysalol, Levent Cem Mutlu, Gamze Varol Saracoglu, Erkut Karasu, Savas Guzel, Semra Kayaoglu and Nedret Uzel
Background: Epidemiological studies show that vitamin D deficiency and insufficiency are common worldwide and associated with many diseases including asthma. Our aim was to evaluate vitamin D insufficiency and its clinical consequences.
Methods: This cross-sectional study was carried out on 170 children consisted of 85 who were asthmatic and 85 who were not, aged 2 to 14?years in Tekirdag, Turkey, from September 2009 to May 2010. Children?s basal serum D vitamin levels were determined, and their eating habits, vitamin D intake, exposure to sunlight and use of health services during the previous year were investigated. The severity of asthma and levels of asthma control were assessed according to the Global Initiative for Asthma guidelines.
Results: The difference between mean vitamin D levels in the asthmatic group (mean +/- SD) 16.6 +/- 8.5?ng/mL and the healthy control group (mean +/- SD) 28.2 +/- 19.5?ng/mL was found to be statistically significant (p?<?0.001). Children in the asthma group had less exposure to sunlight and ate a diet less rich in vitamin D (p?<?0.001). A significant difference was observed between the groups regarding the frequency of respiratory tract infections leading to emergency unit admissions and number of hospitalizations (p?<?0.001). It was also shown that a decrease in vitamin D level increased the severity of asthma (p?<?0.001) and decreased the frequency of controlled asthma (p?=?0.010).
Conclusion: This study has demonstrated the correlation between plasma 25 (OH) D levels and childhood asthma. Evidently, this relationship being influenced by multiple factors other than vitamin D, further studies should be conducted to explore the interrelation between all such factors.
- Our study showed that asthmatic children had less exposure to sunlight compared to control group (p < 0.001). This is explained by the fact that families wanted to keep their children at home for fear of an asthma attack if they went outdoors or engaged in physical activities.
- When analysing the RTIs of the previous year, we observed that as vitamin D levels decreased, RTI frequency increased in both the asthmatic and the control groups, and there were frequent incidences of RTI in asthmatic patients with low vitamin D levels , leading to an increase in the severity of the asthma attack .
- Conclusion In summary, in our study, we tried to clarify the role of vitamin D in asthma. We found that vitamin D levels were considerably lower in children with asthma than in healthy children. Exposure to sunlight and a diet rich in vitamin D increased the vitamin D levels in both asthmatic and healthy children. The children with asthma and healthy children with low vitamin D levels had frequent RTIs, leading to more EU admissions and to more use of health services owing to more hospitalizations. A higher frequency of asthma attacks, more severe asthmatic episodes and greater difficulty in asthma control were observed in asthmatic children with low vitamin D levels. We found a relationship between serum vitamin D levels and asthma; however, this relationship could be influenced by multiple factors. Thus, there remains a need to investigate further the relationship between asthma and vitamin D in a multidisciplinary fashion.
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