Associations of Serum 25(OH)D Concentrations with Lung Function, Airway Inflammation and Common Cold in the General Population

Associations Between Phthalate, Eosinophil, and Aeroallergen Sensitization in Schoolchildren

BACKGROUND

Phthalates and bisphenol A (BPA) are endocrine-disrupting chemicals and may cause immunological disorders in children. Therefore, according to the region, we investigated urinary phthalates and BPA levels and the relationship between urinary phthalate, aeroallergen sensitization, and eosinophil count during the coronavirus disease 2019 pandemic.

METHODS

In total, 203 schoolchildren (134 residential and 69 industrial) aged 7-10 years were enrolled between July 2021 and July 2022. The BPA, metabolites of four high-molecular-weight phthalates (Σ4HMWP) and three low-molecular-weight phthalates (Σ3LMWP), were measured in the urine samples. Total eosinophil count and transepidermal water loss (TEWL) were also measured along with the skin prick test.

RESULTS

The two groups had no differences in terms of BPA. The industrial group had significantly more plastic container usage, and there was a difference in the Σ3LMWP (P < 0.001) between the two groups but no difference in the Σ4HMWP (P = 0.234). The quartiles of urinary Σ4HMWP and Σ3LMWP (P < were not associated with the total eosinophil count, vitamin D level, or TEWL. After adjusting for cofactors, the quartiles of urinary Σ4HMWP and Σ3LMWP were significantly associated with total eosinophil count (P < 0.001) but not with aeroallergen sensitization or vitamin D.

CONCLUSION

Exposure to phthalates was significantly associated with eosinophil count but not with aeroallergen sensitization or vitamin D. Therefore, reducing the use of plastic containers may effectively prevent exposure to phthalates and reduce Th2 cell-mediated inflammation in children.

Vitamin D: immune function, inflammation, infections and auto-immunity

Vitamin D plays an active role beyond mineral metabolism and skeletal health, including regulation of the immune system. Vitamin D deficiency is widely prevalent, and observational studies link low vitamin D status to a risk of infections and auto-immune disorders. Reports indicate an inverse relationship between vitamin D status and such conditions. This review details vitamin D signalling interactions with the immune system and provides experimental and clinical evidence evaluating vitamin D status, vitamin D supplementation and host susceptibility to infections, inflammation and auto-immunity. The published literature including related reviews, systematic reviews, meta-analyses, randomised controlled trials (RCTs), observational studies and basic science reports have been synthesised. Meta-analyses of observational studies have demonstrated a link between low vitamin D status and risk of acute respiratory infections, COVID-19 disorders, multiple sclerosis, type 1 diabetes (T1DM), inflammatory bowel disease (IBD), systemic lupus erythematosus and other auto-immune disorders. Observational studies suggest that vitamin D supplementation may protect against several infectious and auto-immune conditions. Meta-analyses of RCTs had mixed results, demonstrating a small protective role for vitamin D supplementation against acute respiratory infections, especially in those with vitamin D deficiency and children, and providing modest benefits for the management of T1DM and IBD. Vitamin D status is inversely associated with the incidence of several infectious and auto-immune conditions. Supplementation is recommended for those with vitamin D deficiency or at high risk of deficiency, and it might provide additional benefit in acute respiratory infections and certain auto-immune conditions.

The Role of Some Vitamins in Respiratory-related Viral Infections: A Narrative Review

This study aimed to find out the effect of vitamins on respiratory-related viral infections, including coronavirus disease 2019 (COVID-19), through the literature reviews. From January 2000 to June 2021, the studies (cohort studies, cross-sectional studies, case-control studies, randomized control trials) related to vitamins (vitamin A, D, E, C, B₆, folate, and B₁₂) and COVID-19/severe acute respiratory syndrome/Middle East respiratory syndrome/cold/influenza were selected from the PubMed, Embase, and Cochrane libraries and analyzed. The relationship between vitamins and virus-related respiratory diseases was identified. Through the review, 39 studies were selected on vitamin D, one study on vitamin E, 11 studies on vitamin C, and 3 studies on folate. Regarding COVID-19, 18 studies on vitamin D, 4 studies on vitamin C, and 2 studies on folate showed significant effects of the intake of these nutrients in preventing COVID-19. Regarding colds and influenza, 3 studies on vitamin D, 1 study on vitamin E, 3 studies on vitamin C, and 1 study on folate demonstrated that the intake of these nutrients significantly prevents these diseases. Therefore, this review suggested the intake of vitamins D, E, C, and folate is important for preventing respiratory diseases related to viruses, such as COVID-19, colds, and influenza. The relationship between these nutrients and virus-related respiratory diseases should be continuously monitored in the future.

Recent advances in vitamin D implications in chronic respiratory diseases

Chronic airway inflammatory and infectious respiratory diseases are the most common medical respiratory conditions, associated with significant morbidity and mortality. Vitamin D (1,25(OH)₂D₃) deficiency has been shown to be highly prevalent in patients with chronic airway inflammatory and infectious diseases, correlated with increased disease severity. It has been established that vitamin D modulates ongoing abnormal immune responses in chronic respiratory diseases and is shown to restrict bacterial and viral colonization into the lungs. On the contrary, other studies revealed controversy findings regarding vitamin D efficacy in respiratory diseases. This review aims to update the current evidence regarding the role of vitamin D in airway inflammation and in various respiratory diseases. A comprehensive search of the last five years of literature was conducted using MEDLINE and non-MEDLINE PubMed databases, Ovid MEDLINE, SCOPUS-Elsevier, and data from in vitro and in vivo experiments, including clinical studies. This review highlights the importance of understanding the full range of implications that vitamin D may have on lung inflammation, infection, and disease severity in the context of chronic respiratory diseases.

Nutrition as a modifiable factor in the onset and progression of pulmonary function impairment in COPD: a systematic review

CONTEXT

Chronic obstructive lung disease (COPD) is a progressive lung disease characterized by persistent airflow limitation. An increasing amount of evidence suggests an effect of dietary quality on the risk of COPD in the general population and pulmonary function decline in patients with COPD.

OBJECTIVE

The association of dietary intake and nutrient status with COPD risk and onset, as well as pulmonary function decline (change in forced expiratory volume in 1 second, forced vital capacity, or the ratio of the former to the latter) in patients with COPD was investigated in this systematic review.

DATA SOURCES

The PubMed database was searched by combining terms of pulmonary function or COPD with diet, nutrient status, or nutritional supplementation.

DATA EXTRACTION

Original studies and systematic reviews and meta-analyses were included. Articles obtained were independently screened for relevance on the bases of title and abstract by 2 researchers. Eventually, 89 articles were included in the analysis.

RESULTS

The unhealthy Western-style diet is associated with an increased risk of COPD and an accelerated decline of pulmonary function. Intake of fruit, vegetables, dietary fibers, vitamins C and E, polyphenols, and β-carotene were individually associated with lower COPD risk, whereas consumption of processed meat was associated with higher COPD risk. Data on the effect of dietary quality on pulmonary function decline in patients with COPD are limited and inconsistent. Strong evidence for beneficial effects on pulmonary function decline was found only for vitamin D supplementation.

CONCLUSION

Considering the increasing burden of COPD, more attention should be given to dietary quality as a modifiable factor in disease development and progression in patients with COPD.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021240183.

Serum vitamin D level is associated with smell dysfunction independently of aeroallergen sensitization, nasal obstruction, and the presence of allergic rhinitis in children

BACKGROUND

Smell dysfunction is highly prevalent worldwide and has adverse effects on quality of life. Smell loss in rhinitis subjects is mainly caused by mechanical obstruction of odorant transmission due to mucosal type 2 inflammation. We determined the association of 25-hydroxyvitamin D (25[OH]D) levels with the severity of smell dysfunction in children.

METHODS

We measured the olfactory threshold score in a total of 518 children (10-12 years old, 264 boys) using the Sniffin' Sticks kit, and the children were divided into tertiles according to olfactory threshold score. We also assessed serum 25[OH]D level, common aeroallergen-specific immunoglobulin E, rhinitis severity with visual analog scale, and the Total Four Symptom Score, and pre- and post-decongestant nasal patency with acoustic rhinometry.

RESULTS

The children with 25(OH)D deficiency had significantly reduced mean olfactory threshold scores when compared to those with 25(OH)D levels of ≥20.0 ng/mL (6.56 ± 3.54 and 7.28 ± 3.87, respectively, P = .036). The proportion of loss of smell function and pre-decongestant nasal patency significantly associated with low 25(OH)D levels (chi-square trend test, P for trend = .007). Likewise, after adjustment for confounders, children with smell loss (third tertile) were significantly associated with low 25(OH)D level (aβ=-0.062, 95% CI=-0.064 to -0.060, P = .009) independent of aeroallergen sensitization, and a low pre-decongestant nasal patency.

CONCLUSIONS

25-Hydroxyvitamin D is significantly associated with smell dysfunction independent of aeroallergen sensitization, nasal obstruction, and the presence of allergic rhinitis. This finding may provide insight into the mechanisms involved in the development of olfactory dysfunction.

Decreased lung function is associated with vitamin D deficiency in apparently health, middle aged Koreans: the Kangbuk Samsung Health Study

BACKGROUND/OBJECTIVES

There has been inconsistent relationships between serum vitamin D levels and lung function in previous studies. However, previous studies included patients with medical diseases, affecting both vitamin D levels and lung function. Considering this view of potential confounders, we investigated if vitamin D deficiency (VDD) is linked to lung function in health screening examinee without overt medical conditions.

SUBJECTS/METHODS

We conducted a cohort study on 68,457 healthy Koreans (36,759 males, mean age: 37.7 years) with a health examination in 2015. Measured forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were categorized in quartiles. To examine the relationships between VDD and lung function, adjusted odds ratios (aORs) for VDD were estimated by logistic regression.

RESULTS

Median vitamin D level was 14.9 ng/mL. The prevalence of VDD (defined as <20 ng/ml) was 74.5%. Compared with the highest quartile (Q4, reference), the aORs for VDD across decreasing quartiles (from Q3 to Q1) were 1.05, 1.06, 1.10 for FVC, and 1.07, 1.10, 1.10 for FEV1 (P for trend < 0.01 for both), in all subjects. Similarly, the aOR of having VDD for men also increased with decreasing quartiles of FVC and FEV1 in a dose-response manner (p for trend < 0.01 for both). However, neither FVC nor FEV1 was associated with VDD in women.

CONCLUSIONS

VDD was associated with decreased lung function in middle aged Korean men without overt medical conditions. VDD could be a modifiable risk factor for impaired lung function, in men but not in women.

Reduced Vitamin D Levels are Associated with Stroke-Associated Pneumonia in Patients with Acute Ischemic Stroke

Background and aim

Stroke-associated pneumonia (SAP) is a common complication in patients with acute ischemic stroke (AIS). This study explored the potential relationship between serum vitamin D levels and SAP.

Methods

This study recruited 863 consecutive AIS patients. In-hospital SAP was defined as a complication that occurred after stroke, during hospitalization, that was confirmed radiographically. Serum vitamin D levels were measured within 24 hrs of admission and the patients were divided into vitamin D sufficient (>50 nmol/L), insufficient (25–50 nmol/L), and deficient (<25 nmol/L) groups.

Results

In this study, 102 (11.8%) patients were diagnosed with SAP. Compared to the patients without SAP, patients with SAP had significantly lower vitamin D levels (P = 0.023). The incidence of SAP was significantly higher in patients with vitamin D deficiency than in those with vitamin D insufficiency or sufficiency (21.2% vs 16.2% & 9.5%, P = 0.006). After adjusting for confounders, vitamin D deficiency and insufficiency were independently associated with SAP (OR = 3.034, 95% CI = 1.207–7.625, P = 0.018; OR = 1.921, 95% CI = 1.204–3.066, P = 0.006, respectively). In multiple-adjusted spline regression, vitamin D levels showed a linear association with the risk of SAP (P < 0.001 for linearity).

Conclusion

Reduced vitamin D is a potential risk factor of in-hospital SAP, which can help clinicians identify high-risk SAP patients.

Association between micronutrient deficiency and acute respiratory infections in healthy adults: a systematic review of observational studies

Background

Acute respiratory infections (ARI), including the common cold causes significant morbidity and economical losses globally. Micronutrient deficiency may increase ARI incidence risk and its associated duration and severity among healthy adults, but evidence are inconclusive. This study aims to systematically review all observations on the association between single micronutrient deficiency and ARI incidence, duration and severity in healthy adults.

Methods

Systematic literature searches were conducted in PubMed, Cochrane Library, Embase and Scopus databases. Eligible studies were assessed for the reporting and methodological quality. Adjusted summary statistics with their relevant 95% confidence intervals or interquartile ranges were extracted for the outcomes of interest.

Results

The literature search identified 423 unique studies. Of which, only eight studies were eligible and included in the final review. Only vitamin D deficiency (VDD) was observed among these eight studies. There were no eligible studies that focused on the association between other single micronutrient deficiency and ARI. The review found mixed observations on ARI incidence, and a lack of evidence on its associated severity to conclude the association between VDD and these outcomes. However, existing evidence consistently suggested that VDD is likely to lead to longer ARI duration (median duration in days: deficient group, 4 to 13; non-deficient groups, 2 to 8).

Conclusion

This review found that VDD may be associated to longer ARI duration, but its effect on ARI incidence and its associated severity among healthy adults remains inconclusive. This review also highlighted the lack of a consistent regional and/or global definition for micronutrient sufficiency, and that future studies should explore and conclude the association between other micronutrient deficiency and ARIs in healthy adults before considering supplementation for ARI prevention and management.

Acute Respiratory Tract Infection and 25-Hydroxyvitamin D Concentration: A Systematic Review and Meta-Analysis

Observational studies and randomised controlled studies suggest that vitamin D plays a role in the prevention of acute respiratory tract infection (ARTI); however, findings are inconsistent and the optimal serum 25-hydroxyvitamin D (25(OH)D) concentration remains unclear. To review the link between 25(OH)D concentration and ARTI, we searched PubMed and EMBASE databases to identify observational studies reporting the association between 25(OH)D concentration and risk or severity of ARTI. We used random-effects meta-analysis to pool findings across studies. Twenty-four studies were included in the review, 14 were included in the meta-analysis of ARTI risk and five in the meta-analysis of severity. Serum 25(OH)D concentration was inversely associated with risk and severity of ARTI; pooled odds ratios (95% confidence interval) were 1.83 (1.42-2.37) and 2.46 (1.65-3.66), respectively, comparing the lowest with the highest 25(OH)D category. For each 10 nmol/L decrease in 25(OH)D concentration, the odds of ARTI increased by 1.02 (0.97-1.07). This was a non-linear trend, with the sharpest increase in risk of ARTI occurring at 25(OH)D concentration < 37.5 nmol/L. In conclusion, there is an inverse non-linear association between 25(OH)D concentration and ARTI.