Low vitamin D levels may be detrimental to respiratory health
Decreased serum vitamin D levels appear to confer an increased risk of asthma, bronchitis, wheeze and chest tightness, a study reports. Conversely, increased vitamin D levels are associated with higher levels of lung function.
Researchers examined 5,011 adults (mean age 58 years; 45 percent male), analysing data on serum 25-hydroxyvitamin D (25OHD) and history of respiratory disease. All participants underwent spirometry and completed a questionnaire detailing respiratory symptoms.
Analysis was performed using logistic and linear regression models with adjustments for age, sex, season and smoking (model A), plus body mass index and physical activity level (model B), plus history of chronic diseases (model C).
Of the patients, 10 percent were current smokers and 12 percent were taking vitamin D supplements. The prevalence rate of vitamin D deficiency (25OHD level <50 nmol/L) was 8.0 percent.
All three models showed that participants with 25OHD <50 nmol/L had higher odds of having asthma (model C: odds ratio [OR], 1.32; 95 percent CI, 1.00–1.73), bronchitis (OR, 1.54; 1.17–2.01), wheeze (OR, 1.37; 1.10–1.71) and chest tightness (OR, 1.42; 1.10–1.83).
On the other hand, participants with vitamin D level >100 nmol/L had greater forced vital capacity compared with those who had vitamin D level 50–100 nmol/L group in all the three models (model C: coefficient, 1.17; 0.18–2.15).
The findings indicate that respiratory illness and symptoms are related to lower vitamin D levels, researchers said.
Taken together with evidence from recent studies investigating asthma outcomes and use of vitamin D supplements, the data strengthen the proposed mechanistic relationship between vitamin D deficiency and respiratory disease, they added. [J Allergy Clin Immunol 2017;139:1508-1517; Cochrane Database Syst Rev 2016;9:CD011511]