Vitamin D Deficiency as a Strong Predictor of Asthma in Children

Abstract

Background: Epidemiological studies suggest a link between vitamin D deficiency in early life and development of asthma in later life. Aim: The aim of this study was to measure serum vitamin D levels in asthmatic children and to compare these to healthy non-asthmatic controls. Methods: Asthmatic (n = 483) and healthy control (n = 483) children were recruited from the Pediatric Allergy-Immunology Clinics of Hamad General Hospital and the Primary Health Care Clinics in Qatar from October 2009 to July 2010. All children were below 16 years of age and asthma was diagnosed by a physician. Parents of all children completed extensive questionnaires documenting demographics, child’s feeding practice and vitamin D intake. Serum vitamin D (25-hydroxyvitamin D), calcium, phosphorus, alkaline phosphatase, magnesium, creatinine and parathyroid hormone assays were performed. Subjects with serum containing less than 20 ng/ml vitamin D were deemed deficient. Results: Asthmatic children had significantly reduced serum vitamin D levels compared to non-asthmatic children (p < 0.001); 68.1% of all asthmatics were vitamin D deficient. Asthmatic children had significantly higher degrees of moderate (41.8 vs. 25.1%) and severe (26.3 vs. 11.0%) vitamin D deficiency compared to healthy controls (p < 0.001). Positive familial history of vitamin D deficiency (35.6%, p = 0.005) and asthma (36.4%, p = 0.009) were significantly higher in asthmatic children. Along with vitamin D deficiency, asthmatics also had reduced phosphorus (p < 0.001) and magnesium (p = 0.001) levels but elevated serum alkaline phosphatase (p < 0.001) and IgE (p < 0.001). The majority of asthmatic children had less exposure to sunlight (66.7%, p = 0.006) and less physical activity (71.3%, p < 0.001). Vitamin D deficiency was the strongest predictor of asthma in this population (OR 4.82; 95% CI 2.41–8.63, p < 0.001). Conclusion: The present study revealed that the majority of asthmatic children had vitamin D deficiency compared to control children. Vitamin D deficiency was the major predictor of asthma in Qatari children.

Role of Vitamin D and IgE in bronchial asthma in children in Eastern India

“…The severity of Vitamin D deficiency was found to be associated with severity of childhood asthma. Our finding are also in conformity with other studies which shows that insufficient vitamin D levels are associated with an increase in the risk of asthma exacerbations as found in patients of CAMP cohort and with augmented airway responsiveness and increased risk of asthma hospitalization in children with asthma (15,18) . One study also found an association between serum 25(OH)Vitamin-D levels and risk of an asthma related emergency department visit or hospitalization and concluded that vitamin D deficiency may be the strongest predictor of asthma, stronger than familial history of asthma or serum IgE levels [7] .…”

“…Several epidemiological studies have reported about vitamin D deficiency and its association with an increased incidence of asthma and other allergy symptoms [6]. Some studies have found out vitamin D deficiency was the strongest predictor of asthma stronger than familial history of asthma or serum IgE levels and familial history of vitamin D deficiency also being a predictor of asthma [15] .…”

“…A decrease in lung volumes and capacities with decreased therapeutic response has been suggested in vitamin D deficient asthmatics [3] . The major contributors which lead to vitamin D deficiency are prolonged breastfeeding without vitamin D supplementation, maternal vitamin D deficiency, poor diet and/ or limited sunshine exposure [15] .…”

Effects of Vitamin D Levels on Asthma Control and Severity in Children

“…D vitamininin %10'u gıdalar ile alınmakta %90'ı güneş ışı-ğındaki UV ile deride sentezlenmektedir (3). Günümüzde astım ve D vitamini eksikliği prevalansı oranlarının paralel olarak artmasından batı tipi yaşam tarzının benimsenmesi ile beslenme alışkanlıklarının değişmesi ve dış ortamda daha az vakit geçirilmesinin rol oynadığı düşünülmektedir (4). D vitamini etkisini biyolojik olarak aktif olan formu 1-25(OH)D 3 'ün (kalsitriol) vitamin D reseptörüne (VDR) bağlanması ile göstermektedir.…”

“…Bazı kesitsel çalışmalarda serum D vitamini düzeylerinin astımlı çocuklarda sağlıklı çocuklara göre daha düşük olduğu (4,(10)(11)(12) sınırlı sayıdaki çalışmada serum D vitamini düzeylerindeki yüksekliğinin astım riskinde artmaya neden olduğu gösterilmiştir (13,14). Bazı çalışmalarda ise bu farklılıklar gözlenmemiştir (15)(16)(17)(18)(19).…”