Serum 25-hydroxyvitamin D level, smoking and lung function in adults: the HUNT Study

Abstract

The association between serum 25-hydroxyvitamin D (25(OH)D) level and lung function changes in the general population remains unclear.We conducted cross-sectional (n=1220) and follow-up (n=869) studies to investigate the interrelationship of serum 25(OH)D, smoking and lung function changes in a random sample of adults from the Nord-Trøndelag Health (HUNT) Study, Norway.Lung function was measured using spirometry and included forced expiratory volume in 1 s (FEV1) % predicted, forced vital capacity (FVC) % pred and FEV1/FVC ratio. Multiple linear and logistic regression models estimated the adjusted difference in lung function measures or lung function decline, adjusted odds ratios for impaired lung function or development of impaired lung function and 95% confidence intervals.40% of adults had serum 25(OH)D levels <50 nmol·L −1. Overall, those with a serum 25(OH)D level <50 nmol·L −1 showed worse lung function and increased odds of impaired lung function compared to the ⩾50 nmol·L −1 group. These associations tended to be stronger among ever-smokers, including greater decline in FEV1/FVC ratio and greater odds of the development of impaired lung function (FEV1/FVC <70% OR 2.4, 95% CI 1.2-4.9). Associations among never-smokers were null. Results from cross-sectional and follow-up studies were consistent. There were no associations between serum 25(OH)D levels and lung function or lung function changes in never-smokers, whereas significant associations were observed in ever-smokers.

No mediating effects of glycemic control and inflammation on the association between vitamin D and lung function in the general population

“…Firstly, among Korean subjects a positive correlation between 25(OH)D and lung function was found [12] which was confirmed in the present study as well as in the Framingham Heart Study [10]. However, among a large Danish population of 3471 subjects no relation between 25(OH)D levels and lung function was detected [9] and Larose et al [8], comparing non-smokers with smokers, also did not observed an association between serum 25(OH)D levels and lung function or changes in lung function among non-smokers, while significant associations became apparent among smokers. Moreover, in a longitudinal analysis of the Framingham Heart Study no relation between 25(OH)D levels and FEV 1 was observed.…”

Vitamin D Status of Severe COPD Patients with Chronic Respiratory Failure

“…No correlation was found of ventilatory parameters with 25(OH)D concentration in the study and control groups. Some researchers have reported statistically significant correlation in various subgroups of both controls and COPD patients [16][17][18]. The publications have lacked critical cause-and-effect analysis: decreased spirometric parameters have meant decreased physical fitness, less exposure to UV-B, and thus lower 25(OH)D concentrations.…”

“…The reason for not finding a correlation of ventilatory parameters with 25(OH)D concentration may be a relatively small number of participants in the study group in comparison to the quoted articles (NHANES: more than 10,000 participants). An alternative reason for lack of correlation between activity parameters and 25(OH)D concentrations might be accurate characteristics, homogenousness and narrowing of the study group (patients with very severe COPD in the stage of respiratory failure), while in other studies [16][17][18], the population was not limited to COPD and patients were in various stages of disease, which might have facilitated the observation of a connection.…”

“…Another study has revealed a significant correlation only in overweight and obese men [17]. In the Norwegian population, a chance increased 2.4 times for the abnormal FEV 1 /FVC% at the level of 25(OH)D <50 nmol/l, but this concerned active smokers only [18]. In patients diagnosed with COPD, emphysema or chronic bronchitis, a significantly lower 25(OH) D level was observed [19].…”

Serum 25-hydroxyvitamin D, vitamin D supplement and asthma control: The HUNT study

“…The intra-assay coefficient of variation and the inter-assay coefficient of variation of our samples were low, 4% and 8%, respectively. We categorized serum 25(OH)D as < 50, 50-74.9 and ≥ 75 nmol/L, and as per 25 nmol/L decrease based on previous literature [20][21][22][23].…”