Vitamin D deficiency, smoking, and lung function in the Normative Aging Study

Effect of vitamin D3 on the antimicrobial activity of human airway surface liquid: preliminary results of a randomised placebo-controlled double-blind trial

Introduction

Vitamin D₃ supplementation has been reported to prevent lung infections and increase the gene expression of antimicrobial peptides such as cathelicidin. We investigated the effect of vitamin D₃ supplementation on the antimicrobial activity of airway surface liquid (ASL) in human subjects. Since smoking can increase the risk of respiratory infections, we also investigated the effect of smoking in the cathelicidin response to vitamin D₃ in human airway epithelia in vitro.

Methods

This study is a subanalysis of single-centre community-based randomised placebo-controlled double-blind trial. Participants were randomised to receive 1000 international units per day of oral vitamin D₃ or identical placebo for 90 days. Blood and ASL samples were collected preintervention and postintervention. 105 participants were originally enrolled, 86 completed the trial, and due to low protein concentration in the samples, 40 participants were finally analysed. Our primary outcome was ASL antimicrobial activity. We also considered secondary outcomes including changes in serum concentration of 25-hydroxyvitamin D₃ (25(OH)D₃), 1,25-hydroxyvitamin D₃, calcium and parathyroid hormone (PTH). In addition, we studied the effect of cigarette smoke extract (CSE) exposure to primary human airway epithelial cell cultures on the gene expression of cathelicidin in response to vitamin D₃ and expression of CYP27B1 (1-alpha hydroxylase), responsible for vitamin D₃ activation.

Results

Vitamin D₃ supplementation significantly increased both ASL antimicrobial activity and serum concentration of 25(OH)D₃. In a subgroup analysis, we found that smokers did not increase their baseline antimicrobial activity in response to vitamin D₃. Exposure to CSE on human airway epithelia decreased baseline CYP27B1 gene expression and cathelicidin response to 25(OH)D₃.

Conclusion

Vitamin D₃ supplementation for 90 days increases ASL antimicrobial activity. Data from this preliminary study suggest that smoking may alter the ability of airway epithelia to activate vitamin D₃ and increase the gene expression of cathelicidin antimicrobial peptide.

Trial registration number

NCT01967628; Post-results.

Association between lutein intake and lung function in adults: the Rotterdam Study

Lutein, a fat-soluble carotenoid with antioxidant properties, may have an effect on respiratory health. However, the evidence is inconsistent. We aimed to cross-sectionally investigate the association between lutein intake and lung function by measuring forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC% in adults (aged 45-79 years). We included 4402 participants from the Rotterdam Study, a prospective cohort study in The Netherlands. Lutein intake was assessed using a validated FFQ. Lung function was assessed using spirometry around the same time point as the dietary assessment. No independent association was found between lutein intake and FEV1 (-12·17 (95 % CI -34·21, 9·87) ml per sd increase in lutein) after adjustment for age, sex, height, cohort effect, ethnicity, education, weight, total daily energy intake, smoking status, physical activity, and intakes of fatty acids, dietary fibre, alcohol, β-carotene, β-crypotoxanthin, lycopene and zeaxanthin. There was also no association between lutein and FVC or FEV1/FVC%. However, after stratification by smoking status, lutein intake was significantly associated with lower FEV1/FVC% in current smokers (-1·69 (95 % CI -2·93, -0·45) % per sd increase of lutein) independent of other carotenoids. The present study does not support an independent association between lutein intake and lung function in adults. However, future studies should focus on the potential inverse association between high lutein intake and lung function in specific risk groups such as smokers.

Vitamin D deficiency: What does it mean for chronic obstructive pulmonary disease (COPD)? a compherensive review for pulmonologists

OBJECTIVES

Vitamin D deficiency and Chronic Obstructive Pulmonary Disease (COPD) are both under-recognized health problems, world-wide. Although Vitamin D has long been known for calcemic effects it also has less known noncalcemic effects. Recent data have shown that Vitamin D deficiency is highly prevalent in patients with COPD and correlates with forced expiratory volume in one second (FEV₁ ) and FEV₁ decline. The objective of this work was to review the current literature on vitamin D deficiency in relation with COPD.

DATA SOURCE

A literature search, using the words "vitamin D" and "COPD", was undertaken in Pubmed database.

RESULTS

The noncalcemic effects of vitamin D relating with COPD may be summarised as increasing antimicrobial peptide production, regulation of inflammatory response and airway remodelling. Vitamin D inhibits the production of several proinflammatory cytokines and leads to suppression Th1 and Th17 responses which may be involved in the pathogenesis of COPD. Vitamin D insufficiency may also contribute to chronic respiratory infections and airway colonization so returning vitamin D concentrations to an optimal range in patients with COPD might reduce bacterial load and concomitant exacerbations.Vitamin D is also important for COPD-related comorbodities such as osteoporosis, muscle weakness and cardiovascular diseases. Data about the effect of Vitamin D supplementation on those comorbidities in relation with COPD are been scarce.

CONCLUSION

Improving the blood level of Vitamin D into the desired range may have a beneficial effect bones and muscles, but more studies are needed to test to test that hypothesis.

Modification of the association between smoking status and severity of coronary stenosis by vitamin D in patients suspected of coronary heart disease

Given both smoking and vitamin D are associated with coronary heart disease (CHD) via inflammation and smoking may interfere with the local antiinflammatory effects of vitamin D. We hypothesized that the relationship between smoking and severity of CHD may be modified by vitamin D.A cross-sectional study was conducted. 25-OH vitamin D values were determined in 348 consecutive patients (mean age 62.4 ± 10.5 years; 56.3% male) undergoing coronary angiography at the Heart Center of Chaoyang Hospital affiliated to Capital Medical University between the period of September 2014 and May 2015. We categorized the patients into 2 groups based on 25-OH vitamin D levels, that is, severe hypovitaminosis D (25-OH vitamin D < 10 ng/mL) and higher vitamin D (25-OH vitamin D > =  10 ng/mL). Multivariable logistic regression models were used to estimate odds ratios (ORs) of severe coronary stenosis or higher Gensini score across three smoking status, that is, never smokers, former smokers, and current smokers in severe hypovitaminosis D and higher vitamin D groups, respectively.Of these patients, we identified 212 (60.9%) cases of severe CHD and 161 (46.3%) cases of severe hypovitaminosis D. Multivariable logistic regression model showed the ORs of severe CHD were 1.94 (95% confidence interval [CI]: 0.47, 7.98) for former smokers and 2.62 (95% CI: 0.83, 8.24) for current smokers, compared with never smokers in group with severe hypovitaminosis D (P-trend = 0.005). In contrast, smoking was not found to be significantly associated with severe CHD in group with higher 25-OH vitamin D (P-trend = 0.115). We found a significant interaction between smoking status and vitamin D on presence of severe CHD (P-interaction = 0.015). In terms of Gensini score as a dependent variable, similar results were identified.Our finding indicated the association between smoking and severity of CHD appeared to be substantially stronger among patients with severe hypovitaminosis D as compared with those with higher vitamin D levels. This suggests vitamin D sufficiency may have a protective effect against the damaging effects of smoking on coronary artery. Future cohort studies are warranted to confirm this finding.

1,25-Dihydroxyvitamin D Modulates Antibacterial and Inflammatory Response in Human Cigarette Smoke-Exposed Macrophages

Cigarette smoking is associated with increased inflammation and defective antibacterial responses in the airways. Interestingly, vitamin D has been shown to suppress inflammation and to improve antibacterial defense. However, it is currently unknown whether vitamin D may modulate inflammation and antibacterial defects in human cigarette smoke (CS)-exposed airways. To explore these unresolved issues, alveolar macrophages obtained from non-smoking and smoking subjects as well as human cigarette smoke extract (CSE)-treated THP-1 macrophages were stimulated with 1,25-dihydroxyvitamin D (1,25(OH)2D) to address inflammatory and antibacterial responses. Although basal levels of inflammatory cytokines and chemokines did not differ between non-smoking and smoking subjects, 1,25(OH)2D did reduce levels of IL-6, TNF-α and MCP-1 in alveolar macrophages in response to LPS/IFN-γ, although not statistically significant for TNF-α and IL-6 in smokers. CSE did not significantly alter vitamin D metabolism (expression levels of CYP24A1 or CYP27B1) in THP-1 macrophages. Furthermore, stimulation with 1,25(OH)2D reduced mRNA expression levels and/or protein levels of IL-8, TNF-α and MCP-1 in CSE-treated THP-1 macrophages. 1,25(OH)2D did not improve defects in phagocytosis of E. coli bacteria or the oxidative burst response in CSE-treated THP-1 macrophages or alveolar macrophages from smokers. However, 1,25(OH)2D significantly enhanced mRNA expression and/or protein levels of the antimicrobial peptide cathelicidin in alveolar macrophages and THP-1 macrophages, independently of CS exposure. In conclusion, our results provide the first evidence that vitamin D could be a new strategy for attenuating airway inflammation and improving antibacterial defense in CS-exposed airways.

Sharpening nature's tools for efficient tuberculosis control: A review of the potential role and development of host-directed therapies and strategies for targeted respiratory delivery

Centuries since it was first described, tuberculosis (TB) remains a significant global public health issue. Despite ongoing holistic measures implemented by health authorities and a number of new oral treatments reaching the market, there is still a need for an advanced, efficient TB treatment. An adjunctive, host-directed therapy designed to enhance endogenous pathways and hence compliment current regimens could be the answer. The integration of drug repurposing, including synthetic and naturally occurring compounds, with a targeted drug delivery platform is an attractive development option. In order for a new anti-tubercular treatment to be produced in a timely manner, a multidisciplinary approach should be taken from the outset including stakeholders from academia, the pharmaceutical industry, and regulatory bodies keeping the patient as the key focus. Pre-clinical considerations for the development of a targeted host-directed therapy are discussed here.

Smoking and serum vitamin D in older Chinese people: cross-sectional analysis based on the Guangzhou Biobank Cohort Study

OBJECTIVE

Studies on serum vitamin D in smokers showed conflicting results. We examined the association of smoking status with serum vitamin D in older Chinese men, taking advantage of a community-based sample with natural exposure to vitamin D.

DESIGN

Cross-sectional study based on the Guangzhou Biobank Cohort Study (GBCS).

SETTING

Community-based sample from the Guangzhou Biobank Cohort Study.

PARTICIPANTS

612 male participants aged 50+years recruited from 2009 to 2011.

RESULTS

The mean (SD) of vitamin D concentration was 58.3 (17.2), 57.0 (15.0) and 54.7 (15.4) nmol/L for never, former and current smokers, respectively. Adjusted for multiple confounders, vitamin D decreased from never to former, then to current smokers (P for trend 0.02). Compared to never smokers, current smokers had lower serum concentrations of vitamin D, and the concentrations decreased with the increasing number of cigarettes per day (-3.11 (95% CI -9.05 to 2.82), -3.29 (-8.3 to 1.72) and -4.61 (-8.89 to -0.33) for 1-9, 10-19 and 20+cigarettes per day, respectively; p for trend 0.01), duration of smoking (-1.39 (-6.09 to 3.30) and -5.39 (-9.42 to -1.35) for 1-39 and 40+years, respectively; p for trend 0.008) as well as pack-years (-2.89 (-6.78 to 1.01) and -5.58 (-10.48 to -0.67) for 1-39 and 40+pack-years, respectively; p for trend 0.009). Longer duration of quitting smoking was associated with higher vitamin D than was current smoking (P for trend 0.04).

CONCLUSIONS

Current smokers had lower vitamin D than never smokers, and the association showed a dose-response pattern.

Vitamin D and Lung Function Decline in Adults With Asthma: The HUNT Study

We investigated whether low 25-hydroxyvitamin D (25(OH)D) levels were associated with more lung function decline in adults with asthma and whether this association was modified by smoking status or inhaled corticosteroid (ICS) use. We analyzed data on 395 adults with asthma from the Nord-Trøndelag Health Study (1995-2008), Norway. Plasma 25(OH)D and lung function were measured at baseline, and lung function measurements were repeated at follow-up, approximately 11 years later. Linear regression was used to estimate lung function decline. Participants with low 25(OH)D (<50 nmol/L) had more decline in lung function measurements for forced expiratory volume in 1 second (FEV1) (388 mL), forced vital capacity (298 mL), and the FEV1/forced vital capacity ratio (3.7%) over the follow-up, compared with those with high 25(OH)D (≥50 nmol/L) who declined 314 mL, 246 mL, and 3.0%, respectively (P = 0.08, 0.30, and 0.23, respectively). The associations were stronger in never smokers and non-ICS users. In never smokers, low 25(OH)D levels were associated with more decline in FEV1 (445 vs. 222 mL) (P = 0.01). In non-ICS users, low 25(OH)D levels were associated with more decline in FEV1 (467 vs. 320 mL) (P = 0.02). Low serum 25(OH)D levels were weakly associated with more lung function decline in adults with asthma, and stronger associations were observed in never smokers and non-ICS users.

The effect of cigarette smoking on vitamin D level and depression in male patients with acute ischemic stroke

OBJECTIVE

The association between low vitamin D levels and depression has been well documented in nonstroke subjects. Accumulating evidence shows that low vitamin D levels may be also associated with depression post stroke. Cigarette smoking was associated with lower vitamin D levels. The purposes of this study were to compare vitamin D levels in smokers to nonsmokers and examine the association between vitamin D levels and depression symptoms in patients with acute ischemic stroke.

MATERIALS AND METHODS

Serum levels of 25-hydroxyvitamin D [25(OH)D] were measured in 194 males within 24h after admission: 116 smokers and 78 nonsmokers. Depression symptoms were assessed with the 17-item Hamilton Depression Scale (HAMD-17). Patients with the HAMD-17 score >7 were identified to have depression symptoms.

RESULTS

The chi-square test showed that the frequency of depression in the smoker group was 23.3% (27/116), which was significantly higher than that in the nonsmoker group (11.5%=9/78), with an odds ratios (OR) of 2.33 (95% CI: 1.03-5.27; χ(2)=4.25, df=1, p=0.039, φ=0.15). Vitamin D levels were significantly lower in smokers than in nonsmokers (52.4±20.8 vs 61.7±19.2; F=9.88, p=0.002), with an effect size of 0.05 (ηp(2)). Patients with depression symptoms showed lower vitamin D levels than those with no depression symptoms (49.2±19.6 vs 57.7±20.6; F=5.03, p=0.03), with an effect size of 0.03 (ηp(2)).

CONCLUSION

Higher rates of depression in smokers with acute ischemic stroke may be associated with lower vitamin D levels induced by smoking.

Lung VITAL: Rationale, design, and baseline characteristics of an ancillary study evaluating the effects of vitamin D and/or marine omega-3 fatty acid supplements on acute exacerbations of chronic respiratory disease, asthma control, pneumonia and lung function in adults

Laboratory and observational research studies suggest that vitamin D and marine omega-3 fatty acids may reduce risk for pneumonia, acute exacerbations of respiratory diseases including chronic obstructive lung disease (COPD) or asthma, and decline of lung function, but prevention trials with adequate dosing, adequate power, and adequate time to follow-up are lacking. The ongoing Lung VITAL study is taking advantage of a large clinical trial-the VITamin D and OmegA-3 TriaL (VITAL)--to conduct the first major evaluation of the influences of vitamin D and marine omega-3 fatty acid supplementation on pneumonia risk, respiratory exacerbation episodes, asthma control and lung function in adults. VITAL is a 5-year U.S.-wide randomized, double-blind, placebo-controlled, 2 × 2 factorial trial of supplementation with vitamin D3 ([cholecalciferol], 2000 IU/day) and marine omega-3 FA (Omacor® fish oil, eicosapentaenoic acid [EPA]+docosahexaenoic acid [DHA], 1g/day) for primary prevention of CVD and cancer among men and women, at baseline aged ≥50 and ≥55, respectively, with 5107 African Americans. In a subset of 1973 participants from 11 urban U.S. centers, lung function is measured before and two years after randomization. Yearly follow-up questionnaires assess incident pneumonia in the entire randomized population, and exacerbations of respiratory disease, asthma control and dyspnea in a subpopulation of 4314 randomized participants enriched, as shown in presentation of baseline characteristics, for respiratory disease, respiratory symptoms, and history of cigarette smoking. Self-reported pneumonia hospitalization will be confirmed by medical record review, and exacerbations will be confirmed by Center for Medicare and Medicaid Services data review.

Relation between Vitamin D Deficiency and Severity of Chronic Obstructive Pulmonary Disease-A Case Control Study

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disorder characterized by irreversible and progressive limitation of expiratory airflow. COPD is now considered as a systemic disease with several extra-pulmonary manifestations which include osteoporosis, muscle weakness, arrhythmia, stroke, cancer etc. The role of vitamin D in skeletal integrity is well established. Role of it in several other diseases like autoimmune, infectious, respiratory and cardiovascular diseases has been increasingly recognised. Data on vitamin D status in COPD in Indian population was limited while those comparing vitamin D with stage, pack year and body mass index were lacking.

AIM

To assess Vitamin D in subjects with COPD and matched controls and also to study the variability in serum vitamin D levels with COPD disease characteristics.

MATERIALS AND METHODS

A total of 162 patients aged 18-65 years from south India presenting to kasturba hospital were included in the study. Serum 25- hydroxy-vitamin D were measured in 81 COPD patients (combined COPD stage A-D) and compared with 81 age and gender matched controls. Level < 20 ng/ml defined deficiency. Risk estimate with Odds ratio and association of COPD characteristics with Vitamin D was assessed using logistic regression analysis.

RESULTS

COPD patients had an increased risk for vitamin D deficiency compared to controls after adjustment for age and gender(OR =2.687 (1.40,5.13)). Variables associated with lower 25(OH) D levels in COPD patients were higher pack year (p=0.001), current smoking status (p=0.026), Low BMI (p=0.02), and GOLD stage III- IV (p=0.001).

CONCLUSION

COPD was associated with an increased risk of vitamin D deficiency, and there was a significant association between vitamin D levels and Combined COPD stage severity. Also, a higher pack year and a low BMI are associated with lower levels of vitamin D.

Can Vitamin D Supplementation in Addition to Asthma Controllers Improve Clinical Outcomes in Patients With Asthma?: A Meta-Analysis

Effects of vitamin D on acute exacerbation, lung function, and fraction of exhaled nitric oxide (FeNO) in patients with asthma are controversial. We aim to further evaluate the roles of vitamin D supplementation in addition to asthma controllers in asthmatics. From 1946 to July 2015, we searched the PubMed, Embase, Medline, Cochrane Central Register of Controlled Trials, and ISI Web of Science using "Vitamin D," "Vit D," or "VitD" and "asthma," and manually reviewed the references listed in the identified articles. Randomized controlled trials which reported rate of asthma exacerbations and adverse events, forced expiratory volume in 1 s (FEV1, % of predicted value), FeNO, asthma control test (ACT), and serum 25-hydroxyvitamin D levels were eligible. We conducted the heterogeneities test and sensitivity analysis of the enrolled studies, and random-effects or fixed-effects model was applied to calculate risk ratio (RR) and mean difference for dichotomous and continuous data, respectively. Cochrane systematic review software Review Manager (RevMan) was used to test the hypothesis by Mann-Whitney U test, which were displayed in Forest plots. Seven trials with a total of 903 patients with asthma were pooled in our final studies. Except for asthma exacerbations (I2 = 81%, χ2 = 10.28, P = 0.006), we did not find statistical heterogeneity in outcome measures. The pooled RR of asthma exacerbation was 0.66 (95% confidence interval: 0.32-1.37), but without significant difference (z = 1.12, P = 0.26), neither was in FEV1 (z = 0.30, P = 0.77), FeNO (z = 0.28, P = 0.78), or ACT (z = 0.92, P = 0.36), although serum 25-hydroxyvitamin D was significantly increased (z = 6.16, P < 0.001). Vitamin D supplementation in addition to asthma controllers cannot decrease asthma exacerbation and FeNO, nor improve lung function and asthma symptoms, although it can be safely applied to increase serum 25-hydroxyvitamin D levels.

Evaluation of vitamin D levels in allergic and non-allergic asthma

BACKGROUND AND OBJECTIVE

Some researches show that low vitamin D may play a role in asthma pathogenesis. The aim of this study was to evaluate the serum vitamin D level in asthmatics with different phenotypes and to determine its associations with lung function, IgE, eosinophil count and body mass index (BMI).

MATERIALS AND METHODS

The study population comprised 85 patients with asthma and 73 healthy persons. Patients with asthma were divided into groups according to phenotypes. Allergy was assessed using a skin prick test and measuring eosinophil count in peripheral blood and total IgE in serum. Lung function was evaluated by spirometry. Concentration of vitamin D (25(OH)D3) was measured using a commercial ELISA kit. Smoking history was assessed and BMI was calculated for all individuals.

RESULTS

The vitamin D level was lower in asthmatics than in the control group (14.36±0.57 vs. 22.13±0.84 ng/mL, P<0.01). There were no significant differences in the vitamin D level between the groups with allergic and non-allergic asthma (14.36±0.77 vs. 14.35±0.74 ng/mL). The low vitamin D level increased the risk of asthma 1.2 times (OR, 1.194; 95% CI, 1.109-1.286, P<0.01). The vitamin D level did not correlate with lung function and markers of allergy in asthmatic patients. The vitamin D level correlated with FEV1/FVC (rs=0.72, P<0.05) in smoking patients with asthma. Correlation between the vitamin D level and BMI was found in all studied subjects (rs=-0.18, P<0.05).

CONCLUSIONS

The vitamin D level was lower in asthmatic patients than in healthy individuals despite their hypersensitivity and increase risk of asthma. There was no relation between the vitamin D level and lung function, eosinophil count and total IgE level, whereas the lower vitamin D level was associated with higher BMI.

No association between vitamin D and atopy, asthma, lung function or atopic dermatitis: a prospective study in adults

Studies suggest that vitamin D may be involved in the pathogenesis of allergic disorders, asthma and decreased lung function. However, results are inconsistent and only few prospective studies have examined adults. The purpose of this study was to investigate the association of serum 25-hydroxy vitamin D (s25(OH)D) with atopy, atopic dermatitis (AD), asthma, wheezing and impaired lung function in a prospective study of Danish adults. A random sample of 3471 persons was examined in 2006-2008. Of these, 2308 were re-examined 5 years later. s25(OH)D and specific IgE against four common inhalant allergens were measured by standard procedures. Wheezing, asthma and AD were assessed from questionnaires and lung function was measured by spirometry. We found no statistically significant associations between s25(OH)D and prevalence or incidence of atopy, AD, asthma or wheezing. Associations with lung function were inconsistent. We conclude that vitamin D status does not influence these conditions in adults.

Vitamin D deficiency exacerbates COPD-like characteristics in the lungs of cigarette smoke-exposed mice

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by excessive inflammation and disturbed bacterial clearance in the airways. Although cigarette smoke (CS) exposure poses a major risk, vitamin D deficiency could potentially contribute to COPD progression. Many in vitro studies demonstrate important anti-inflammatory and antibacterial effects of vitamin D, but a direct contribution of vitamin D deficiency to COPD onset and disease progression has not been explored.

METHODS

In the current study, we used a murine experimental model to investigate the combined effect of vitamin D deficiency and CS exposure on the development of COPD-like characteristics. Therefore, vitamin D deficient or control mice were exposed to CS or ambient air for a period of 6 (subacute) or 12 weeks (chronic). Besides lung function and structure measurements, we performed an in depth analysis of the size and composition of the cellular infiltrate in the airways and lung parenchyma and tested the ex vivo phagocytic and oxidative burst capacity of alveolar macrophages.

RESULTS

Vitamin D deficient mice exhibited an accelerated lung function decline following CS exposure compared to control mice. Furthermore, early signs of emphysema were only observed in CS-exposed vitamin D deficient mice, which was accompanied by elevated levels of MMP-12 in the lung. Vitamin D deficient mice showed exacerbated infiltration of inflammatory cells in the airways and lung parenchyma after both subacute and chronic CS exposure compared to control mice. Furthermore, elevated levels of typical proinflammatory cytokines and chemokines could be detected in the bronchoalveolar lavage fluid (KC and TNF-α) and lung tissue (IP-10, MCP-1, IL-12) of CS-exposed vitamin D deficient mice compared to control mice. Finally, although CS greatly impaired the ex vivo phagocytic and oxidative burst function of alveolar macrophages, vitamin D deficient mice did not feature an additional defect.

CONCLUSIONS

Our data demonstrate that vitamin D deficiency both accelerates and aggravates the development of characteristic disease features of COPD. As vitamin D deficiency is highly prevalent, large randomized trials exploring effects of vitamin D supplementation on lung function decline and COPD onset are needed.

The association of serum 25-OH vitamin D with atopy, asthma, and lung function in a prospective study of Danish adults

BACKGROUND

Besides the important skeletal functions, it has been suggested that vitamin D is involved in the pathogenesis of allergy and asthma and related to lung function. However, previous studies are inconclusive.

OBJECTIVE

The purpose of this study was to investigate associations of serum levels of 25-hydroxy vitamin D (25(OH)D) with atopy, asthma, and lung function in a prospective study of Danish adults.

METHODS

This study included 4999 adults aged 30-60 years in 1999-2001. Three thousand and thirty-two of those included at baseline also participated at a follow-up examination 5 years later, and 3727 answered a 10-year follow-up questionnaire. Serum levels of (25(OH)D) were measured by high-performance liquid chromatography (HPLC) at baseline. No information on use of vitamin D supplements was available. Specific IgE against four common antigens was measured. Information about doctor-diagnosed asthma was obtained from questionnaires, and lung function (FEV1 and forced vital capacity) was measured by spirometry.

RESULTS

We found no significant associations of 25(OH)D with atopy and doctor-diagnosed asthma. However, we found that low levels of 25(OH)D were associated with lower FEV1 percentage predicted (FEV1%pred) in the cross-sectional analyses. The odds ratio (OR) of FEV1%pred < 80% among participants in the highest quartile of 25(OH)D compared with those in the lowest was 0.66 (95% confidence interval (CI): 0.49-0.74). In contrast, prospective analyses indicated an association between high levels of 25(OH)D at baseline and adverse changes in lung function. OR (95%CI) of incident FEV1%pred < 80% was 1.73 (1.06-2.82) in the highest quartile of 25(OH)D compared with the lowest.

CONCLUSIONS AND CLINICAL RELEVANCE

Our data indicates that 25(OH)D levels do not influence the development of asthma and allergy among adults. Further, the results did not consistently support that 25(OH)D levels associate with lung function. Randomized controlled trials are needed to further address this issue.

Association of 25-Hydroxyvitamin D status and genetic variation in the vitamin D metabolic pathway with FEV1 in the Framingham Heart Study

BACKGROUND

Vitamin D is associated with lung function in cross-sectional studies, and vitamin D inadequacy is hypothesized to play a role in the pathogenesis of chronic obstructive pulmonary disease. Further data are needed to clarify the relation between vitamin D status, genetic variation in vitamin D metabolic genes, and cross-sectional and longitudinal changes in lung function in healthy adults.

METHODS

We estimated the association between serum 25-hydroxyvitamin D [25(OH)D] and cross-sectional forced expiratory volume in the first second (FEV1) in Framingham Heart Study (FHS) Offspring and Third Generation participants and the association between serum 25(OH)D and longitudinal change in FEV1 in Third Generation participants using linear mixed-effects models. Using a gene-based approach, we investigated the association between 241 SNPs in 6 select vitamin D metabolic genes in relation to longitudinal change in FEV1 in Offspring participants and pursued replication of these findings in a meta-analyzed set of 4 independent cohorts.

RESULTS

We found a positive cross-sectional association between 25(OH)D and FEV1 in FHS Offspring and Third Generation participants (P=0.004). There was little or no association between 25(OH)D and longitudinal change in FEV1 in Third Generation participants (P=0.97). In Offspring participants, the CYP2R1 gene, hypothesized to influence usual serum 25(OH)D status, was associated with longitudinal change in FEV1 (gene-based P<0.05). The most significantly associated SNP from CYP2R1 had a consistent direction of association with FEV1 in the meta-analyzed set of replication cohorts, but the association did not reach statistical significance thresholds (P=0.09).

CONCLUSIONS

Serum 25(OH)D status was associated with cross-sectional FEV1, but not longitudinal change in FEV1. The inconsistent associations may be driven by differences in the groups studied. CYP2R1 demonstrated a gene-based association with longitudinal change in FEV1 and is a promising candidate gene for further studies.

Vitamin D Deficiency and Insufficiency in Hospitalized COPD Patients

Introduction

31–77% of patients with COPD have vitamin D deficiency and insufficiency, with results being highly variable between studies. Vitamin D may also correlate with disease characteristics.

Aim

To find out the prevalence of vitamin D deficiency and insufficiency in patients with COPD admitted for exacerbation and a risk factors for lower vitamin D levels among comorbidities and COPD characteristics.

Methods

152 patients were studied for vitamin D serum levels (25(OH)D). All of them were also assessed for diabetes mellitus (DM) and metabolic syndrome (MS). Data were gathered also for smoking status and exacerbations in last year. All patients completed CAT and mMRC questionnaires and underwent spirometry.

Results

A total of 83,6% of patients have reduced levels of vitamin D. 42,8% (65/152) have vitamin D insufficiency (defined as 25–50 nmol/L) and 40,8% (62/152) have vitamin D deficiency (<25 nmol/L). The mean level of 25(OH)D for all patients is 31,97 nmol/L (95%CI 29,12–34,68). Vitamin D deficiency and insufficiency are more prevalent in females vs. males (97,7 vs 77,8%; p = 0.003). The prevalence and severity of vitamin D deficiency and insufficiency in this study is significantly higher when compared to an unselected Bulgarian population (prevalence 75,8%; mean level 38,75 nmol/L). Vitamin D levels correlate with quality of life (measured by the mMRC scale) and lung function (FVC, FEV1, FEV6, FEF2575, FEV3, but not with FEV1/FVC ratio and PEF), it does not correlate with the presence of arterial hypertension, DM, MS and number of moderate, severe and total exacerbations. Vitamin D deficiency is a risk factor for longer hospital stay.

Conclusions

The patients with COPD admitted for exacerbation are a risk group for vitamin D deficiency and insufficiency, which is associated with worse disease characteristics.

Novel epigenetic changes unveiled by monozygotic twins discordant for smoking habits

Exposure to cigarette smoking affects the epigenome and could increase the risk of developing diseases such as cancer and cardiovascular disorders. Changes in DNA methylation associated with smoking may help to identify molecular pathways that contribute to disease etiology. Previous studies are not completely concordant in the identification of differentially methylated regions in the DNA of smokers. We performed an epigenome-wide DNA methylation study in a group of monozygotic (MZ) twins discordant for smoking habits to determine the effect of smoking on DNA methylation. As MZ twins are considered genetically identical, this model allowed us to identify smoking-related DNA methylation changes independent from genetic components. We investigated the whole blood genome-wide DNA methylation profiles in 20 MZ twin pairs discordant for smoking habits by using the Illumina HumanMethylation450 BeadChip. We identified 22 CpG sites that were differentially methylated between smoker and non-smoker MZ twins by intra-pair analysis. We confirmed eight loci already described by other groups, located in AHRR, F2RL3, MYOG1 genes, at 2q37.1 and 6p21.33 regions, and also identified several new loci. Moreover, pathway analysis showed an enrichment of genes involved in GTPase regulatory activity. Our study confirmed the evidence of smoking-related DNA methylation changes, emphasizing that well-designed MZ twin models can aid the discovery of novel DNA methylation signals, even in a limited sample population.

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

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.

Innate immune modulation in chronic obstructive pulmonary disease: moving closer toward vitamin D therapy

Chronic obstructive pulmonary disease (COPD) is one of the most common respiratory diseases and a major cause of morbidity and mortality worldwide. Disturbed innate immune processes characterize the pathogenesis of COPD. Vitamin D deficiency is very common in COPD patients and has been associated with disease severity. Interestingly, mechanistic evidence from animal and in vitro studies has demonstrated important innate immunomodulatory functions of vitamin D, including anti-inflammatory, antioxidative, and antimicrobial functions. This review discusses in detail how the innate immunomodulatory functions of vitamin D may have therapeutic potential in COPD patients. The remaining challenges associated with vitamin D therapy in COPD patients are also discussed.

Vitamin D, vitamin D binding protein, and longitudinal outcomes in COPD

Background

Associations between Vitamin D₃ [25(OH)D], vitamin D binding protein (VDBP) and chronic obstructive pulmonary disease (COPD) are previously reported. We aimed to further investigate these associations on longitudinal outcomes.

Methods

426 COPD patients from western Norway, GOLD stage II-IV, aged 40–76, were followed every six-month from 2006 through 2009 with spirometry, bioelectrical impedance measurements and registration of exacerbation frequency. Serum 25(OH)D and VDBP levels were determined at study-entry by high-performance liquid chromatography coupled with mass spectrometry and enzyme immunoassays respectively. Yearly change in lung function and body composition was assessed by generalized estimating equations (GEE), yearly exacerbation rate by negative binomial regression models, and 5 years all-cause mortality by Cox proportional-hazard regression.

Results

1/3 of the patients had vitamin D deficiency (<20ng/mL) and a greater decline in both FEV1 and FVC, compared to patients with normal levels; for FEV1 this difference only reached statistical significance in the 28 patients with the lowest levels (<10ng/mL, p = 0.01). Neither 25(OH)D nor VDBP levels predicted exacerbation rate, change in fat free mass index or risk of death.

Conclusion

Severe vitamin D deficiency may affect decline in lung function parameters in COPD. Neither 25(OH)D nor VDBP levels did otherwise predict markers of disease progression.

Vitamin D as an adjunctive therapy in asthma. Part 2: A review of human studies

Vitamin D deficiency (VDD) is highly prevalent worldwide, with adverse effects on bone health but also potentially other unfavorable consequences. VDD and asthma-incidence/severity share many common risk factors, including winter season, industrialization, poor diet, obesity, dark skin pigmentation, and high latitude. Multiple anatomical areas relevant to asthma contain both the enzyme responsible for producing activated vitamin D and the vitamin D receptor suggesting that activated vitamin D (1,25-dihydroxyvitamin D) may have important local effects at these sites. Emerging evidence suggests that VDD is associated with increased airway hyperresponsiveness, decreased pulmonary function, worse asthma control, and possibly decreased response to standard anti-asthma therapy. However the effect is inconsistent with preliminary evidence from different studies suggesting vitamin D is both beneficial and detrimental to asthma genesis and severity. Current evidence suggests that supplementation with moderate doses of vitamin D may be appropriate for maintenance of bone health in asthmatics, particularly steroid users. However emerging data from an increasing number of randomized, controlled, intervention studies of vitamin D supplementation in pediatric and adult asthma are becoming available and should help determine the importance, if any of vitamin D for asthma pathogenesis. The purpose of this second of a two-part review is to review the current human literature on vitamin D and asthma, discussing the possible consequences of VDD for asthma and the potential for vitamin D repletion as adjunct therapy.

Association Between Vitamin D Status and Weaning From Prolonged Mechanical Ventilation in Survivors of Critical Illness

BACKGROUND

In this study, we examined the association between 25-hydroxyvitamin D (25(OH)D) concentration and successful weaning from mechanical ventilation in a cohort of ICU survivors requiring prolonged mechanical ventilation.

METHODS

This was a retrospective cohort study of ICU survivors admitted to a long-term acute care hospital. Demographic data were extracted from medical records, including 25(OH)D concentrations drawn on admission. Subjects were divided into 2 groups based on their 25(OH)D concentrations (deficient, < 20 ng/mL; not deficient, ≥ 20 ng/mL), and associations between 25(OH)D concentration and successful weaning were calculated.

RESULTS

A total of 183 subjects were studied. A high prevalence of 25(OH)D deficiency was found (61%, 111/183). No association was found between 25(OH)D concentration and weaning from mechanical ventilation. Increased comorbidity burden (Charlson comorbidity index) was associated with decreased odds of weaning (odds ratio of 0.50, 95% CI 0.25-0.99, P = .05).

CONCLUSIONS

Vitamin D deficiency is common in ICU survivors requiring prolonged mechanical ventilation. Surprisingly, there was no significant relationship between 25(OH)D concentration and successful weaning. This finding may be due to the low 25(OH)D concentrations seen in our subjects. Given what is known about vitamin D and lung function and given the low vitamin D concentrations seen in patients requiring long-term ventilatory support, interventional studies assessing the effects of 25(OH)D supplementation in these patients are needed.

COPD: balancing oxidants and antioxidants

Chronic obstructive pulmonary disease (COPD) is one of the most common chronic illnesses in the world. The disease encompasses emphysema, chronic bronchitis, and small airway obstruction and can be caused by environmental exposures, primarily cigarette smoking. Since only a small subset of smokers develop COPD, it is believed that host factors interact with the environment to increase the propensity to develop disease. The major pathogenic factors causing disease include infection and inflammation, protease and antiprotease imbalance, and oxidative stress overwhelming antioxidant defenses. In this review, we will discuss the major environmental and host sources for oxidative stress; discuss how oxidative stress regulates chronic bronchitis; review the latest information on genetic predisposition to COPD, specifically focusing on oxidant/antioxidant imbalance; and review future antioxidant therapeutic options for COPD. The complexity of COPD will necessitate a multi-target therapeutic approach. It is likely that antioxidant supplementation and dietary antioxidants will have a place in these future combination therapies.

Serum 25-hydroxyvitamin D levels and lung function in adults with asthma: the HUNT Study

The association between vitamin D status and lung function in adults with asthma remains unclear. We studied this cross-sectional association and possible modification by sex and allergic rhinitis in 760 adults (aged 19-55 years) with self-reported asthma in the Nord-Trøndelag Health Study. Serum 25-hydroxyvitamin D (25(OH)D) level <50 nmol·L(-1) was considered deficient. Lung function measurements included forced expiratory volume in 1 s (FEV1) % predicted, forced vital capacity (FVC) % predicted and FEV1/FVC ratio. Multiple linear regression models were used to estimate adjusted regression coefficients (β) and 95% confidence intervals. 44% of asthma adults had serum 25(OH)D levels <50 nmol·L(-1). Its associations with lung function measures seemed to be modified by sex and allergic rhinitis (p<0.03 for three-way interaction term). Overall, a serum 25(OH)D level <50 nmol·L(-1) was not associated with lung function measurements in subjects with allergic rhinitis in this asthma cohort. In men with asthma but without allergic rhinitis, however, a serum 25(OH)D level <50 nmol·L(-1) was significantly associated with lower FEV1/FVC ratio (β=-8.60%; 95% CI: -16.95%- -0.25%). Low serum 25(OH)D level was not associated with airway obstruction in most asthma adults with the exception of men with asthma but without allergic rhinitis.

Nutritional assessment and therapy in COPD: a European Respiratory Society statement

Nutrition and metabolism have been the topic of extensive scientific research in chronic obstructive pulmonary disease (COPD) but clinical awareness of the impact dietary habits, nutritional status and nutritional interventions may have on COPD incidence, progression and outcome is limited. A multidisciplinary Task Force was created by the European Respiratory Society to deliver a summary of the evidence and description of current practice in nutritional assessment and therapy in COPD, and to provide directions for future research. Task Force members conducted focused reviews of the literature on relevant topics, advised by a methodologist. It is well established that nutritional status, and in particular abnormal body composition, is an important independent determinant of COPD outcome. The Task Force identified different metabolic phenotypes of COPD as a basis for nutritional risk profile assessment that is useful in clinical trial design and patient counselling. Nutritional intervention is probably effective in undernourished patients and probably most when combined with an exercise programme. Providing evidence of cost-effectiveness of nutritional intervention is required to support reimbursement and thus increase access to nutritional intervention. Overall, the evidence indicates that a well-balanced diet is beneficial to all COPD patients, not only for its potential pulmonary benefits, but also for its proven benefits in metabolic and cardiovascular risk.

Influence of diet and obesity on COPD development and outcomes

The global increase in the prevalence and incidence of obesity has called serious attention to this issue as a major public health concern. Obesity is associated with many chronic diseases, including cardiovascular disease and diabetes, and recently the role of overweight and obesity in lung disease has received new interest. Independently of obesity, diet also plays a role as a risk factor for many chronic diseases, and evidence is accumulating to support a role for diet in the prevention and management of several lung diseases. Chronic obstructive lung disease is the third-leading cause of death globally, and both obesity and diet appear to play roles in its pathophysiology. Obesity has been associated with decreased lung-function measures in population-based studies, with increased prevalence of several lung diseases and with compromised pulmonary function. In contrast, obesity has a protective effect against mortality in severe chronic obstructive pulmonary disease (COPD). Nutrient intake and dietary patterns have also been associated with lung-function measures and the development and progression of COPD. Taken together, this suggests that a focus on obesity and diet should be part of public health campaigns to reduce the burden of lung disease, and could have important implications for clinicians in the management of their patients. Future research should also focus on elucidating these relationships in diverse populations and age-groups, and on understanding the complex interaction between behavior, environment, and genetics in the development and progression of COPD. The goal of this article is to review current evidence regarding the role that obesity and diet play in the development of COPD, and in COPD-related outcomes.

Cigarette smoke exposure is associated with vitamin D3 deficiencies in patients with chronic rhinosinusitis

BACKGROUND

Cigarette smoke (CS) plays a role in the exacerbation of chronic rhinosinusitis (CRS); however, the mechanism for this is unknown. We hypothesize that CS impairs human sinonasal epithelial cell (HSNEC) conversion of 25(OH)D3 (25VD3) to 1,25-dihydroxyvitamin D3 (1,25VD3) and, furthermore, that supplementation with 1,25VD3 will reverse smoke-induced inflammatory responses by HSNECs.

OBJECTIVE

We sought to determine the effect of CS on vitamin D3 (VD3) levels, conversion, and regulation of CS-induced inflammation in control subjects and patients with CRS.

METHODS

Blood and sinus tissue explants were collected at the time of surgery from control subjects, patients with chronic rhinosinusitis without nasal polyps, and patients with chronic sinusitis with nasal polyps (CRSwNP). Expression of VD3 metabolizing enzymes were measured by using RT-PCR. Primary HSNECs were cultured from tissue explants. 25VD3 with and without cigarette smoke extract (CSE) was used to examine conversion of 25VD3 to 1,25VD3, as well as HSNEC production of proinflammatory cytokines.

RESULTS

CS exposure was associated with reduced circulating and sinonasal 25VD3 levels in all groups compared with those seen in CS-naive, disease-matched counterparts. CS exposure decreased expression of CYP27B1 and was especially pronounced in patients with CRSwNP. CSE impairs control HSNEC conversion of 25VD3. HSNECs from patients with CRSwNP also demonstrate an intrinsic reduction in conversion of 25VD3 to 1,25VD3. Exogenous 1,25VD3 reduces CSE-induced cytokine production by HSNECs.

CONCLUSIONS

Exposure to CS is associated with reduced 25VD3 levels and an impaired ability of HSNECs to convert 25VD3 to 1,25VD3. Addition of 1,25VD3 reduces the proinflammatory effects of CS on HSNECs. Impaired VD3 conversion by CS exposure represents a novel mechanism through which CS induces its proinflammatory effects.

A cross sectional analysis of the role of the antimicrobial peptide cathelicidin in lung function impairment within the ALIVE cohort

BACKGROUND

Vitamin D deficiency is associated with reduced lung function. Cathelicidin, an antimicrobial peptide regulated by vitamin D, plays a role within the innate immune system. The association of cathelicidin with lung function decrement and respiratory infection is undefined. We determined the independent relationship of cathelicidin with lung function.

METHODS

In a cross-sectional analysis of 650 participants in an urban observational cohort with high smoking prevalence, plasma 25(OH)-vitamin D and cathelicidin levels were measured from stored samples obtained within 6 months of spirometry study visits. Multivariable linear regression was used to determine the independent association between low cathelicidin (defined as the lowest quartile of the cohort) and absolute forced expiratory volume in 1 second (FEV1).

RESULTS

The mean age of the cohort was 49 years; 91% were black, 35% female and 41% HIV-infected. Participants with low cathelicidin had a 183 mL lower FEV1 compared to higher cathelicidin (p = 0.009); this relationship was maintained (115 ml lower; p = 0.035) after adjusting for demographics, BMI, and smoking. Neither HIV serostatus, heavy smoking history, nor 25(OH)-vitamin D levels were associated with cathelicidin levels. Participants with low cathelicidin had a greater prevalence of prior bacterial pneumonia (21% versus 14%; p = 0.047). Inclusion of pneumonia in adjusted models did not substantially reduce the FEV1 decrement observed with low cathelicidin (104 mL lower FEV1; p = 0.05). Lung function decrements associated with low cathelicidin were greatest among individuals with lower 25(OH)-vitamin D levels.

CONCLUSIONS

In a cohort at risk for airflow obstruction, low cathelicidin was independently associated with lower FEV1. These clinical data support a mechanistic link between 25(OH)-vitamin D deficiency and lung function impairment, independent of pneumonia risk.

Profiles of vitamin D insufficiency and deficiency in Japanese men and women: association with biological, environmental, and nutritional factors and coexisting disorders: the ROAD study

Assessments of serum 25-hydroxyvitamin D levels in 1,683 Japanese from a population-based cohort revealed prevalences of vitamin D insufficiency and deficiency were 81.3 and 1.2%, respectively. Vitamin D deficiency was significantly associated with female sex, examined month, current smoking, lack of regular walking, higher intact parathyroid hormone (iPTH), and poor daily vitamin D intake.

INTRODUCTION

To clarify the characteristics of subjects with vitamin D insufficiency and deficiency among men and women in the general Japanese population.

METHODS

We initiated research on osteoarthritis/osteoporosis against disability (ROAD), a large-scale population-based cohort study, in 2005-2007. Blood examination was performed to measure serum 25-hydroxyvitamin D (25D) and iPTH levels and biochemical markers of bone turnover in 1,683 participants (595 men, 1,088 women). Participants completed an interviewer-administered questionnaire, measurements of bone mineral density, and x-ray examination. Vitamin D deficiency and insufficiency were defined by serum 25D levels <10 and ≥10 but <30 ng/mL, respectively.

RESULTS

The prevalence of vitamin D insufficiency and deficiency was 81.3 and 1.2%, respectively. Multinominal logistic regression analyses using potentially confounding variables revealed vitamin D insufficiency was significantly associated with age (+1 year, relative risk ratio, 0.98; 95% confidence interval, 0.96-0.99), gender (women vs. men, 2.28; 1.59-3.30), residing areas (coastal area vs. mountainous area, 0.58; 0.41-0.81), examined month (October, November, December vs. January, 0.51; 0.34-0.76), and serum levels of iPTH (+1 pg/mL, 1.02; 1.01-1.03). Vitamin D deficiency was significantly characterised by female sex (20.5; 3.1-136.7), examined month (0.28; 0.09-0.95), current smoking habit (6.39; 1.78-23.0), lack of regular outside walking (3.96; 1.34-11.7), higher iPTH (1.02; 1.01-1.03) and poor daily vitamin D intake (+10 μg/day, 0.48; 0.24-0.93).

CONCLUSIONS

A high prevalence of vitamin D insufficiency and a low prevalence of vitamin D deficiency were found in Japanese men and women, and the characteristics of vitamin D status were clarified.

Diet and vitamin D as risk factors for lung impairment and COPD

Epidemiologic and observational studies have shown an association between increased intakes of certain micronutrients and higher levels of lung function and health. The National Health and Nutrition Examination Surveys of the U.S. population have demonstrated repeatedly that increased intakes or serum levels of some micronutrients, including the vitamins E, D, C, and A, and carotenes are associated positively with forced expiratory volume in 1 second (FEV1). These findings are complemented by other observational studies, including the MORGEN study as well as the Seven Countries Study, both of which found micronutrient status had positive correlations with pulmonary function. In addition, epidemiologic studies have demonstrated that dietary intake patterns with increased intakes of fruit, vegetables, fish, vitamin E, and whole grains have been associated with a decreased development of chronic obstructive pulmonary disease (COPD) in smokers and nonsmokers, higher levels of FEV1, and decreased long-term COPD mortality. Diets high in refined food have been associated with accelerated longitudinal decline in FEV1 over 5 years. Taken together, these results suggest that micronutrient status may impact lung function, and that nutrition interventions could be a useful tool in a public health campaign aimed at the prevention of lung disease. Future research should focus on the effect of nutrition interventions on the natural history of lung disease.

Plasma 25-hydroxyvitamin D associated with pulmonary function in Canadian adults with excess adiposity

BACKGROUND

Vitamin D deficiency is an important health issue, particularly among people residing in northern countries. Low concentrations of 25-hydroxyvitamin D [25(OH)D] have been linked to several health conditions.

OBJECTIVE

The objective was to determine the association between plasma 25(OH)D and pulmonary function and the effect modifications of sex and body mass index (BMI) in adults.

DESIGN

A cross-sectional study included 3359 adults aged ≥18 y who participated in the Canadian Health Measures Survey, and a 2-stage multiple linear regression analysis was conducted.

RESULTS

Overall, 26% of the adults had a plasma 25(OH)D concentration <50 nmol/L, which is considered deficient (ie, hypovitaminosis D). This deficiency was more prevalent among men than among women (30% compared with 23%). Regression analysis showed that deficient plasma 25(OH)D was associated with lower mean residual forced vital capacity and forced expiratory volume in 1 s in men after adjustment for covariates. When further stratified by BMI, the associations were more marked in overweight and obese men. Vitamin D deficiency associated with pulmonary function was not statistically significant in normal-weight men or in women, regardless of BMI categories. Similar results were obtained when plasma 25(OH)D was examined as a continuous variable in the models.

CONCLUSIONS

Hypovitaminosis D may be a risk factor for lung dysfunction, especially for overweight and obese men. Further research is necessary to determine the mechanism of the interrelation between vitamin D, adiposity, and pulmonary function.

Vitamin D and chronic obstructive pulmonary disease: hype or reality?

Abundant laboratory findings show the important role vitamin D has in the innate and adaptive immune system. In human beings, observational studies have associated vitamin D deficiency with an increased risk for different inflammatory, infectious, and autoimmune diseases. With regard to chronic obstructive pulmonary disease (COPD), conflicting data have been reported. Most epidemiological studies have been restricted by their design, and larger longitudinal studies of population-based samples and of cohorts with COPD are warranted. An alternative explanation for the discordant results in COPD might be related to the complexity of the intracellular vitamin D signalling pathway, which is not shown in systemic levels of the precursor 25-hydroxyvitamin D. For COPD in particular, we speculate that local downregulation of vitamin D signalling from and beyond the receptor might clarify why pro-inflammatory processes in the airways are not or are insufficiently countered by vitamin D-dependent control mechanisms. In a disease already characterised by glucocorticoid resistance, the potential activation and reactivation of an intrinsic comprehensive system of immune control should attract more attention to design appropriate interventions with promising therapeutic potential.

Relationship between serum 25-hydroxyvitamin D and lung function among Korean adults in Korea National Health and Nutrition Examination Survey (KNHANES), 2008-2010

CONTEXT

The relationship between vitamin D status and pulmonary function has not been investigated for an East Asian population.

OBJECTIVE

The aim of the present study was to examine the relationship of serum 25-hydroxyvitamin D [25(OH)D] with lung function in Korean adults.

DESIGN AND SETTING

The analysis used data from the Korea National Health and Nutrition Examination Survey (KNHANES), a cross-sectional survey of Korean civilians, conducted from 2008 to 2010.

PARTICIPANTS

A total of 10 096 people aged 19 years and older were selected from 16 administrative districts in South Korea.

MAIN OUTCOME MEASURES

Serum 25(OH)D levels with lung function [forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC)].

RESULTS

Serum 25(OH)D concentration was positively associated with lung function after controlling for age, sex, height, and season. For FEV1 and FVC, the differences between top and bottom quartiles in 25(OH)D were 51 mL (SE, 17 mL, P trend <.001) and 58 mL (SE, 20 mL, P trend <.005) greater volume, respectively. Association of serum 25(OH)D with FEV1 and FVC was only slightly attenuated after adjustment for body mass index, lifestyle and socioeconomic factors, and respiratory illness. The subjects with a history of pulmonary tuberculosis showed a much higher increase in FEV1; the difference between top and bottom quartiles in 25(OH)D was 229 mL (SE, 87 mL, P trend <.01).

CONCLUSION

Serum 25(OH)D levels have a positive correlation with pulmonary function. This relationship appears prominent in subjects with susceptibility to pulmonary tuberculosis.

Effect of duration of exposure to cement dust on respiratory function of non-smoking cement mill workers

This study aimed to determine the effect of long term exposure to cement dust on lung function in non-smoking cement mill workers. This is a cross-sectional study of respiratory functions. Spirometry was performed in 100 apparently healthy volunteers; 50 non-smoking cement mill workers and 50 non-smoking un-exposed subjects. Based on the duration of exposure, cement mill workers were divided into three groups, less than 5, 5–10 and greater than 10 years. All subjects were individually matched for age, height, weight, and socioeconomic status. Pulmonary function test was performed by using an electronic spirometer. Significant reduction was observed in the mean values of Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV₁), Peak Expiratory Flow (PEF) and Maximal Voluntary Ventilation in cement mill workers who had been working in the cement industry for more than 10 years compared to their matched un-exposed group. Lung functions in cement mill workers were significantly impaired and results show a long term duration response effect of years of exposure to cement dust on lung functions.