Vitamin D and asthma in children: A systematic review and meta-analysis of observational studies

A 12-week double-blind randomised controlled trial investigating the effect of dietary supplementation with 125 μg/d vitamin D in adults with asthma

Vitamin D deficiency has previously been linked to higher rates of exacerbation and reduced lung function in asthmatics. Previous randomised controlled trials investigating the effect of vitamin D supplementation have mainly focused on children with asthma. Trials involving adults have typically used bolus dosing regimens, and the main outcomes have been patient-focused without investigating underlying inflammation. The present study aimed to conduct a 12-week placebo-controlled randomised controlled trials administering a daily 125 µg vitamin D3 supplement to adults with mild to moderate asthma. A total of 32 participants were randomised to receive either the 125 μg vitamin D3 supplement or an identical matching placebo. The primary outcome of the study was lung function measured by the ratio of FEV1:FVC (effect size 2·5) with secondary outcomes including asthma symptoms and inflammatory biomarkers. There was a small but statistically significant higher increase in the mean (±sd) ratio of FEV1:FVC from baseline to post-intervention in the vitamin D group (+0·05 ± 0·06) compared with the placebo group (+0·006 ± 0·04, P = 0·04). There was no effect of the intervention on asthma control test scores, or the inflammatory biomarkers measured. There was a moderate, significant association between baseline plasma 25(OH)D concentration and baseline plasma IL-10 (r = 0·527, P = 0·005) and TNF-α (r = −0·498. P = 0·008) concentrations. A daily vitamin D3 supplement led to slightly improved lung function in adult asthmatics and may be a useful adjunct to existing asthma control strategies, particularly for individuals with suboptimal vitamin D status.

The serum level of vitamin D and prevalence of vitamin D deficiency among children with asthma in Asia and Africa: a systematic review and meta-analysis

BACKGROUND

Several studies on the serum level of vitamin D and the percentage of vitamin D deficiency in children with asthma have been conducted in Asia and Africa, but the results have been inconsistent and inconclusive, requiring a systematic review and meta-analysis to assess the strength of the evidence.

OBJECTIVE

The objective of this review is to synthesize evidence on serum levels of vitamin D and the percentage of vitamin D deficiency among children with asthma in Asia and Africa.

METHODS

To identify relevant articles, a comprehensive search was conducted across various databases and repositories such as PubMed, Google Scholar, Hinary, Web of Science, ResearchGate, as well as gray literature sources. The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines were followed during the retrieval process. Data extraction was performed following a standardized format based on the JBI (Joanna Briggs Institute) data extraction guidelines. Microsoft Excel was utilized for data extraction, and subsequently, the data was exported to STATA 17 for further analysis. To assess the heterogeneity among the included studies, Cochrane Q-statistics and the I2 tests were employed. Publication bias was assessed using the Egger test and funnel plot.

RESULT

This meta-analysis investigated 33 articles encompassing a total of 3432 children diagnosed with asthma. The findings demonstrated that in low- or middle-income countries across Africa and Asia, children with asthma had an average serum vitamin D level of 21.9 ng/ml (95% confidence interval [CI]: 18.0-25.9 ng/ml), with 53.7% (95% CI: 40.5-66.9) experiencing vitamin D deficiency. Additionally, when considering the continent, children with asthma in Asia had an average serum vitamin D level of 18.5 ng/ml (95% CI: 13.8-23.3), while those in Africa had a level of 28.7 ng/ml (95% CI: 22.7-34.8). The analysis further explored different sub-group analyses. Depending on the study design, case-control studies yielded an average serum vitamin D level of 20.3 ng/ml (95% CI: 18.2-22.4), whereas cross-sectional studies resulted in 23.8 ng/ml (95% CI: 17.5-30.1). Based on publication year, studies published on or before 2015 had an average serum level of 21.0 ng/ml (95% CI: 18.0-24.0), while those published after 2015 had a level of 22.4 ng/ml (95% CI: 17.2-27.7). Moreover, when considering sample size, studies with 100 participants or less had an average serum level of 21.7 ng/ml (95% CI: 17.3-26.1), while studies with more than 100 participants had a level of 22.1 ng/ml (95% CI: 18.6-25.6).

CONCLUSION

Children with asthma in Asia and Africa were found to have low serum levels of vitamin D and a high percentage of vitamin D deficiency. This highlights the importance of early detection and monitoring of vitamin D levels in these children to prevent potential complications associated with vitamin D deficiency. Taking proactive measures to address and manage vitamin D deficiency is crucial for the well-being of children with asthma in these regions.

Vitamin D [Serum 25(OH) cholecalciferol] Insufficiency is Associated With Childhood Asthma: Recent Case-Control Findings From Bangladesh

Objectives. To evaluate the interaction between childhood asthma and S. 25(OH) cholecalciferol among Bangladeshi children. Methods. This case control study was conducted in child asthma clinic, Bangladesh Shishu Hospital Institute during March-August 2021. Comparison was made between clinically-diagnosed (following GINA guideline) asthmatic children (2-12 years-old) (cases = 87) and age and sex-matched children having no respiratory illness (controls = 90) using SPSS' (Statistical Package for Social Science, V.23.0 Windows) software. Results. Serum 25(OH) cholecalciferol was found to be significantly lower among the cases than the controls (P < .01). The cases had 3.4 times higher likelihood of having low vitamin D (combined deficient + insufficient) than the controls (P < .01). Conclusions. The results of the study demonstrate an association of Serum 25 (OH) cholecalciferol with asthma which underscores the importance of potential future trial to evaluate the efficacy of Vitamin-D supplementation for understanding the outcomes of asthmatic Bangladeshi children.

Correlation of vitamin D receptor genotypes, specific IgE levels and other variables with asthma control in children

INTRODUCTION

Asthma is a common condition affecting millions of children globally. The main goal of this study is to assess factors related to asthma management, particularly atopy level and the impact of genetic variants of the vitamin D receptor (VDR) gene.

METHODS

Asthmatic children were enrolled in an outpatient respiratory clinic. Information on patients' medication adherence, medical and medication factors, and sociodemographic were gathered. Spirometry FEV1% and FVC% measurements, and the asthma control test were used to evaluate the severity of asthma, and genotyping of the VDR gene and radioallergosorbent test (RAST) were conducted. Regression analyses were conducted to evaluate variables associated with asthma control and spirometry measures.

RESULTS

A total of 313 participants (67.4% males) were recruited in the current study. The mean age was 9.37 (±3.45) years. The mean score for adherence was 4.26 (±2.52), and only 46% of the participants had controlled asthma. Forward conditional stepwise binary regression showed that low and moderate Inhaled corticosteroids (ICS) dose (OR= 0.42 (95% CI 0.20-0.90), p = 0.026; OR = 0.371 (95% CI 0.2-0.72), p = 0.003, respectively) decreased the odds of being in the controlled asthma group, while higher inhaler score (OR = 2.75 (95% CI 2.17-3.49, p < 0.001)) increased the odds of being in the controlled asthma group. However, results found no association between VDR genotype and asthma control, spirometry values or hospitalization due to asthma.

CONCLUSIONS

The results indicated that many of the asthma patients had poorly controlled asthma. Factors that were associated with poor asthma control included poor inhaler technique.

Association of polymorphisms of vitamin D gene in children with asthma and allergic rhinitis - Hospital based study

Vitamin D gene polymorphisms are known to be associated with asthma and allergic rhinitis in children. However, the genetic association of the same in South Indian children with above condition is still unknown. The present study was designed with the objective to analyze the association of polymorphisms of vitamin D receptor gene (VDR) (rs797532, rs154410, rs2258470, rs731236) and transport gene of vitamin D (rs7041) in children with asthma and allergic rhinitis in South India. Children (1-18years) presenting with symptoms suggestive of asthma and allergic rhinitis to hospital based outpatient department, in Vellore, South India were recruited as cases and children presenting with minor illness without respiratory complaints were enrolled as controls during January 2018 to September 2021. Polymorphisms were genotyped using tetra-arms PCR. Significant increase in levels of absolute eosinophil counts and serum IgE levels with decrease in vitamin D levels was seen among the cases. Significant association between levels of vitamin D and serum IgE was also observed. Analysis of polymorphisms showed that, in comparison to homozygous major allele the odds of having heterozygous (OR0.55 (0.3, 0.99) and homozygous minor form (OR0.52 (0.28, 0.97) of rs7975232, homozygous minor (OR 0.51 (0.34, 0.76)) and alternate allele (OR 0.7 (0.53, 0.93)) of rs154410 and homozygous minor form (OR 0.57 (0.37, 0.88) of rs731236 was significantly lesser among the cases. Genotypic model of rs154410 (p0.023) and allele form of rs7041 (p 0.041) were significantly associated with vitamin D levels however no association of gene blocks with cases was seen in haplotype analysis. There was an apparent gene pool difference noted in comparative analysis between Indian studies. The study is the first in south India to analyze levels of serum IgE, Vitamin D levels, association of VDR polymorphisms, and rs7041 in children with asthma.

Vitamin D and Respiratory Diseases : Based on 11th Dr. I. C. Verma Excellence in Research Award for Young Pediatricians Delivered as Oration on 15th Oct. 2023

The significance of Vitamin D has been appreciated beyond bone health and calcium metabolism. The importance of Vitamin D in respiratory health has been recognized due to its immunomodulatory and anti-microbial properties. The hypothesis is that Vitamin D could have a significant role in the pathogenesis of respiratory diseases and may represent a novel preventive and therapeutic strategy. Furthermore, enumerable observational studies established the association of Vitamin D deficiency with respiratory diseases such as asthma, bronchiolitis, pneumonia, tuberculosis, etc. However, experimental studies have not shown the encouraging results. This brief review will summarize and discuss the synthesis and metabolism of Vitamin D, the prevalence of Vitamin D deficiency in children, its role in the pathogenesis of various childhood respiratory diseases, and an overview of the therapeutic trials assessing the role of Vitamin D supplementation in childhood respiratory diseases.

Mini-Review on Vitamin D in Pediatric Population and its Role in Respiratory and Atopic Disorders

In recent years, our comprehension of the function of vitamin D has significantly evolved. The ubiquitous presence of the vitamin D receptor (Vitamin D Receptor- VDR) in the body has led to its redefinition from a steroidal hormone primarily involved in skeletal functions to a hormone with pleiotropic effects, exerting its influence on the circulatory, nervous, and immune systems. This has prompted investigations into its potential use in preventing and treating chronic metabolic disorders, cardiovascular diseases, infections, and allergic and autoimmune diseases. This comprehensive review explores the various aspects of vitamin D, including its sources, synthesis, functions, and its impact on different physiological systems. It delves into the epidemiology of vitamin D deficiency, highlighting its occurrence among various age demographics and geographic regions. The impact of vitamin D on the immune system is also explored, elucidating its immunomodulatory and anti-inflammatory properties, particularly in the context of respiratory infections. The review discusses emerging evidence concerning the potential advantages of vitamin D in respiratory diseases, pediatric asthma and atopic dermatitis. It also addresses vitamin D supplementation recommendations for various pediatric populations, including term and preterm infants. The growing concern regarding the global health impacts of insufficient vitamin D levels necessitates further research to bridge gaps in knowledge, particularly in enhancing screening, prevention, and approaches to address vitamin D deficiency from birth onwards. In summary, this comprehensive overview underscores the vital role of vitamin D, highlighting the significance of understanding its multifaceted functions and the need for tailored supplementation strategies, especially in vulnerable populations.

Assessment of the Relation Between Asthma Severity and Serum Vitamin D Levels: A Cross-Sectional Study

Introduction Vitamin D3's importance for bone health in children and its potential role beyond musculocutaneous health is an ongoing area of research. This study assesses vitamin D3 deficiency prevalence in asthmatic children and its correlation with asthma cases and healthy controls.  Methods This cross-sectional study was conducted in a tertiary care hospital in Punjab, India among children between 5 and 15 years of age. Fifty children diagnosed with "bronchial asthma" who were under follow-up in the asthma clinic in outpatient and inpatient patients were enrolled as cases. Age-matched 50 healthy controls who presented for routine check-ups were enrolled in the control group. Demographic details were noted and clinical examination was done in all the cases. 25-(OH) vitamin D levels were estimated and compared in all cases and controls. The study also analyzed the relationship between 25-(OH) vitamin D levels with asthma control and severity. Results The study showed that serum vitamin D3 level was significantly decreased in asthmatic children (24.62 ± 14.95 ng/ml) as compared with the healthy control group (32.08 ± 12.22 ng/ml). Also, serum vitamin D3 level was significantly decreased in children with uncontrolled asthma (12.06 ± 4.68 ng/ml) as compared to children with well-controlled asthma (44.82 ± 10.48 ng/ml).  Conclusion The findings showed that low serum levels were observed more in asthmatic children as compared to healthy children. A correlation was also found between vitamin D3 levels and asthma severity, its control, and the number of acute exacerbations in the last year.

Macronutrient and Micronutrient Intake in Children with Lung Disease

This review article aims to summarize the literature findings regarding the role of micronutrients in children with lung disease. The nutritional and respiratory statuses of critically ill children are interrelated, and malnutrition is commonly associated with respiratory failure. The most recent nutrition support guidelines for critically ill children have recommended an adequate macronutrient intake in the first week of admission due to its association with good outcomes. In children with lung disease, it is important not to exceed the proportion of carbohydrates in the diet to avoid increased carbon dioxide production and increased work of breathing, which potentially could delay the weaning of the ventilator. Indirect calorimetry can guide the process of estimating adequate caloric intake and adjusting the proportion of carbohydrates in the diet based on the results of the respiratory quotient. Micronutrients, including vitamins, trace elements, and others, have been shown to play a role in the structure and function of the immune system, antioxidant properties, and the production of antimicrobial proteins supporting the defense mechanisms against infections. Sufficient levels of micronutrients and adequate supplementation have been associated with better outcomes in children with lung diseases, including pneumonia, cystic fibrosis, asthma, bronchiolitis, and acute respiratory failure.

The Association between Vitamin D, Interleukin-4, and Interleukin-10 Levels and CD23+ Expression with Bronchial Asthma in Stunted Children

Children with stunted growth have an increased risk of wheezing, and studies have shown that low levels of vitamin D and interleukin (IL)-10, along with increased IL-4 levels and CD23+ expression, are present in stunted and asthmatic children. To date, it is not known whether these factors are related to the incidence of asthma in stunted children. This case-control study investigated the association between vitamin D, IL-4, and IL-10 levels and CD23+ expression with bronchial asthma in stunted children. The study included 99 children aged 24-59 months, i.e., 37 stunted-sthmatic children (cases), 38 stunted children without asthma, and 24 non-stunted children with asthma. All children were tested for their 25(OH)D levels using chemiluminescent immunoassay (CLIA), IL-4 and IL-10 levels were measured through enzyme-linked immunosorbent assay (ELISA) testing, and CD23+ expression was measured through flow cytometry bead testing. The data were analyzed using chi-squared, Kruskal-Wallis, and Mann-Whitney tests. The results showed that stunted asthmatic children had a higher incidence of atopic family members than those without asthma. Additionally, stunted asthmatic children had a higher prevalence of vitamin D deficiency (48.6%) than the control group (44.7% and 20.8%). Furthermore, stunted asthmatic children had significantly lower levels of 25(OH)D [20.55 (16.18-25.55), p = 0.042] and higher levels of IL-4 [1.41 (0.95-2.40), p = 0.038], although there were no significant differences in IL-10 levels and CD23+ expression. The study concluded that low vitamin D and high IL-4 levels are associated with bronchial asthma in stunted children, while IL-10 and CD23+ do not show a significant association.

A Scoping Review of Vitamin D for Nonskeletal Health: A Framework for Evidence-based Clinical Practice

BACKGROUND

Low serum 25-hydroxy-vitamin D [25(OH)D] levels are prevalent worldwide. Although the benefits of vitamin D supplementation have focused on skeletal disorders (eg, rickets, osteomalacia, osteoporosis), emerging evidence for nonskeletal health merits further discussion.

PURPOSE

The purpose of this review was to critically examine the vitamin D supplementation literature pertaining to nonskeletal health to help guide clinicians.

METHODS

A scoping review that included observational studies and randomized clinical trials (RCTs) was performed. Evidence from meta-analyses and individual RCTs are discussed, and controversies and future directions are considered.

FINDINGS

25(OH)D deficiency is a ubiquitous condition associated with multiple nonskeletal diseases, including cardiometabolic (heart disease, diabetes, and kidney disease), immune (HIV/AIDS and cancer), lung (from traditional chronic disorders to coronavirus disease 2019), and gut diseases. Vitamin D deficiency also affects health across the life span (children, pregnant, and elderly), mental illness, and reproduction in both men and women. In contrast, vitamin D supplementation does not necessarily improve major medical outcomes, even when low 25(OH)D levels are treated. Screening for 25(OH)D status remains an important practice, primarily for high-risk patients (eg, elderly, women with osteoporosis, people with low exposure to sunlight). It is reasonable to supplement with vitamin D to treat 25(OH)D deficiency, such that if beneficial nonskeletal health occurs, this may be considered as a coadjutant instead of the central tenet of the disease. Furthermore, optimizing dosing regimens is an important clinical consideration.

IMPLICATIONS

Although 25(OH)D deficiency is prevalent in nonskeletal diseases, there is no uniform evidence that vitamin D supplementation improves major medical outcomes, even when low 25(OH)D levels are corrected. Findings from RCTs warrant caution due to possible selection bias. Overall, vitamin D supplementation must be guided by circulating levels as a reasonable medical practice to correct 25(OH)D deficiency.

Oral vitamin D supplementation and body weight in children and adolescents: a systematic review and meta-analysis of randomized controlled trials

This study was designed to ascertain whether oral vitamin D supplementation (oral supplementation and fortified foods) is associated with changes in body weight measures in children and adolescents, using a systematic review and meta-analysis of randomized controlled trials (RCTs). PubMed, Scopus, Cochrane, and Web of Science databases were searched from inception to October 28, 2022. The mean difference and corresponding 95% confidence interval (CI) of interested outcomes were pooled using a random-effects model. Twenty-one RCTs were included in the meta-analysis, and the results showed a significant decrease in body mass index (BMI) following vitamin D supplementation in children and adolescents (n = 9 studies, 1029 participants; weighted mean difference: - 0.43 kg/m², 95% CI: - 0.79, - 0.08; P = 0.02; I² = 58.5%). Overall, oral vitamin D supplementation had no significant effect on body weight and other anthropometric indices, including fat mass, lean mass, waist circumference, BMI Z-score, and height. Although results of body weight changed to significant after sensitivity analysis (WMD = 0.39 kg, 95% CI = 0.01, 0.78; P = 0.04; I² = 0%, P-heterogeneity = 0.71), we also found significant weight gain in healthy pediatric population, and when the dose of vitamin D supplementation was up to 600 IU/day, the certainty of evidence was very low for weight, moderate for height and BMI, and low for the remaining outcomes.

CONCLUSION

Our results suggest that vitamin D supplementation may lead to a statistically significant weight gain in children and adolescents, while BMI was reduced. Although no significant change was observed in height, it seems vitamin D supplementation may elicit these changes by increasing skeletal growth; however, this remains to be verified. Further high-quality RCTs, with longer duration and larger sample sizes, are needed to yield more certain evidence in this regard.

WHAT IS KNOWN

• Available evidence indicates an inverse association between body weight/fat mass and vitamin D status in children and adolescents; however, findings regarding the effect of vitamin D supplementation on anthropometric measurements in children are controversial.

WHAT IS NEW

• Our results showed a significant decrease in BMI following vitamin D supplementation in children. • A significant weight gain also was observed after sensitivity analysis, and in healthy pediatric population, and when the dose of vitamin D supplementation was up to 600 IU/day.

Association between serum Vitamin D levels and asthma severity and control in children and adolescents

OBJECTIVE

To assess the association of serum Vitamin D (vitD) levels with asthma control and severity in children and adolescents in different seasons of the year.

METHOD

Longitudinal, prospective study with 7- to 17-year-old children and adolescents diagnosed with asthma. All participants underwent two assessments conducted in opposite seasons of the year which included a clinical assessment, a questionnaire for classification of asthma control (Asthma Control Test), spirometry, and blood collection to measure serum vitD levels.

RESULTS

In total, 141 individuals with asthma were evaluated. The mean vitD was lower in females (p = 0.006) and sunlight exposure appears not to be an influencing factor for vitD levels. We found no differences in mean vitD of patients with controlled and uncontrolled asthma (p = 0.703; p = 0.956). However, the severe asthma group had lower mean Vitamin D than the mild/moderate asthma group for both assessments (p = 0.013; p = 0.032). In the first assessment, the group with vitD insufficiency had a higher prevalence of severe asthma (p = 0.015). Vitamin D was positively correlated with FEV₁ in both assessments (p = 0.008; p = 0.006) and with FEF_25-75% in the first assessment (p = 0.038).

CONCLUSION

In a tropical climate zone, there is no evidence of association between seasonality and serum vitD levels or between serum vitD levels and asthma control in children and adolescents. However, vitD and lung function were positively correlated and the group with vitD insufficiency had a higher prevalence of severe asthma.

Does BMI Modify the Association between Vitamin D and Pulmonary Function in Children of the Mild Asthma Phenotype?

Vitamin D deficiency and obesity are global health problems that are associated with increased asthma risk in children. The purpose of this study was to investigate whether BMI modifies pulmonary function across vitamin D tertiles in pediatric asthma patients of the mild asthma phenotype. This cross-sectional study conducted from November 2016-September 2017 compared lung function variability as assessed by spirometry and nitric oxide in exhaled breath (FeNO) among 35 normal-weight and 26 overweight/obese Greek schoolchildren (5-12 years old) with mild asthma. Serum 25 (OH)D levels ≥ 30 ng/mL were defined as 'sufficient', 20-30 ng/mL 'insufficient', and <20 ng/mL 'deficient'. Stratification by BMI category, linear regression showed positive associations between D, % FVC (β = 0.49, 95%CI: 0.05, 0.94), and % FEV₁ (β = 0.48, 95%CI: -0.01, 0.95) in the normal-weight only, adjusted for age, sex, regular exercise, and medication. FEV₁ was 10% higher in the normal-weight D-sufficient group compared to those D-deficient (β = 10.43, 95%CI: 0.54, 20.32). No associations were observed for the overweight/obese group or FeNO. In conclusion, BMI modified associations of vitamin D on airway mechanics in children of the mild asthma phenotype. Serum 25 (OH)D concentrations ≥ 30 ng/mL were associated with higher ventilation in central airways of normal-weight asthmatic children.

Micronutrients and the Risk of Allergic Diseases in School Children

Microelements and vitamins are believed to have immunomodulatory effects. The aim of the study was to establish the role of antioxidants (vitamins A, E, D) and microelements such as copper (Cu), selenium (Se), and zinc (Zn) levels in allergic diseases in schoolchildren. The study uses a cohort of 80 children (40 with and 40 without allergy/asthma diagnosis) aged 9 to 12 years recruited for the Polish Mother and Child Cohort Study. At nine to twelve years old, the children were tested for microelement and vitamin content and health status (including skin-prick test and spirometry, urine cotinine level). Demographic data were collected from mothers by an allergist. The risk of asthma occurrence was found to be significantly related to the levels of Cu and Zn. The level of Cu was also particularly closely associated with allergic rhinitis and was indicated as a significant predictor of food allergy. The levels of Cu and Zn, and poor nutritional status in general, can influence the immune system and may be considered risk factors for developing asthma, allergic rhinitis and food allergy.

Low socioeconomic status predicts vitamin D status in a cross-section of Irish children

Vitamin D is essential for bone and muscle health with adequate status in childhood crucial for normal skeletal development. We aimed to investigate vitamin D status in a convenience sample (n = 1226) of Irish children (aged 1-17 years) who had serum 25-hydroxyvitamin D (25(OH)D) tested by request of their GP at a Dublin Hospital between 2014 and 2020. We examined predictors including age, sex, season and socioeconomic status (SES). Vitamin D deficiency (<30 nmol/l) was prevalent affecting 23 % and was more common in disadvantaged areas (34 %) and in those aged >12 v. ≤12 years (24 % v. 16 %, P = 0⋅033). The greatest predictor was SES (disadvantaged v. affluent, OR 2⋅18, CI 1⋅34, 3⋅53, P = 0⋅002), followed by female sex (OR 1⋅57, CI 1⋅15, 2⋅14, P = 0⋅005) and winter season (October to February, OR 1⋅40, CI 1⋅07, 1⋅84, P = 0⋅015). A quarter of our sample of children were deficient, rising to one-third in those in disadvantaged areas. Females and those aged over 12 years had a higher prevalence of deficiency. Public health strategies to improve vitamin D status in Irish children, including systematic food fortification may need to be considered to address this issue.

Vitamin D and Multiple Health Outcomes: An Umbrella Review of Observational Studies, Randomized Controlled Trials, and Mendelian Randomization Studies

Observational studies, randomized controlled trials (RCTs), and Mendelian randomization (MR) studies have yielded inconsistent results on the associations of vitamin D concentrations with multiple health outcomes. In the present umbrella review we aimed to evaluate the effects of low vitamin D concentrations and vitamin D supplementation on multiple health outcomes. We summarized current evidence obtained from meta-analyses of observational studies that examined associations between vitamin D concentrations and multiple health outcomes, meta-analyses of RCTs that investigated the effect of vitamin D supplementation on multiple health outcomes, and MR studies that explored the causal associations of vitamin D concentrations with various diseases (international prospective register of systematic reviews PROSPERO registration number CRD42018091434). A total of 296 meta-analyses of observational studies comprising 111 unique outcomes, 139 meta-analyses of RCTs comprising 46 unique outcomes, and 73 MR studies comprising 43 unique outcomes were included in the present umbrella review. Twenty-eight disease outcomes were identified by both meta-analyses of observational studies and MR studies. Seventeen of these reported disease outcomes had consistent results, demonstrating that lower concentrations of vitamin D were associated with a higher risk for all-cause mortality, Alzheimer's disease, hypertension, schizophrenia, and type 2 diabetes. The combinations of consistent evidence obtained by meta-analyses of observational studies and MR studies together with meta-analyses of RCTs showed that vitamin D supplementation was associated with a decreased risk for all-cause mortality but not associated with the risk for Alzheimer's disease, hypertension, schizophrenia, or type 2 diabetes. The results indicated that vitamin D supplementation is a promising strategy with long-term preventive effects on multiple chronic diseases and thus has the potential to decrease all-cause mortality. However, the current vitamin D supplementation strategy might not be an efficient intervention approach for these diseases, suggesting that new strategies are highly needed to improve the intervention outcomes.

Vitamin D supplementation during pregnancy to prevent vitamin D deficiency in newborns: a systematic review and meta-analysis

Abstract Objectives: to assess the effects of vitamin D supplementation during pregnancy on the outcomes of vitamin D concentration in newborns, length at birth, overall health (Apgar), birth weight and maternal vitamin D concentration after childbirth. Methods: this research was conducted in the electronic databases of MEDLINE, LILACS, EMBASE and Cochrane Library until December 2020, using the terms “vitamin D”, “pregnancy”, “vitamin D deficiency”, “infant”, “newborn” and their synonyms. Randomized controlled trials were searched by evaluating the effects of maternal vitamin D supplementation in neonates. The data was analyzed on RevMan 5.4 software and the quality of evidence on GRADE. Results: the newborn’s overall health condition was presented as Apgar, with a mean difference (MD) of 0.15 (CI95%=0.06-0.25; p=0.002; I2=0%, two studies, 648 participants, moderate quality evidence) at the first minute and 0.11 (CI95%=0.04-0.17; p=0.001; I2=0%, two studies, 648 participants, moderate quality evidence) at the fifth minute. Significant effects were also presented at the length at birth considering any supplemented dose (MD=0.19; CI95%=0.08-0.30; p=0.0010; I2=0%, 1452 participants, low quality evidence) and birth weight in doses higher than 4000IU/day (MD=257.05 (CI95%=137.81-376.29; p<0.0001; I2=14%, 176 participants, moderate quality evidence). Conclusion: vitamin D supplementation during pregnancy improves serum 25 (OH) D concentration and suggests positive effects on overall health condition, length at birth and birth weight. PROSPERO CRD42017073292.

Vitamin D supplementation in childhood asthma: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

There is conflicting evidence for vitamin D supplementation in childhood asthma. We aimed to systematically synthesise the evidence on the efficacy and safety of vitamin D supplementation in childhood asthma.

METHODS

We searched electronic databases (Medline, Embase and Web of Science) and a register (CENTRAL) for randomised controlled trials (RCTs) published until 30 September 2021. RCTs enrolling asthmatic children (1-18 years old) and comparing vitamin D against placebo/routine care were included if they met at least one of the endpoints of interest (asthma attacks, emergency visits or hospitalisation). We used the Risk of Bias 2 tool for risk of bias assessment. Random-effects meta-analysis with RevMan 5.3 software was performed. The Grading of Recommendations Assessment, Development and Evaluation approach was used to assess the level of certainty of the evidence.

RESULTS

18 RCTs (1579 participants) were included. The pooled meta-analysis did not find a significant effect of vitamin D supplementation on asthma attacks requiring rescue systemic corticosteroids (six studies with 445 participants; risk ratio (RR) 1.13, 95% CI 0.86-1.48; I2=0%) (moderate-certainty evidence). In addition, there was no significant difference in the proportion of children with asthma attacks of any severity (11 trials with 1132 participants; RR 0.84, 95% CI 0.65-1.09; I2=58%) (very low-certainty evidence). Vitamin D does not reduce the need for emergency visits (three studies with 361 participants; RR 0.97, 95% CI 0.89-1.07; I2=0%) and hospitalisation (RR: 1.38, 95% CI 0.52-3.66; I2=0%) (low-certainty evidence).

CONCLUSION

Very low- to moderate-certainty evidence suggests that vitamin D supplementation might not have any protective effect in childhood asthma.

The effect of vitamin D, magnesium and zinc supplements on interferon signaling pathways and their relationship to control SARS-CoV-2 infection

The concern of today's communities is to find a way to prevent or treat COVID-19 and reduce its symptoms in the patients. However, the genetic mutations and more resistant strains of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerge; the designed vaccines and adjuvant therapies would potentially control the symptoms and severity of COVID-19. The most important complication of this viral infection is acute respiratory distress syndrome, which occurs due to the infiltration of leukocytes into the alveoli and the raised cytokine storm. Interferons, as a cytokine family in the host, play an important role in the immune-related antiviral defense and have been considered in the treatment protocols of COVID-19. In addition, it has been indicated that some nutrients, including vitamin D, magnesium and zinc are essential in the modulation of the immune system and interferon (IFN) signaling pathway. Several recent studies have investigated the treatment effect of vitamin D on COVID-19 and reported the association between optimal levels of this vitamin and reduced disease risk. In the present study, the synergistic action of vitamin D, magnesium and zinc in IFN signaling is discussed as a treatment option for COVID-19 involvement.

Vitamin D receptor gene polymorphisms in atopy

Background

The occurrence of allergic conditions, for example allergic asthma, rhinitis, and atopic dermatitis, is rising worldwide. These allergic conditions are associated with poor life quality. Vitamin D is proposed to be linked with increased risk and severe forms of allergic diseases.

Aims

This review article aimed to evaluate the vitamin D level role and polymorphisms of vitamin D receptor gene (VDR) in atopy.

Methods & Materials

We analyzed publications that were focusing on levels of vitamin D and/or polymorphism analysis of vitamin D receptor gene in allergic asthma, rhinitis, and atopic dermatitis patients.

Results

We noticed that levels of vitamin D are extensively studied in atopy by many research groups, however, polymorphisms of vitamin D receptor gene and their link with levels of vitamin D lack comprehensive data. There is evidence that vitamin D may be associated with anti‐inflammatory effects in allergic diseases. Some of VDR polymorphisms also may play a role in pathogenesis of these diseases. However, the data from different studies are controversial.

Discussion

The results of different studies are usually inconsistent, most probably due to populational bias or differences in methodology. Even though, more evidence shows a positive impact of vitamin D on the risk and outcomes of allergic diseases, especially atopic dermatitis, and asthma.

Conclusions

There is controversial data about the level of vitamin D and its role in atopy; however, more evidence shows a positive impact on the risk and outcomes of allergic diseases.

Effect of age and body mass index on vitamin D level in children with asthma in Riyadh

Vitamin D deficiency prevalence in children has been rising. Low 25-hydroxyvitamin D3 (25(OH)D3) levels contribute to poor asthma control in children. This study assessed 25(OH)D3 levels in children with asthma from Riyadh with respect to anthropometrics, dietary, and lifestyle variables. Children with asthma (n, 60; 2–17 years) were assessed for serum 25-hydroxy vitamin D3 (25(OH)D3) level and body anthropometrics (weight, height, and body mass index [BMI]). Vitamin D dietary intake, sun exposure, and sociodemographic data were collected using a structured questionnaire. Thirty-one children (52%) had a 25(OH)D3 level < 50 nmol/L, 15 of whom (25%) had a level < 30 nmol/L. 25(OH)D3 level was significantly negatively correlated with age (P < 0.05), weight (P < 0.02), and height (P < 0.05). Children with a 25(OH)D3 level < 30 nmol/L had a significantly higher BMI than children with insufficient and sufficient vitamin D levels (P < 0.01). There was no significant effect of sex on 25(OH)D3 level. Higher 25(OH)D3 level was associated with a greater body area exposure to the sun. This study found that > 50% of the children with asthma had below sufficiency vitamin D levels. The vitamin D screening and supplementation of older and overweight children with asthma is recommended.

Vitamin-D supplementation as an adjunct to standard treatment of asthma in children: A randomized controlled trial (ViDASTA Trial)

OBJECTIVE

To determine the role of vitamin D supplementation as an adjunct to standard treatment in childhood asthma.

STUDY DESIGN

In this placebo-controlled, blinded, randomized controlled trial, we enrolled 60 children aged 6 to 11 years with moderate persistent asthma and randomly assigned them into intervention (2000 IU per day of vitamin D) and placebo groups (n = 30 each). The primary outcome was asthma control as assessed by the childhood asthma control test (C-ACT) scores at 12 weeks post-randomization. The secondary outcomes were improvement in the forced expiration in 1 s (FEV₁ ), fractional exhaled nitric oxide (FeNO), asthma exacerbations, use of systemic steroids, number of emergency visits, post-intervention vitamin D levels, and adverse outcomes. We analyzed by intention to treat.

RESULTS

There was no significant difference between the C-ACT score in the two groups (median [first-third quartile] scores were 25 [24-26] in both groups, p = 0.7). Also, there was no significant difference between the two groups in terms of the FEV₁ , FeNO, number of exacerbations, emergency visits, hospital admissions, and adverse outcomes. However, the post-intervention vitamin D levels (ng/ml) were significantly higher in the intervention group (35.5 vs. 18.8; p < 0.001). As compared to the baseline, both the groups showed better asthma control at 12 weeks post-intervention, irrespective of the type of intervention.

CONCLUSION

Vitamin-D supplementation as an adjunct to standard treatment does not improve asthma control in children.

Application of Metabolomics in Pediatric Asthma: Prediction, Diagnosis and Personalized Treatment

Asthma in children remains a significant public health challenge affecting 5–20% of children in Europe and is associated with increased morbidity and societal healthcare costs. The high variation in asthma incidence among countries may be attributed to differences in genetic susceptibility and environmental factors. This respiratory disorder is described as a heterogeneous syndrome of multiple clinical manifestations (phenotypes) with varying degrees of severity and airway hyper-responsiveness, which is based on patient symptoms, lung function and response to pharmacotherapy. However, an accurate diagnosis is often difficult due to diversities in clinical presentation. Therefore, identifying early diagnostic biomarkers and improving the monitoring of airway dysfunction and inflammatory through non-invasive methods are key goals in successful pediatric asthma management. Given that asthma is caused by the interaction between genes and environmental factors, an emerging approach, metabolomics—the systematic analysis of small molecules—can provide more insight into asthma pathophysiological mechanisms, enable the identification of early biomarkers and targeted personalized therapies, thus reducing disease burden and societal cost. The purpose of this review is to present evidence on the utility of metabolomics in pediatric asthma through the analysis of intermediate metabolites of biochemical pathways that involve carbohydrates, amino acids, lipids, organic acids and nucleotides and discuss their potential application in clinical practice. Also, current challenges on the integration of metabolomics in pediatric asthma management and needed next steps are critically discussed.

Association of vitamin D receptor gene polymorphisms in North Indian children with asthma: a case-control study

Asthma is a complex genetic disease. Vitamin D and vitamin D receptor (VDR) gene polymorphisms are involved in asthma pathogenesis. However, accurate inflammatory mechanisms and their role in VDR gene polymorphisms are unclear. The objective of this study was to investigate the association of VDR gene polymorphisms, ApaI, FokI, TaqI, and BsmI with asthma as compared to controls. Children (age 5-15 years) with a history of respiratory symptoms (wheeze, shortness of breath and chest tightness) were recruited as cases. Age matched children admitted with central nervous system disorders (encephalitis/seizures) without any respiratory complaints were recruited as controls after parental consent. Children with a clinical diagnosis of cystic fibrosis, congenital heart disease and whose parents did not consent for participation in the study were excluded. VDR gene polymorphisms were genotyped using PCR-RFLP method. One hundred and sixty asthmatics and one hundred controls were enrolled in this study. Mean age of the cases was 103.29±32.7 months and controls 94.24±30.52 months. Children with heterozygous (AC) genotype [OR=1.83, 95% CI=1.01-3.32, p=0.046] of ApaI polymorphism were found to be associated with the risk of asthma. Our findings suggest that ApaI polymorphism of VDR gene may contribute to asthma susceptibility among children.

Efficacy of vitamin D supplementation in asthmatic children with vitamin D deficiency: A randomized controlled trial (ESDAC trial)

BACKGROUND

Vitamin D supplementations for asthma control had shown inconsistent results. We aimed to study efficacy and safety of vitamin D supplementation in asthmatic children who were vitamin D deficient.

METHODS

This double-blind, randomized controlled trial enrolled asthmatic children of 4-12 years of age who had 25-hydroxyvitamin D [25(OH)D] levels <20 ng/mL. The participants were randomized to receive either vitamin D orally 1000 IU/d for 9 months or similar-looking placebo. The primary outcomes were the proportion of children having the Childhood Asthma Control Test (CACT) score of ≥20 at the end of the treatment and adverse effects.

RESULTS

The trial included 250 children (125 in each group) with a mean age of 8.1 ± 2.3 years and 180 boys. The baseline parameters were similar between the groups, including CACT score (21.7 ± 4.2 vs 21.9 ± 3.6, vitamin D vs placebo). At the end of the study, the proportion of asthmatic children who had CACT score ≥ 20 was similar between vitamin D and placebo group (93.6% vs 92.0%, P = .625). The number of exacerbations of asthma and side effect profile was also identical between the groups. 25(OH)D levels increased significantly in the vitamin D group (18.06 ± 7.11 vs 12.03 ± 5.98 ng/mL, P < .001). The results did not change when we did subgroup analysis for children with baseline CACT score < 20 and 25(OH)D levels at the end of the study ≥20 ng/mL.

CONCLUSION

Vitamin D supplementation in asthmatic children with vitamin D deficiency did not improve control of asthma.

Prenatal vitamin D supplementation and child respiratory health: A systematic review and meta-analysis of randomized controlled trials

Background

Systematic review and meta-analyses of observational studies on maternal vitamin D status and risk of respiratory allergic conditions indicated that mothers who had supplementation during pregnancy could decrease the risk of recurrent wheeze or asthma in their offspring.

Objectives

We conducted this meta-analysis of Randomized Controlled Trials with the primary intention of detecting the effect of prenatal vitamin D supplementation on the offspring's asthma. Secondary outcomes under respiratory health include eczema, lower respiratory tract infections, Immunoglobulin E positive test, upper respiratory tract infections, and allergic rhinitis.

Methods

A comprehensive search of PubMed, ScienceDirect, Google Scholar, and Cochrane Library databases was performed to retrieve randomized controlled trials. Risk Ratio with 95% confidence intervals was computed from dichotomous data using a random-effects model, with I² >50% representing notable heterogeneity.

Results

Six clinical trials met the inclusion criteria, involving a total of 2898 subjects (1461 experimental group and 1437 control group). There was non-significant inverse relationship between vitamin D intake during pregnancy and the occurrence of asthma in offspring (pooled RR = 0.89, 95% CI = 0.69-1.15, I ²  = 46% and Z-static = 0.90, P-value = 0.37). There is no significant difference in the risk of assessed childhood respiratory problems due to maternal supplementation of vitamin D during pregnancy.

Conclusion and implications

Currently, there is no fertile evidence to promote vitamin D supplementation in pregnancy for childhood respiratory health. Future clinical trials should emphasize early initiation of vitamin D supplementation, consider 6 weeks to 6 months postnatal critical window for vitamin D deficiency for offspring, lower risk dose of vitamin D, and identify different phenotypes of asthma and response to vitamin D supplementation.

Association of vitamin D gene polymorphisms in children with asthma - A systematic review

INTRODUCTION

The association of Vitamin D and children with asthma is known and there are several individual studies on Vitamin D polymorphisms. However, systematic reviews on all vitamin D associated gene polymorphisms have not been done in children with asthma.

OBJECTIVE

To investigate the association of Vitamin D associated gene polymorphisms and asthma in children (0-18 years) by systematic review and meta-analytic approach.

METHODS

Our search included 20 full text articles of which 15 were case control studies and 5 used family based linkage disequilibrium method. Total of 2491cases and 3682 controls were included in case control studies, with mean age of 9.58 years and 10.16 years respectively. Quantitative and qualitative analysis were done.

RESULTS

Quantitative analysis revealed significant association with protective effect of Apa1 polymorphism in allele (OR 0.81 (0.71,0.91) and homozygous major form (OR 0.83 (0.70,0.98) and Taq 1 minor allele in homozygous form (OR 0.73 (0.58,0.92) in children with asthma. However, the minor allele of Apa1(OR 1.21 (1.07,1.37), Bsm 1 in heterozygous (OR 1.35 (1.07,1.71) and homozygous minor form (OR 1.95 (1.59,2.39), major allele of Fok1(OR1.34 (1.17,1.52) and Taq1 (OR 1.22 (1.08,1.38) were found to be increasing the odds of asthma. Ethnic variations were noted in subgroup analysis. Qualitative analysis of the polymorphisms of the Vitamin D associated metabolic genes also showed significant associations.

CONCLUSION

Our review shows significant associations with VDR polymorphisms - Apa1, Bsm1, Fok 1, Taq 1, polymorphisms of Vitamin D metabolic genes - CYP27A1, CYP 2R1, CYP 24A1, GC and genes related to Vitamin D response element (VDRE) in children with asthma. Conducting large studies involving various ethnic regions will strengthen our knowledge on the association and aid in targeted interventions for control of asthma in children.

Sufficient vitamin D status positively modified ventilatory function in asthmatic children following a Mediterranean diet enriched with fatty fish intervention study

Asthma in children is the most prevalent allergic disease worldwide that has become a major public health priority. The objective of this study was to examine the relationship between baseline serum vitamin D status, spirometry, and fractional exhaled nitric oxide levels (FeNO) in 64 Greek children with 'mild asthma' aged 5 to 12 years (51.6% male) in a dietary intervention study. We hypothesized that baseline serum vitamin D levels modify the beneficial response of fatty fish intake on pulmonary function in asthmatic children following a Mediterranean diet. The intervention group consumed 2 fatty fish meals/week (≥150 g cooked filleted fish/meal) as part of the Mediterranean diet for six months, and the control group consumed their usual diet. Baseline serum 25(OH)D was determined using enzyme-linked immunoassay and defined as sufficient levels of 25(OH)D ≥25 ng/mL. Only 36% of children were graded as sufficient in 25(OH)D levels on entry into the study with a higher proportion of girls insufficient than boys (61% vs 39% respectively). Participants with sufficient levels of serum 25(OH)D at baseline, consuming the intervention diet increased FEV₁/FVC by 4.89 units (β = 4.89; 95%CI: 1.19-8.61; p = 0.013) and FEF_25-75% by 12.83 units (β = 12.83; 95%CI: 4.27-21.40; p = 0.006) compared to controls. No significant differences in pulmonary function or FeNO were observed for those with insufficient levels of 25(OH) D in the intervention or control groups. In conclusion, sufficient serum vitamin D levels enhanced ventilatory function in response to a dietary intervention in asthmatic children.

Association between vitamin D level and bronchopulmonary dysplasia: A systematic review and meta-analysis

Neonatal vitamin D deficiency is common and is associated with development of pulmonary disease in children and adults. While the role of vitamin D in normal lung development is well established, the association between vitamin D deficiency and bronchopulmonary dysplasia (BPD) remains unclear. The present meta-analysis was conducted to evaluate the relationship between vitamin D and BPD. We identified relevant studies (n = 8) using the PubMed, EMBASE, Cochrane Library, and KoreaMed databases and applied the Newcastle–Ottawa Scale to assess the methodological components of each study, and used I² statistic to evaluate heterogeneity. Comprehensive Meta-Analysis software version 3.3 was used for the statistical analysis. A total of 909 infants were included, of whom 251 (27.6%) were diagnosed with BPD. We found that both vitamin D deficiency at birth (four studies; OR 2.405; 95% CI 1.269 to 4.560; p = 0.007) and low levels of vitamin D at birth (four studies; standardized mean difference -1.463; 95% CI -2.900 to -0.027; p = 0.046) were associated with BPD. The compiled data suggest that antenatal vitamin D deficiency and low vitamin D levels are associated with neonatal BPD.

Appropriate and inappropriate vitamin supplementation in children

The vitamin status of a child depends on many factors and most of the clinical studies do not take into account the different access to adequate nutrition of children coming from different countries and the consequent major differences in micronutrients or vitamin deficits between low-income and high-income countries. Vitamin supplements are included in the general field of dietary supplements. There is a large amount of not always factual material concerning vitamin supplements, and this may sometimes create confusion in clinicians and patients. Inadequate information may lead to the risk of attributing beneficial properties leading to their over-use or misuse in the paediatric field. Vitamin supplementation is indicated in all those conditions in which a vitamin deficiency is found, either because of a reduced intake due to reduced availability of certain foods, restrictive diets or inadequate absorption. The lack of guidelines in these fields may lead paediatricians to an improper use of vitamins, both in terms of excessive use or inadequate use. This is due to the fact that vitamin supplementation is often intended as a therapy of support rather than an essential therapeutic tool able to modify disease prognosis. In fact, various vitamins and their derivatives have therapeutic potential in the prevention and treatment of many diseases, especially in emerging conditions of paediatric age such as type 2 diabetes and the metabolic syndrome. The aim of the present article is to analyse the state of the art and consider new perspectives on the role of vitamin supplements in children.

The risk of osteoporosis in patients with asthma

It is well-known that use of continuous systemic corticosteroids (SG) affects bone metabolism, bone mineral density (BMD), and ultimately increases the risk of osteoporosis. In patients with asthma, on the other hand, the effects of long-term high-dose inhaled corticosteroids (ICS) on BMD and risk of osteoporotic fractures is controversial. The reasons for this inconsistency could be explained by the fact that only few long-term studies investigating the effect of ICS in patients with asthma exist. The studies are characterized by different study designs and duration of ICS exposure, small study populations, and differences between the used ICS. The aim of this article is to unravel which factors, if any, that contribute to an increased risk of osteoporosis in patients with asthma and to summarize the evidence regarding adverse effects of ICS on bone metabolism, BMD and osteoporotic fractures in patients with asthma.

Role of Vitamin D in Preventing and Treating Selected Extraskeletal Diseases-An Umbrella Review

Evidence is accumulating that vitamin D may have beneficial effects on respiratory tract, autoimmune, neuro-degenerative, and mental diseases. The present umbrella review of systematic reviews (SRs) of cohort studies and randomised controlled trials (RCTs), plus single Mendelian randomisation studies aims to update current knowledge on the potential role of vitamin D in preventing and treating these extraskeletal diseases. Altogether, 73 SRs were identified. Observational data on primary prevention suggest an inverse association between vitamin D status and the risk of acute respiratory tract infections (ARI), dementia and cognitive decline, and depression, whereas studies regarding asthma, multiple sclerosis (MS), and type 1 diabetes mellitus (T1DM) are scarce. SRs of RCTs support observational data only for the risk of ARI. No respective RCTs are available for the prevention of chronic obstructive pulmonary disease (COPD), MS, and T1DM. SRs of RCTs indicate beneficial therapeutic effects in vitamin D-deficient patients with asthma and COPD, while effects on major depression and T1DM need to be further elucidated. Mendelian randomisation studies do not consistently support the results of SRs. Since several limitations of the included SRs and existing RCTs do not permit definitive conclusions regarding vitamin D and the selected diseases, further high-quality RCTs are warranted.

Targeting Vitamin D Deficiency to Limit Exacerbations in Respiratory Diseases: Utopia or Strategy With Potential?

Patients with respiratory diseases such as cystic fibrosis, chronic obstructive pulmonary disease, or asthma often experience an acute worsening of respiratory symptoms, termed exacerbations. Although the course of exacerbations is disease specific, they are mostly triggered by a respiratory infection. Exacerbations often require hospitalization and are an important cause of mortality. Treatments of exacerbations aim to minimize the negative impact and to prevent subsequent events. Despite many existing therapy options, many patients do not benefit from therapy and suffer from recurrent events. Vitamin D deficiency is a worldwide problem and is extremely prevalent in these patients. Vitamin D, known for its calcemic effects, also has immunomodulatory and anti-infectious actions and can therefore be a possible agent to treat or prevent exacerbations. This review will focus on vitamin D as a potential candidate to treat or prevent exacerbations in CF, COPD, and asthma.

Diet and Food Allergy as Risk Factors for Asthma in the Arabian Gulf Region: Current Evidence and Future Research Needs

Asthma is a chronic respiratory disease which is associated with higher levels of systemic inflammation. The causes of asthma remain poorly understood. Unhealthy diet and food allergy are potential risk factors for developing asthma. The prevalence of asthma in the Arabian Gulf region (AGR), and Kuwait, Saudi Arabia and Qatar in particular, is higher than in other Eastern Mediterranean countries. In the AGR, diets tend to be of low nutritional value due to high levels of total energy, cholesterol, sodium, added sugars and saturated fat, and low levels of fiber, fruit and vegetables. A few studies that include children and adults in the AGR have suggested a potential link between unhealthy diets/specific food allergens and increased risk of asthma, however, the association of food allergy with asthma is still a controversial issue. The aim of this commentary is to consider the evidence from the AGR regarding the effects of diet/food allergy on asthma risk that may be used to make recommendations for future research.

Meta-analysis of vitamin D and lung function in patients with asthma

Background

There is growing literature suggesting a link between vitamin D and asthma lung function, but the results from systematic reviews are conflicting. We conducted this meta-analysis to investigate the relation between serum vitamin D and lung function in asthma patients.

Methods

Major databases, including OVID, MEDLINE, Web of Science and PUBMED, were searched until 10th October 2018. All published observational studies related to vitamin D and asthma were extracted. All meta-analyses were performed using Review Manager 5.3.5.

Results

This quantitative synthesis found that asthma patients with low vitamin D levels had lower forced expiratory volume In 1 s (FEV1) (mean difference (MD) = − 0.1, 95% CI = − 0.11 to − 0.08,p < 0.01;I2 = 49%, p = 0.12) and FEV1% (MD = − 10.02, 95% CI = − 11 to − 9.04, p < 0.01; I2 = 0%, p = 0.82) than those with sufficient vitamin D levels. A positive relation was found between vitamin D and FEV1 (r = 0.12, 95% CI = 0.04 to 0.2, p = 0.003; I2 = 59%,p = 0.01), FEV1% (r = 0.19, 95% CI = 0.13 to 0.26, p < 0.001; I2 = 42%, p = 0.11), forced vital capacity (FVC) (r = 0.17, 95% CI = 0.00 to 0.34, p = 0.05; I2 = 60%, p = 0.04), FEV1/FVC (r = 0.4, 95% CI = 0.3 to 0.51, p < 0.001; I2 = 48%, p = 0.07), and the asthma control test (ACT) (r = 0.33, 95% CI = 0.2 to 0.47, p < 0.001; I2 = 0%, p = 0.7). Subgroup analysis indicated that the positive correlation between vitamin D and lung function remained significant in both children and adults.

Conclusions

Our meta-analysis suggested that serum vitamin D levels may be positively correlated with lung function in asthma patients. Future comprehensive studies are required to confirm these relations and to elucidate potential mechanisms.

Vitamin D for secondary prevention of acute wheeze attacks in preschool and school-age children

INTRODUCTION

Vitamin D is best known for its role in bone health; however, the discovery of the vitamin D receptor and the expression of the gene encoding the vitamin D 1α-hydroxylase (CYP27B1) enzyme in a wide variety of tissues including immune cells and respiratory epithelium has led to the discovery of potential roles for vitamin D in the prevention of acute wheeze.

METHODS

We review here the literature concerning the relationships between circulating 25-hydroxyvitamin D (25(OH)D) concentration and secondary prevention of acute wheeze attacks in preschool and school-age children.

RESULTS

Epidemiological data suggest that vitamin D insufficiency (25(OH)D <75 nmol/L) is highly prevalent in preschool and school-age children with wheeze. Preschool age children with a history of wheeze attacks and circulating 25(OH)D <75 nmol/L are at increased risk and frequency of future acute wheeze. However, no consistent association between low vitamin D status and risk of acute wheeze is reported in school-age children. Seven randomised controlled trials (RCTs) with relatively small sample sizes (30-430) and variable quality showed inconsistent results regarding the effect of oral vitamin D supplementation during childhood on the risk of asthma attacks, asthma symptom control, inhaled corticosteroid requirements, spirometry and unscheduled healthcare attendances for wheeze. A RCT showed that vitamin D supplementation had no effect on the frequency of unplanned healthcare attendances due to acute wheeze in 22 preschool children.

DISCUSSION

An evidence-based recommendation for the use of vitamin D as a preventive therapy for wheeze attacks cannot be made until results of further trials are available. The assessment of circulating 25(OH)D concentration and the optimisation of vitamin D status to prevent acute respiratory tract infections, and to maintain skeletal and general health in preschool and school-age children with acute wheeze is worthwhile in its own right, but whether this will reduce the risk of acute wheeze attacks is unclear.

Asthma in children with sickle cell disease

PURPOSE OF REVIEW

Asthma is common in children with sickle cell disease (SCD) and appears to be associated with increased morbidity. Providers caring for children with SCD have struggled with the question of whether asthma exists as a true comorbidity or whether certain aspects of the chronic inflammatory disease gives children with SCD an asthma-like phenotype.

RECENT FINDINGS

Clinical signs and symptoms seen in children with asthma in the general population, such as wheezing, airway hyperresponsiveness, atopy, elevated leukotrienes, and abnormal lung function are seen in children with SCD both with and without a diagnosis of asthma.

SUMMARY

Current evidence highlights that the presence of lung disease in children with SCD has significant implications irrespective of the underlying cause, including asthma. Further research should focus on well tolerated and effective interventions to prevent disease-related complications for children with pulmonary complications of SCD.

Prevalence of vitamin D deficiency and its relationship with factors associated with recurrent wheezing

Objective:

To determine the prevalence of vitamin D deficiency/insufficiency in children 0-18 years of age with recurrent wheezing and/or asthma residing in the microregion of Viçosa, Minas Gerais, Brazil, and treated at a referral center, and to determine its association with major risk factors for wheezing.

Methods:

A cross-sectional study was performed using a semi-structured questionnaire, which was administered by trained interviewers to the legal guardians of the study participants. Data were obtained regarding general characteristics of recurrent wheezing; general sociodemographic, environmental, and biologic factors; and atopy-related factors. The magnitude of the statistical association was assessed by calculating ORs and their corresponding 95% CIs by using multiple logistic regression.

Results:

We included 124 children in the study. The prevalence of vitamin D deficiency/insufficiency in the sample was 57.3%. Vitamin D deficiency/insufficiency was found to be associated with wheezing in the first year of life, personal history of atopic dermatitis, environmental pollution, and vitamin D supplementation until 2 years of age.

Conclusions:

The prevalence of vitamin D deficiency/insufficiency was high in our sample. Vitamin D concentrations were directly associated with vitamin D supplementation until 2 years of age and were inversely associated with wheezing events in the first year of life, personal history of atopic dermatitis, and environmental pollution.

Association of vitamin D receptor expression with inflammatory changes and prognosis of asthma

The expression level of vitamin D receptor in patients with asthma was investigated to study the association between vitamin D receptor and inflammatory changes in asthma. Thirty patients with bronchial asthma treated in the Tianjin Hospital of ITCWM Nankai Hospital were selected as the experimental group, while 30 healthy individuals were selected as the control group. The mRNA expression level of vitamin D receptor in blood was detected via reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The protein expression level of vitamin D receptor in blood was detected via western blot analysis and the levels of inflammatory factors were detected via enzyme-linked immune sorbent assay (ELISA). Correlations between the expression level of vitamin D and inflammatory factors were studied via Pearsons analysis. Finally, the prognoses of patients were recorded and analyzed. The results showed that the mRNA and protein expression levels of vitamin D receptor in the experimental group were significantly lower than those in control group (P<0.01). The content of 25-(OH) D₃ in serum in the experimental group was significantly lower than that in the control group (P<0.01). The contents of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in serum in the experimental group were obviously higher than those in the control group, but the contents of IL-10 and transforming growth factor-β (TGF-β) were obviously lower than those in the control group (P<0.01). Moreover, the correlation analysis revealed that IL-6 and TNF-α were negatively correlated with the expression of vitamin D receptor (P<0.05), whereas IL-10 and TGF-β were positively correlated with the expression of vitamin D receptor (P<0.05). In conclusion, the expression of vitamin D receptor is positively correlated with the levels of pro-inflammatory factors. Moreover, the vitamin D receptor affects the prognosis and recovery of lung function of patients with asthma.