Relationship between serum 25-hydroxyvitamin d and pulmonary function in the third national health and nutrition examination survey.

CONTEXT Age, gender, height, ethnicity, and smoking are important determinants of lung function but do not explain all of the variation between individuals. Low concentrations of vitamin D have been associated with a number of diseases, including osteoporosis, hypertension, and type I diabetes. It is possible that serum concentrations of vitamin D might also influence pulmonary function. OBJECTIVES To determine the relationship between serum concentrations of 25-hydroxy vitamin D and pulmonary function. DESIGN, SETTING AND PARTICIPANTS The analysis was conducted using data from the Third National Health and Nutrition Examination Survey, which was a cross-sectional survey of the US civilian population that was conducted from 1988 to 1994. The analyses were restricted to 14,091 people who > or = 20 years of age, were interviewed at mobile examination centers, and had undergone spirometry, and in whom serum 25-hydroxy vitamin D levels had been measured. RESULTS After adjustment for age, gender, height, body mass index, ethnicity, and smoking history, the mean FEV1 was 126 mL (SE, 22 mL), and the mean FVC was 172 mL (SE, 26 mL) greater for the highest quintile of serum 25-hydroxy vitamin D level (> or = 85.7 nmol/L) compared with the lowest quintile (< or = 40.4 nmol/L; p < 0.0001). With further adjustment for physical activity, the intake of vitamin D supplements, milk intake, and the level of serum antioxidants, the mean difference between the highest and lowest quintiles of 25-hydroxy vitamin D was 106 mL (SE, 24 mL) for FEV1, and 142 mL (SE, 29 mL) for FVC (p < 0.0001). CONCLUSIONS There is a strong relationship between serum concentrations of 25-hydroxy vitamin D, FEV1, and FVC. Further studies are necessary to determine whether supplementation with vitamin D is of any benefit in patients with respiratory disease.