Vitamin D Deficiency Is Associated with Decreased Lung Function in Chinese Adults with Asthma

Harvard University, Cambridge, Massachusetts, United States
Respiration (Impact Factor: 2.59). 12/2010; 81(6):469-75. DOI: 10.1159/000322008
Source: PubMed


Vitamin D deficiency has been associated with markers for allergy and asthma severity in children with asthma. However, its association with Chinese adult asthmatics has not been studied.
To examine whether vitamin D status is associated with lung function and total serum IgE in Chinese adults with newly diagnosed asthma.
We conducted a cross-sectional study including 435 Chinese patients aged >18 years with newly diagnosed asthma. Vitamin D status was assessed by measuring serum 25 hydroxyvitamin D (25OHD) concentrations. The primary outcomes included airflow limitation, as measured by the forced expiratory volume in 1 s (FEV(1)), FEV(1) % predicted, and FEV(1)/forced vital capacity (FVC), and serum total IgE concentration.
Vitamin D deficiency was prevalent in Chinese adults with asthma, with 88.9% of the subjects having 25OHD <50 nmol/l. Serum 25OHD concentration was positively correlated with FEV(1) % predicted (p = 0.02, r = 0.12). After adjusting for age, sex, body mass index, smoking, month of blood collection, and symptom duration, we found significant positive associations between 25OHD concentrations and FEV(1) (in liters), FEV(1) % predicted, and FEV(1)/FVC (p for trend < 0.05 for all). The adjusted odds ratios for the highest versus the lowest 25OHD quartile were 0.50 (0.26-0.96) for FEV(1) <75% predicted and 0.44 (0.20-0.95) for FEV(1)/FVC% <0.75. There was no significant association between 25OHD concentrations and total IgE.
Vitamin D deficiency was highly prevalent in Chinese asthma patients, and vitamin D status was associated with lung function.

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    • "The findings of a cross-sectional study including Chinese patients with newly diagnosed asthma concluded that vitamin D deficiency was highly prevalent and was associated with decreased lung function in this population.101 Also, in asthmatic adult patients, reduced vitamin D levels were associated with impaired lung function, increased airway hyperresponsiveness, and reduced glucocorticoid response, suggesting that supplementation of vitamin D levels in these patients might improve multiple parameters of asthma severity and treatment response.9 "
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    • "This percentage (90%) is higher than that reported in another study of Costa Rican asthmatic children, in which 28% had vitamin D insufficiency,7 and much higher than the 20% reported by Alyasin et al.15 in Iranian children. However, this high percentage is similar to that reported by Li et al.16 in asthmatic adults from China and is consistent with the epidemics of hypovitaminosis D in developing countries reported by Arabi et al.17 "
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    • "In adult patients several clinical studies then analysed vitamin D levels and the severity of allergies such as asthma and chronic rhinoconjunctivitis (CRS). While in one study no difference in serum vitamin D levels of adult asthma patients and healthy controls was observed, Li and coworkers56 found that vitamin D deficiency was highly prevalent in allergy patients and vitamin D status strongly correlated with pulmonary function (FEV1) in asthmatics. Also other observations showed that higher vitamin D serum levels improve pulmonary function in adults while insufficient serum levels are associated with severe pulmonary dysfunction.57 "
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