Prenatal vitamin D status and respiratory and allergic outcomes in childhood: A meta-analysis of observational studies

Growing Up in Singapore with allergies - Lessons learnt from the GUSTO & S-PRESTO cohorts

Healthcare systems across the world face major challenges due to allergic diseases, known to affect people of all ages. In Singapore, two prominent cohort studies, Growing Up in Singapore Towards healthy Outcomes (GUSTO) and the Singapore PREconception Study of long-Term maternal and child Outcomes (S-PRESTO), have made notable advancements to our knowledge and understanding of allergic diseases. These cohorts, which comprised of healthy mother-infant dyads recruited from the healthy Singapore population, have shed light on the complex connections between factors influencing health in early life, preconception and pregnancy, on the pathogenesis of allergic disorders in offspring. GUSTO highlighted significant risk factors in antenatal and early life, such as maternal diet, health and lifestyle choices, as well as infant environmental influences, that contributed to the risk of allergic diseases in the Asian Singaporean population. It also identified differential patterns of allergic disease in comparison to other populations, particularly the role of the microbiome in predicting atopic outcomes. Meanwhile, S-PRESTO further explores the long-term maternal and child outcomes associated with preconception health. Findings seem to suggest that prevention of offspring allergic conditions can be achieved through optimizing maternal health and lifestyle choices before conception. Both studies underscore the significance of early life interventions, preconception health, and personalized approaches to effectively manage and prevent allergies. By leveraging the insights and promising findings from GUSTO and S-PRESTO, future work can drive development of preventative strategies and personalized interventions to reduce burden of allergic diseases in the Singapore population.

High-Dose Vitamin D Supplementation Significantly Affects the Placental Transcriptome

Vitamin D deficiency is a highly prevalent obstetrical concern associated with an increased risk of complications like pre-eclampsia, gestational diabetes, and growth retardation. Vitamin D status in pregnancy is also linked to long-term offspring health, e.g., the risk of obesity, metabolic disease, and neurodevelopmental problems. Despite the suspected role of vitamin D in placental diseases and fetal development, there is limited knowledge on the effect of vitamin D on placental function. Thus, we performed next-generation RNA sequencing, comparing the placental transcriptome from uncomplicated term pregnancies receiving the often-recommended dose of 10 µg vitamin D/day (n = 36) with pregnancies receiving 90 µg/day (n = 34) from late first trimester to delivery. Maternal vitamin D status in the first trimester was also considered. We found that signaling pathways related to cell adhesion, immune function, and neurodevelopment were affected, supporting that increased vitamin D supplementation benefits placental function in established pregnancies without severe vitamin D deficiency, also underlining the importance of vitamin D in brain development. Specific effects of the first trimester vitamin D status and offspring sex were also identified. Further studies are warranted, addressing the optimal vitamin status during pregnancy with a focus on organ-specific vitamin D needs in individual pregnancies.

Environmental Risk Factors, Protective Factors, and Biomarkers for Allergic Rhinitis: A Systematic Umbrella Review of the Evidence

Many potential environmental risk factors, protective factors, and biomarkers of AR have been published, but so far, the strength and consistency of their evidence are unclear. We conducted a comprehensive review of environmental risk, protective factors, and biomarkers for AR to establish the evidence hierarchy. We systematically searched Embase, PubMed, Cochrane Library, and Web of Science electronic database from inception to December 31, 2022. We calculated summary effect estimate (odds ratio (OR), relative risk (RR), hazard ratio (HR), and standardized mean difference (SMD)), 95% confidence interval, random effects p value, I2 statistic, 95% prediction interval, small study effects, and excess significance biases, and stratification of the level of evidence. Methodological quality was assessed by AMSTAR 2 (A Measurement Tool to Assess Systematic Reviews 2). We retrieved 4478 articles, of which 43 met the inclusion criteria. The 43 eligible articles identified 31 potential environmental risk factors (10,806,206 total population, two study not reported), 11 potential environmental protective factors (823,883 total population), and 34 potential biomarkers (158,716 total population) for meta-analyses. The credibility of evidence was convincing (class I) for tic disorders (OR = 2.89, 95% CI 2.11-3.95); and highly suggestive (class II) for early-life antibiotic use (OR = 3.73, 95% CI 3.06-4.55), exposure to indoor dampness (OR = 1.49, 95% CI 1.27-1.75), acetaminophen exposure (OR = 1.54, 95% CI 1.41-1.69), childhood acid suppressant use (OR = 1.40, 95% CI 1.23-1.59), exposure to indoor mold (OR = 1.66, 95% CI 1.26-2.18), coronavirus disease 2019 (OR = 0.11, 95% CI 0.06-0.22), and prolonged breastfeeding (OR = 0.72, 95% CI 0.65-0.79). This study is registered in PROSPERO (CRD42022384320).

Sex and obesity status modify the association between vitamin D and eczema among adolescents

BACKGROUND

Epidemiologic studies have reported inconsistent associations between vitamin D and eczema. This study sought to assess whether sex and obesity status could modify the association between vitamin D and eczema.

METHODS

A cross-sectional study enrolled 763 adolescents in Kuwait. 25-hydroxyvitamin D (25(OH)D) was measured in venous blood. Current eczema was defined according to clinical history and characteristic morphology and distribution.

RESULTS

In sex-stratified analysis, decreased 25(OH)D levels were associated with increased current eczema prevalence among males (adjusted odds ratio (aOR)tertile 1 vs. tertile 3: 2.14, 95% confidence intervals (CI): 1.07-4.56), but not among females (aORtertile 1 vs. tertile 3: 1.08, 95% CI: 0.71-1.66). Further stratification by obesity status showed that lower 25(OH)D levels were associated with increased current eczema prevalence among overweight/obese males (per 10-unit decrease in 25(OH)D levels: aOR: 1.70, 95% CI: 1.17-2.46). Such an association was weaker and statistically non-significant among overweight/obese females (per 10-unit decrease in 25(OH)D levels: aOR: 1.26, 95% CI: 0.93-1.70).

CONCLUSIONS

Sex and obesity status modified the association between vitamin D levels and eczema, with an inverse association observed among overweight/obese males, but not among overweight/obese females. These results suggest that preventive and clinical management strategies could vary by sex and obesity status.

IMPACT

The current study showed that sex and obesity modify the association between vitamin D and eczema among adolescents. An inverse association between vitamin D and eczema was observed among overweight/obese males, but this association was not as pronounced among overweight/obese females. Vitamin D was not associated with eczema among underweight/normal weight males and females. The identification of effect modification by sex and obesity status add to the current scientific knowledge and further highlight the complexity of the association between vitamin D and eczema. These results may promote a more individualized approach to the future prevention and clinical management of eczema.

Pregnancy, Breastfeeding, and Vitamin D

Exclusive breastfeeding is considered the ideal food in the first six months of life; however, paradoxically, vitamin D content in human breast milk is clearly low and insufficient to obtain the recommended intake of 400 IU daily. This article summarizes the extraordinary metabolism of vitamin D during pregnancy and its content in human breast milk. The prevalence of hypovitaminosis D in pregnant women and/or nursing mothers and its potential maternal-fetal consequences are analyzed. The current guidelines for vitamin D supplementation in pregnant women, nursing mothers, and infants to prevent hypovitaminosis D in breastfed infants are detailed. Low vitamin D content in human breast milk is probably related to active changes in human lifestyle habits (reduced sunlight exposure).

Association of Maternal Gestational Vitamin D Supplementation with Respiratory Health of Young Children

This study aimed to evaluate the association between maternal gestational Vitamin D3 supplementation and early respiratory health in offspring. This was a population-based record-linkage study which used data from the French National Health Database System. Maternal Vitamin D3 supplementation consisted of a single high oral dose of cholecalciferol, (100,000 IU) from the seventh month of pregnancy, according to national guidelines. In total, 125,756 term-born singleton children were included, of which 37% had respiratory illness defined as hospital admission due to respiratory causes or inhalation treatment up to 24 months of age. Infants prenatally exposed to maternal Vitamin D3 supplementation (n = 54,596) were more likely to have a longer gestational age (GA) at birth (GA 36-38 weeks, 22% vs. 20%, p < 0.001 in exposed vs. non-exposed infants, respectively). After adjusting for the main risk factors (maternal age, socioeconomic level, mode of delivery, obstetrical and neonatal pathology, birth weight appropriateness, sex, and birth season), the risk of RD was found to be 3% lower than their counterparts (aOR [IC 95%], 0.97 [0.95-0.99], p = 0.01). In conclusion, this study provides evidence for the association between maternal gestational Vitamin D3 supplementation and improved early respiratory outcomes in young children.

Is antenatal or early-life vitamin D associated with eczema or food allergy in childhood? A systematic review

OBJECTIVE

To summarise the associations between antenatal or early-life blood vitamin D and the development of eczema/food allergy in childhood.

DESIGN

A systematic review and meta-analyses were conducted to synthesize the published literature. Two reviewers independently performed the study selection and data extraction on Covidence. We assessed the risk of bias for observational studies by using the Newcastle-Ottawa Scale and the Cochrane Risk of Bias tool for clinical trials. The certainty of the evidence was assessed using Grading of Recommendations, Assessment, Development and Evaluations (GRADE).

DATA SOURCES

We systematically searched PubMed and Embase from inception and April 2022.

ELIGIBILITY CRITERIA

Human studies that investigated prospective associations between antenatal or early-life blood vitamin D levels, dietary intake or supplementation and childhood eczema/food allergy.

RESULTS

Forty-three articles including six randomised controlled trials (RCTs) were included. Four RCTs of vitamin D supplementation during pregnancy showed no evidence of an effect on the incidence of eczema (pooled odds ratio [OR] = 0.85; 0.67-1.08, I2  = 6.7%, n = 2074). Three RCTs reported null associations between supplementation in pregnancy/infancy and food allergy. From six cohort studies, increasing cord blood vitamin D levels were associated with reduced prevalence of eczema at/close to age one (OR per 10 nmol/L increase = 0.89; 0.84-0.94, I2  = 0%, 2025 participants). We found no evidence of an association between maternal antenatal or infant vitamin D level or dietary intake and the development of food allergy or eczema in offspring.

CONCLUSIONS

We found an association between higher vitamin D levels in cord blood and reduced risk of eczema in cohort studies. Further trials with maternal and infant supplementation are needed to confirm if vitamin D supplementation can effectively prevent eczema or food allergy in childhood.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, No. CRD42013005559.

Maternal exposure to urinary polycyclic aromatic hydrocarbons (PAH) in pregnancy and childhood asthma in a pooled multi-cohort study

BACKGROUND

Prenatal exposure to polycyclic aromatic hydrocarbons (PAH) may increase risk of pediatric asthma, but existing human studies are limited.

OBJECTIVES

We estimated associations between gestational PAHs and pediatric asthma in a diverse US sample and evaluated effect modification by child sex, maternal asthma, and prenatal vitamin D status.

METHODS

We pooled two prospective pregnancy cohorts in the ECHO PATHWAYS Consortium, CANDLE and TIDES, for an analytic sample of N = 1296 mother-child dyads. Mono-hydroxylated PAH metabolites (OH-PAHs) were measured in mid-pregnancy urine. Mothers completed the International Study on Allergies and Asthma in Childhood survey at child age 4-6 years. Poisson regression with robust standard errors was used to estimate relative risk of current wheeze, current asthma, ever asthma, and strict asthma associated with each metabolite, adjusted for potential confounders. We used interaction models to assess effect modification. We explored associations between OH-PAH mixtures and outcomes using logistic weighted quantile sum regression augmented by a permutation test to control Type 1 errors.

RESULTS

The sociodemographically diverse sample spanned five cities. Mean (SD) child age at assessment was 4.4 (0.4) years. While there was little evidence that either individual OH-PAHs or mixtures were associated with outcomes, we observed effect modification by child sex for most pairs of OH-PAHs and outcomes, with adverse associations specific to females. For example, a 2-fold increase in 2-hydroxy-phenanthrene was associated with current asthma in females but not males (RRfemale = 1.29 [95 % CI: 1.09, 1.52], RRmale = 0.95 [95 % CI: 0.79, 1.13]; pinteraction = 0.004). There was no consistent evidence of modification by vitamin D status or maternal asthma.

DISCUSSION

This analysis, the largest cohort study of gestational PAH exposure and childhood asthma to date, suggests adverse associations for females only. These preliminary findings are consistent with hypothesized endocrine disruption properties of PAHs, which may lead to sexually dimorphic effects.

Prevalence of Vitamin D Insufficiency/Deficiency and Their Role in Atopic Dermatitis Development and Course in Children

Various conclusive evidence on the role of vitamin D in the pathogenesis of atopic dermatitis (AD) has been obtained in recent decades. Many studies have shown that patients with AD have low concentration of 25(OH)D in blood associated with high concentration of allergen specific IgE (according to several reports). The analysis of low 25(OH)D concentration prevalence, association of vitamin D deficiency with AD severity and sensitization to allergens, and association of vitamin D disorders with risk of AD development is presented.

Fat-soluble vitamins: updated review of their role and orchestration in human nutrition throughout life cycle with sex differences

Age and Gender are vital determinants for the micronutrient demands of normal indviduals. Among these micronutrients are vitamins that are required in small amounts for optimum metabolism, homeostasis, and a healthy lifestyle, acting as coenzymes in several biochemical reactions. The majority of previous studies have examined such issues that relates to a specific vitamin or life stage, with the majority merely reporting the effect of either excess or deficiency. Vitamins are classified into water-soluble and fat-soluble components. The fat-soluble vitamins include vitamins (A, D, E, and K). Fat-soluble vitamins were found to have an indisputable role in an array of physiological processes such as immune regulation, vision, bone and mental health. Nonetheless, the fat-soluble vitamins are now considered a prophylactic measurement for a multitude of diseases such as autism, rickets disease, gestational diabetes, and asthma. Herein, in this review, a deep insight into the orchestration of the four different fat-soluble vitamins requirements is presented for the first time across the human life cycle beginning from fertility, pregnancy, adulthood, and senility with an extensive assessment ofthe interactions among them and their underlying mechanistic actions. The influence of sex for each vitamin is also presented at each life stage to highlight the different daily requirements and effects.

Prenatal and child vitamin D levels and allergy and asthma in childhood

BACKGROUND

Early-life vitamin D deficiency may impair immune system development contributing to allergy and asthma onset. Findings from prospective studies are inconsistent.

OBJECTIVE

To examine whether maternal and child vitamin D levels are associated with allergic and asthma-related symptoms throughout childhood in a Spanish birth cohort.

METHODS

25-Hydroxyvitamin D₃ (25(OH)D₃) levels were measured in the serum of pregnant women (N = 2525) and children (N = 803). Information on allergic and asthma-related symptoms was obtained from repeated questionnaires from 1 to 9 years.

RESULTS

A total of 19% of mothers and 24% of children had deficient 25(OH)D₃ levels (<20 ng/ml). Higher child 25(OH)D₃ levels at 4 years were associated with lower odds of atopic eczema from 4 to 9 years (adjusted odds ratio = 0.90; 95% CI = 0.84-0.97 per 5 ng/ml). Higher maternal and child 25(OH)D₃ levels were associated with a lower prevalence of late-onset wheezing at the limit of statistical significance (adjusted relative risk ratio (RRR_adj) = 0.86; 95% CI = 0.74-1.00 and RRR_adj = 0.76; 95% CI = 0.58-1.02 per 5 ng/ml, respectively). All the remaining associations were null.

CONCLUSION

Child 25(OH)D₃ levels at pre-school age are associated with a reduced odds of atopic eczema in later childhood and both maternal and child levels may reduce the prevalence of late-onset wheezing.

IMPACT

In this Spanish birth cohort, with a total of 19% of mothers and 24% of children with deficient levels of vitamin D, higher child vitamin D at 4 years of age was associated with reduced odds of atopic eczema up to 9 years. There was also some evidence that higher maternal and child vitamin D levels reduced the prevalence of late-onset wheezing. Although these findings need replication, they may imply optimal vitamin D levels at pre-school age to prevent atopic eczema.

Relationship between Acute Respiratory Tract Infection and the Serum 25(OH) D3 Level in Chronic Kidney Disease Patients and Its Prevention and Treatment

Observational studies and randomized controlled studies propose that vitamin D plays a significant role in preventing acute respiratory tract infection (RTI); however, results are inconsistent and the optimal serum 25-hydroxyvitamin D (25-OH-D3) concentration remains unknown. This study explores the risk factors associated with acute RTI in patients with chronic kidney disease (CKD) and analyzes its correlation with serum 25-OH-D3 levels, to provide appropriate preventive treatment measures for CKD patients complicated with acute RTI. Seventy cases of CKD patients treated in the department of nephrology of Jiangxi Provincial People’s Hospital are recruited as the research objects and divided into a control group (CKD without RTI) and an observation group (CKD with RTI), with 35 cases in each group. The laboratory indexes and serum 25-OH-D3 levels are compared between the two groups. The area under the receiver operating characteristic curve (ROC) of 25-OH-D3 in the diagnosis of CKD patients complicated with RTI is 0.892, and the standard error is 0.038. The glomerular filtration rates (GFR) are $48.32\pm 9.87\text{mL}/\min$ and $50.18\pm 20.71\text{mL}/\min$ in the control group and the experimental group, respectively, with no statistical significance between the two groups ( $P>0.05$ ). The serum 25-OH-D3 content in the control group ( $35.08\pm 6.2\text{nmol}/\text{L}$ ) is dramatically higher than that in the observation group ( $20.71\pm 5.87\text{nmol}/\text{L}$ ) ( $P<0.05$ ). The proportion of patients with diabetes mellitus (DM) in the control group and observation group is 25.71% and 68.57%, respectively, with a considerable difference ( $P<0.05$ ). In the control group and the experimental group, the proportion of patients with oral vitamin D receptor agonists is 54.29% and 11.43%, respectively, and the difference is significant ( $P<0.05$ ). Results show that the serum 25-OH-D3 level is highly correlated with the occurrence of RTI in CKD patients. In addition, it is related to patients’ age, DM, and vitamin D receptor agonists.

The role of prenatal vitamin D on the development of childhood asthma and wheeze: An umbrella review of systematic reviews and meta-analyses

BACKGROUND & OBJECTIVE

It has been suggested that prenatal vitamin D plays a role in the development of childhood asthma and wheeze. Several systematic reviews have been conducted, but the results are inconsistent, and the methodological quality has not been studied. Therefore, the objective of this umbrella review was to assess the internal validity of the evidence base and the evidence for an association between prenatal vitamin D and asthma or wheezing in the offspring.

METHODS

We searched the electronic databases Embase, PubMed, and Cochrane Library for studies on prenatal vitamin D using search words such as vitamin D, 25-hydroxyvitamin D, calcidiol, fetal, and neonatal. The search was conducted in June 2020, and the databases were searched from their date of establishment. We included systematic reviews and/or meta-analyses of experimental and observational studies assessing the association between prenatal vitamin D or asthma and wheeze. We excluded narrative reviews, commentaries, and other umbrella reviews. The methodological quality of systematic reviews was assessed using AMSTAR 2 tool. PROSPERO reg. no. CRD42020151329.

RESULTS

We identified 22 eligible systematic reviews (17 on asthma and 20 on wheeze). Using the AMSTAR 2 quality assessment tool, the methodological quality was rated as critically low in 21 out of 22 systematic reviews, suggesting that previous reviews and meta-analyses did not provide accurate and comprehensive summaries of the included studies and that conclusions reached were potentially flawed. The majority of the included reviews reported that prenatal vitamin D reduces the risk of wheeze in the offspring.

CONCLUSION

Prior to informing public guidelines, high-quality systematic reviews of the current evidence are greatly warranted.

Atopic heredity modifies the association between maternal vitamin D status in pregnancy and the risk of atopic disease in childhood: an observational study

Background

The relationship between maternal vitamin D status in pregnancy and the development of atopic diseases in the offspring has been frequently studied, but with contradictory results. Previous studies have found an inverse relation between maternal vitamin D in pregnancy and the risk of atopic diseases in the child. In contrast, others have found a higher maternal 25OHD to be related to a higher risk of atopic diseases. Thus, the aim was to investigate the associations between maternal vitamin D status and intake in pregnancy with asthma, eczema and food allergies in the children up to 5 years. In addition, effect modification by reported atopic heredity was studied.

Methods

Participants in the GraviD study had 25-hydroxyvitamin D (25OHD) analyzed in serum in early (T1) and late (T3) pregnancy. Maternal dietary vitamin D intake was estimated from a short food frequency questionnaire and supplement use by questionnaires. At 5 years of age the child´s history of asthma, eczema and food allergy, including atopic heredity, was reported by questionnaire. Multivariable logistic regression was used.

Results

The cumulative incidence of asthma was 13%, eczema 22%, and food allergy 18%. Only among children without reported atopic heredity, maternal 25OHD of 50–75 nmol/L in T1 was associated with lower odds of asthma (OR 0.271, 95% CI 0.127–0.580), compared to maternal 25OHD > 75 nmol/L. Additionally in these children, maternal 25OHD in T3 (continuous) was associated with asthma (OR 1.014, 95% CI 1.002–1.009), and dietary vitamin D intake with eczema (OR 1.141, 95% CI 1.011–1.288).

Conclusions

Among children without reported atopic heredity, higher maternal vitamin D status and intake during pregnancy was associated with increased risk of reported atopic disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12937-022-00787-9.

Pre- and Postnatal Vitamin D Status and Allergy Outcomes in Early Childhood

The dramatic increase in the prevalence of allergic disease in recent decades reflects environmental and behavioural changes that have altered patterns of early immune development. The very early onset of allergic diseases points to the specific vulnerability of the developing immune system to environmental changes and the development of primary intervention strategies is crucial to address this unparalleled burden. Vitamin D is known to have immunomodulatory functions. While allergic disease is multifactorial, associations with reduced sunlight exposure have led to the hypothesis that suboptimal vitamin D levels during critical early periods may be one possible explanation. Interventions to improve vitamin D status, especially in early life, may be the key to allergic disease prevention.

What are the highest yielding search strategy terms for systematic reviews in atopic dermatitis? A systematic review

The impact of search strategies on systematic reviews (SR) of atopic dermatitis (AD) is unknown. The purpose of this review was to evaluate search strategies used in SR of AD and their impact on the frequency of manuscripts identified. MEDLINE and EMBASE were searched for SR related to AD. Simulations were performed by running combinations of search terms in MEDLINE and EMBASE. Overall, 250 SR met inclusion criteria, of which 225 specified search strategies. SR using 5-6 terms (20.0% to 12.1%) or ≥ 7 (40.0% to 18.8%) terms decreased, whereas SR using 3-4 terms numerically increased (18.8% to 30.2%) and 1-2 terms remained similar (37.5% to 38.9%) from 1999-2009 to 2015-2019. The most commonly searched terms were "atopic dermatitis" (n = 166), followed by "eczema" (n = 156), "dermatitis atopic'" (n = 81), "atopic eczema" (n = 74), "neurodermatitis" (n = 59), "Besniers prurigo" (n = 29), "infantile eczema" (n = 27), and "childhood eczema" (n = 19). Simulations revealed that "eczema" and "atopic dermatitis" yielded the most hits. The number of search terms that maximized hits in MEDLINE and EMBASE was 5 and 4, respectively. Search strategies for AD were heterogeneous, with high proportions of search strategies providing few search hits. Future studies should use standardized and optimized search terms.

Childhood asthma- pathogenesis and phenotypes

In the pathogenesis of asthma in children there is a pivotal role for a type 2 inflammatory response to early life exposures or events. Interactions between infections, atopy, genetic susceptibility, and environmental exposures (such as farmyard environment, air pollution, tobacco smoke exposure) influence the development of wheezing illness and the risk for progression to asthma. The immune system, lung function and the microbiome in gut and airways develop in parallel and dysbiosis of the microbiome may be a critical factor in asthma development. Increased infant weight gain and preterm birth are other risk factors for development of asthma and reduced lung function. The complex interplay between these factors explains the heterogeneity of asthma in children. Subgroups of patients can be identified as phenotypes based on clinical parameters, or endotypes, based on a specific pathophysiological mechanism. Paediatric asthma phenotypes and endotypes may ultimately help to improve diagnosis of asthma, prediction of asthma development and treatment of individual children, based on clinical, temporal, developmental or inflammatory characteristics. Unbiased, data-driven clustering, using a multidimensional or systems biology approach may be needed to better define phenotypes. The present knowledge on inflammatory phenotypes of childhood asthma has now been successfully applied in the treatment with biologicals of children with severe therapy resistant asthma, and it is to be expected that more personalized treatment options may become available.

Immunologic Strategies for Prevention of Asthma

A new understanding of factors leading to the development of asthma has pointed to potential primary, secondary, and tertiary prevention strategies. Some, such as genetic makeup, are not yet modifiable. Interventions targeting other factors such as maternal intake of vitamin D or environmental control can be used to decrease the risk of asthma development (primary prevention). The benefits of a diversified microbiome could be considered when recommending allergen avoidance and pet ownership. In addition to reducing symptoms, allergen immunotherapy is also worth considering for prevention of new sensitivities (secondary prevention) in addition to the development of asthma. Ongoing studies involving the use of bacterial vaccines and biologics may provide additional strategies for primary prevention of asthma and for reducing symptoms once it has developed (tertiary prevention). As the relative benefits of these strategies are defined, they should have an increasingly important place in the prevention and management of asthma.

Prenatal vitamin D levels and child wheeze and asthma

Background: Maternal vitamin D status during pregnancy may influence lung development and risk of childhood wheeze and asthma. We investigated the relationship between prenatal vitamin D and child asthma in a racially diverse cohort with a high burden of vitamin D insufficiency and child asthma.Materials and methods: We included mother-child dyads in the prenatal Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) cohort (2006-2011, Shelby County, Tennessee). Maternal plasma vitamin D [25(OH)D] was measured from second trimester (n = 1091) and delivery specimens (n = 907). At age 4-6 years, we obtained parent report of current child wheeze (symptoms within the past 12 months) and asthma (physician diagnosis and/or medication or symptoms within the past 12 months). We used multivariable logistic regression to assess associations of 25(OH)D and child wheeze/asthma, including an interaction term for maternal race.Results: Median second trimester 25(OH)D levels were 25.1 and 19.1 ng/ml in White (n = 366) and Black women (N = 725), respectively. We detected significant interactions by maternal race for second-trimester plasma 25(OH)D and child current wheeze (p = .014) and asthma (p = .011). Odds of current wheeze and asthma decreased with increasing 25(OH)D in dyads with White mothers and increased in dyads with Black mothers, e.g. adjusted odds ratio (95% confidence interval) for asthma: 0.63 (0.36-1.09) and 1.41 (1.01-1.97) per interquartile range (15-27 ng/ml 25[OH]D) increase, respectively. At delivery, protective associations in White dyads were attenuated.Conclusion: We detected effect modification by maternal race in associations between prenatal 25(OH)D and child wheeze/asthma. Further research in racially diverse populations is needed.

Long and winding road: from infant wheeze to adult asthma

PURPOSE OF REVIEW

This review aims to recognize the multifactorial cause of asthma, from the influence of mother until adulthood, highlight the main characteristics of the disease at different ages and summarize the evidence of potential prevention strategies.

RECENT FINDINGS

To date, regarding the prenatal period, the presence of specific genes, maternal asthma, drugs, and tobacco exposure are the most relevant predisposing features for an asthmatic offspring. For newborns, preterm, bronchopulmonary dysplasia, and low birth weight has been associated with low lung function. Among young children, atopic dermatitis, lower respiratory tract infections, and increased levels of total Immunoglobulin E (IgE) and allergen-specific IgE are important determinants.Breastfeeding has been demonstrated being protective for the onset of asthma. Allergen immunotherapy has also been shown to have significant preventive effect decreasing asthma development. Inhaled corticosteroids use in early childhood prevents exacerbations but does not alter the natural history of asthma. Other interventions, such as the use of palivizumab, probiotics, vitamin D supplementation, and fish consumption presented controversial results.

SUMMARY

A good knowledge of risk factors for asthma development, from prenatal period to adulthood, may lead to efficacious preventive strategies. Further data of long-term follow-up in population-based studies according to different phenotypes are needed.

Low Vitamin D Levels at Birth and Early Respiratory Outcome in Infants With Gestational Age Less Than 29 Weeks

BACKGROUND

Vitamin D (VitD) is involved in lung development but its influence on respiratory distress syndrome of extremely preterm (EPT) infants have been little investigated. In this study, we examined the influence of low vitamin D status at birth on early respiratory outcomes of this vulnerable infant population.

METHODS

Cord blood 25(OH)D levels ≤ 75 nmol/L were considered as Low vitamin D levels. Stepwise logistic regression and classification regression-tree analyses were used and the primary outcome was the combined outcome of death or mechanical ventilation need by the end of the first week (death or MV DoL7) as a marker od RDS severity.

RESULTS

The mean (SD) GA and birth weight were 26 (1.4) weeks and 801 (212) gr, respectively; 81/109 (74%) infants had low 25(OH)D levels. Infants with low VitD levels had 25% higher initial FiO₂ levels (p < 0.05) and were more likely to be mechanically ventilated on DoL7 (36 vs. 7%, p < 0.05). Adjusted for gestational age, they had 10-fold higher odds of death or MV DoL7 (p < 0.01). By regression tree analysis, the rate of death or MV DoL7 increased from 18 to 71% in infants with GA < 26 weeks and with cord blood 25(OH)D levels higher and lower than 74 nmol/L, respectively (p < 0.05).

CONCLUSION

Low vitamin D levels at birth are associated with early adverse respiratory outcomes in infants with GA less 29 weeks. Further largest studies are needed to confirm this association.

Early-Life Effects of Vitamin D: A Focus on Pregnancy and Lactation

Vitamin D is an endocrine regulator of calcium and bone metabolism. Yet, its effects include other systems, such as innate and adaptive immunity. Unique to pregnancy, circulating 1,25-dihydroxyvitamin D (1,25[OH]2D) increases early on to concentrations that are 2-3 times prepregnant values. At no other time during the lifecycle is the conversion of 25-hydroxyvitamin D (25[OH]D) to 1,25(OH)2D directly related and optimized at ≥100 nmol/L. Vitamin D deficiency appears to affect pregnancy outcomes, yet randomized controlled trials of vitamin D supplementation achieve mixed results depending on when supplementation is initiated during pregnancy, the dose and dosing interval, and the degree of deficiency at the onset of pregnancy. Analysis of trials on an intention-to-treat basis as opposed to the use of 25(OH)D as the intermediary biomarker of vitamin D metabolism yields differing results, with treatment effects often noted only in the most deficient women. Immediately after delivery, maternal circulating 1,25(OH)2D concentrations return to prepregnancy baseline, at a time when a breastfeeding woman has increased demands of calcium, beyond what was needed during the last trimester of pregnancy, making one question why 1,25(OH)2D increases so significantly during pregnancy. Is it to serve as an immune modulator? The vitamin D content of mother's milk is directly related to maternal vitamin D status, and if a woman was deficient during pregnancy, her milk will be deficient unless she is taking higher doses of vitamin D. Because of this relative "deficiency," there is a recommendation that all breastfed infants receive 400 IU vitamin D3/day starting a few days after birth. The alternative - maternal supplementation with 6,400 IU vitamin D3/day, effective in safely raising maternal circulating vitamin D, that of her breast milk, and effective in achieving sufficiency in her recipient breastfeeding infant - remains a viable option. Additional research is needed to understand vitamin D's influence on pregnancy health and the effect of maternal supplementation on breast milk's immune signaling.

Low vitamin D and risk of bacterial pneumonias: Mendelian randomisation studies in two population-based cohorts

BACKGROUND

Vitamin D may regulate the innate immune system, and randomised controlled trials suggest a beneficial effect of vitamin D supplementation against acute respiratory tract infections. By using a Mendelian randomisation approach, we tested the hypothesis that low 25-hydroxyvitamin D is associated with increased risk of bacterial pneumonia in observational and genetic analyses.

METHODS

We genotyped 116 335 randomly chosen white Danes aged 20 to 100 from the Copenhagen City Heart Study and Copenhagen General Population Study for plasma 25-hydroxyvitamin D decreasing genetic variants around CYP2R1 (rs117913124, rs12794714 and rs10741657), DHCR7 (rs7944926 and rs11234027), GEMIN2 (rs2277458) and HAL (rs3819817). Information on plasma 25-hydroxyvitamin D was available on 35 833 individuals. Individuals were followed from 1981 through 2018 for hospital diagnoses of bacterial pneumonias.

RESULTS

During up to 38 years follow-up, we observed 6342 bacterial pneumonias in observational analyses and 13 916 in genetic analyses. In observational analyses, multivariable adjusted HR for bacterial pneumonias was 1.27 (95% CI: 1.16 to 1.40) for individuals with 25-hydroxyvitamin D<25 nmol/L compared with those with ≥25 nmol/L. In genetic analyses, the OR for bacterial pneumonia per 10 nmol/L lower plasma 25-hydroxyvitamin D was 1.12 (95% CI: 1.02 to 1.23) in Wald's ratio, 1.12 (95% CI: 1.04 to 1.20) in inverse-variance weighted, 1.63 (95% CI: 0.96 to 2.78) in MR-Egger and 1.15 (95% CI: 1.05 to 1.26) in weighted median instrumental variable analysis. This association was strongest for genetic variants around CYP2R1. There was no observational or genetic evidence to support that 25-hydroxyvitamin D is associated with risk of urinary tract infections, skin infections, sepsis or gastroenteritis, which were used as negative control outcomes.

CONCLUSIONS

Low vitamin D is associated observationally and genetically with increased risk of bacterial pneumonias.

Null association between serum 25-hydroxyvitamin D levels with allergic rhinitis, allergic sensitization and non-allergic rhinitis: A Mendelian randomization study

BACKGROUND

Previous observational studies have not found a conclusive association between serum 25-hydroxyvitamin D (25(OH)D) levels and allergic rhinitis (AR) or allergic sensitization (AS).

OBJECTIVE

To investigate a causal association between 25(OH)D levels with risk of AR and AS, using a two-sample Mendelian randomization (MR) approach.

METHODS

Seven single nucleotide polymorphisms (SNPs), previously shown to be associated with serum 25(OH)D levels, were identified as instrumental variables. The primary outcome was AR, and the secondary outcomes were AS and non-allergic rhinitis (NAR). The genome-wide association (GWA) summary statistics of the outcomes were obtained from two cohort studies (EAGLE Consortium and UK Biobank). An MR analysis with random-effects inverse-variance weighted method was performed as the primary analysis to estimate overall effect size (odds ratio [OR] and 95% confidence interval [CI]). Sensitivity analysis using weighted median method and MR-Egger regression method was conducted. A subgroup analysis based on 25(OH)D synthesis-related SNPs was further applied.

RESULTS

Serum 25(OH)D levels were not causally associated with risk of AR (OR: 0.960; 95% CI: 0.779-1.184), AS (OR: 1.059; 95% CI: 0.686 to 1.634) or NAR (OR: 0.937; 95% CI: 0.588-1.491). Subgroup analysis also showed null association between 25(OH)D synthesis-related SNPs and the outcomes. Sensitivity analyses yielded similar results.

CONCLUSIONS AND CLINICAL RELEVANCE

This MR study found no evidence supporting a causal association between serum 25(OH)D levels and risk of AR, AS and NAR in European-ancestry population. This argues against the previous postulation that vitamin D supplementation is effective in prevention of allergic diseases.

Allergy Modulation by N-3 Long Chain Polyunsaturated Fatty Acids and Fat Soluble Nutrients of the Mediterranean Diet

The Mediterranean diet, containing valuable nutrients such as n-3 long chain poly-unsaturated fatty acids (LCPUFAs) and other fat-soluble micronutrients, is known for its health promoting and anti-inflammatory effects. Its valuable elements might help in the battle against the rising prevalence of non-communicable diseases (NCD), including the development of allergic diseases and other (chronic) inflammatory diseases. The fat fraction of the Mediterranean diet contains bioactive fatty acids but can also serve as a matrix to dissolve and increase the uptake of fat-soluble vitamins and phytochemicals, such as luteolin, quercetin, resveratrol and lycopene with known immunomodulatory and anti-inflammatory capacities. Especially n-3 LCPUFAs such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) derived from marine oils can target specific receptors or signaling cascades, act as eicosanoid precursors and/or alter membrane fluidity and lipid raft formation, hereby exhibiting anti-inflammatory properties. Beyond n-3 LCPUFAs, fat-soluble vitamins A, D, E, and K1/2 have the potential to affect pro-inflammatory signaling cascades by interacting with receptors or activating/inhibiting signaling proteins or phosphorylation in immune cells (DCs, T-cells, mast cells) involved in allergic sensitization or the elicitation/effector phase of allergic reactions. Moreover, fat-soluble plant-derived phytochemicals can manipulate signaling cascades, mostly by interacting with other receptors or signaling proteins compared to those modified by fat-soluble vitamins, suggesting potential additive or synergistic actions by applying a combination of these nutrients which are all part of the regular Mediterranean diet. Research concerning the effects of phytochemicals such as polyphenols has been hampered due to their poor bio-availability. However, their solubility and uptake are improved by applying them within the dietary fat matrix. Alternatively, they can be prepared for targeted delivery by means of pharmaceutical approaches such as encapsulation within liposomes or even unique nanoparticles. This review illuminates the molecular mechanisms of action and possible immunomodulatory effects of n-3 LCPUFAs and fat-soluble micronutrients from the Mediterranean diet in allergic disease development and allergic inflammation. This will enable us to further appreciate how to make use of the beneficial effects of n-3 LCPUFAs, fat-soluble vitamins and a selection of phytochemicals as active biological components in allergy prevention and/or symptom reduction.

The Role of Vitamin D in Respiratory Allergies Prevention. Why the Effect Is so Difficult to Disentangle?

Asthma and allergic rhinitis are the most common chronic childhood diseases with an increasing prevalence worldwide. There is an urgent need to look for methods of preventing allergic diseases from an early age. The relationship between vitamin D status and allergic diseases has been discussed in several studies recently. 25-hydroxyvitamin D (25(OH)D) is suggested to affect the development and/or severity of asthma and allergic rhinitis. Observational studies have seemed to confirm that vitamin D deficiency may contribute to an increase in allergy and asthma. Following interventional studies, however, have yielded ambiguous results. In this review, we describe recent findings regarding 25(OH)D impact on allergic diseases and provide a systematic analysis of the causes of great variability of the achieved results in different studies.

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.

Nutritional Factors in the Prevention of Atopic Dermatitis in Children

Atopic dermatitis is one of the most frequent chronic skin diseases worldwide and often develops within the first few years of life. Recent advancements in our knowledge of its pathophysiology have brought to light the role of genetic predisposition and environmental triggers. With the increasing prevalence of allergic diseases, there is a strong need for a better understanding of the various modifiable eliciting factors of such conditions. The concomitant rise in food allergy and insights into the skin barrier function has highlighted the role of nutrition and diet in the prevention and modification of allergic disorders. Furthermore, the identification of the skin as an important route of sensitization, and the risk of progression to asthma later in life, stress the significance of optimizing our management of skin inflammation in the prevention of allergies. Many nutritional factors, including the type of maternal diet during pregnancy, the duration of breastfeeding, the epicutaneous exposure of allergenic food proteins in the first few years of life, the timing of the introduction of complementary foods, the supplementation of vitamins and probiotics/prebiotics during prenatal and early life, have been assessed as potential targets for the prevention of atopy and eczema. Here, we review the latest data addressing prenatal and perinatal nutritional and dietary interventions in the primary prevention of atopic dermatitis. Also, we define knowledge gaps and targets for future research in the prevention of atopic dermatitis.

The Role of Vitamin D Deficiency in Children With Recurrent Wheezing-Clinical Significance

Recurrent wheezing (RW) in infancy is one of the most frequent reasons for parents to consult health care providers and creates a significant global burden. Clinical course of RW is difficult to predict, also which infants will progress to asthma, since no valid biomarkers have been established. Identification of those infants with RW who are at risk of further recurrences and/or severe acute respiratory tract infection (ARTI) could help pediatricians to improve their therapeutic decisions. Increasing research interest is focused on the extra-skeletal actions of vitamin D (VD) and the clinical impact of VD insufficiency/deficiency. As VD deficiency could be a risk factor for causing RW in children, measurement of their serum level of 25-hydroxycholecalciferol [25(OH)D] is recommended. In the case of deficiency, VD administration is recommended in age-appropriate doses for at least 6 weeks, until achievement of normal blood 25(OH)D level, followed by supplementation as long as exposure to sun is inadequate. Higher doses of VD given in an attempt to prevent asthma development appear to be of no additional benefit. In children with severe ARTI, VD level is recommended to be assess.

Dietary Interventions and Nutritional Factors in the Prevention of Pediatric Asthma

Asthma is the most frequent chronic disease in children, and its pathogenesis involves genetic, epigenetic, and environmental factors. The rapid rise in the prevalence of asthma registered over the last few decades has stressed the need to identify the environmental and modifiable factors associated with the development of the disease. In particular, there is increasing interest in the role of modifiable nutritional factors specific to both the prenatal and post-natal early life as, during this time, the immune system is particularly vulnerable to exogenous interferences. Several dietary factors, including maternal diet during pregnancy, the duration of breastfeeding, the use of special milk formulas, the timing of the introduction of complementary foods, and prenatal and early life supplementation with vitamins and probiotics/prebiotics, have been addressed as potential targets for the prevention of asthma. In this review, we outline recent findings on the potential role of prenatal and perinatal dietary and nutritional interventions for the primary prevention of pediatric asthma. Moreover, we addressed unmet needs and areas for future research in the prevention of childhood-onset asthma.

The effect of an educational program for pregnant women to prevent allergic diseases in infants: study protocol for a randomized controlled trial

BACKGROUND

Allergic diseases in infants have dramatically increased in developed countries during the past few decades. To date, extensive research has been done on risk factors for allergies in infancy, and preventive measures against them. However, the effect of the primary approach to preventing infantile allergy is still limited. The aim of this trial is to evaluate whether prenatal education interventions, including the latest public research results on allergic diseases, prevent the onset of infant allergies.

METHODS/DESIGN

We designed a randomized controlled, two-arm (standard prenatal education vs our education), parallel-group, assessor-blind trial. A sample of 120 pregnant women will be recruited at Chiba Aiyu-kai Kinen Hospital and allocation is by computer-generated randomization. Pregnant women in the intervention arm participate in the childbirth education program established by the specialist and a pediatric allergy educator. The program was developed based on evidences supporting interventions on primary prevention, which are suggested to be beneficial to infantile allergies in recent studies. The primary objective of the study is to determine whether it is possible to establish effective behaviors for allergy prevention in early infancy in the children of pregnant women who participate in an educational program developed by pediatric allergy specialists. Four months after birth, their behaviors will be compared against those of pregnant women who did not participate in the program.

DISCUSSION

Allergies are common in many individuals worldwide, and can be present from babyhood through the person's lifetime. One of the strong points of this study is that it should provide pregnant women with accumulated information on preventive knowledge against allergy, that can be effective in some cases, and that women can apply a combination of these behaviors before and after pregnancy. The results of our program will be publicized to help change the behaviors of mothers, and, if the program is effective, for preventing allergies in infants, it will be disclosed worldwide as a new preventive strategy for allergy in infants.

TRIAL REGISTRATION

UMIN-CTR, ID: UMIN000034730 Retrospectively registered on 1 December 2018.

Potential Strategies and Targets for the Prevention of Pediatric Asthma

Asthma is the most common chronic disease of childhood in developed countries, with a continually increasing prevalence. The paradigm of asthma control is shifting from disease management to primary prevention, and the modification of numerous host and external factors have been proposed as methods to prevent recurrent wheeze and asthma in children, some with promising preliminary results. This article reviews potential asthma prevention strategies and identifies future areas of research.

Highlights and recent developments in airway diseases in EAACI journals (2018)

The European Academy of Allergy and Clinical Immunology (EAACI) supports three journals: Allergy, Pediatric Allergy and Immunology, and Clinical and Translational Allergy. EAACI's major goals include supporting the promotion of health, in which the prevention of allergy and asthma plays a critical role, and disseminating the knowledge of allergic disease to all stakeholders. In 2018, the remarkable progress in the identification of basic mechanisms of allergic and respiratory diseases as well as the translation of these findings into clinical practice were observed. Last year's highlights include publication of EAACI guidelines for allergen immunotherapy, many EAACI Position Papers covering important aspects for the specialty, better understanding of molecular and cellular mechanisms, identification of biomarkers for disease prediction and progress monitoring, novel prevention and intervention studies, elucidation of mechanisms of multimorbidities, introduction of new drugs to the clinics, recently completed phase three clinical studies, and publication of a large number of allergen immunotherapy studies and meta-analyses.

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.

AllergoOncology: Microbiota in allergy and cancer-A European Academy for Allergy and Clinical Immunology position paper

The microbiota can play important roles in the development of human immunity and the establishment of immune homeostasis. Lifestyle factors including diet, hygiene, and exposure to viruses or bacteria, and medical interventions with antibiotics or anti-ulcer medications, regulate phylogenetic variability and the quality of cross talk between innate and adaptive immune cells via mucosal and skin epithelia. More recently, microbiota and their composition have been linked to protective effects for health. Imbalance, however, has been linked to immune-related diseases such as allergy and cancer, characterized by impaired, or exaggerated immune tolerance, respectively. In this AllergoOncology position paper, we focus on the increasing evidence defining the microbiota composition as a key determinant of immunity and immune tolerance, linked to the risk for the development of allergic and malignant diseases. We discuss novel insights into the role of microbiota in disease and patient responses to treatments in cancer and in allergy. These may highlight opportunities to improve patient outcomes with medical interventions supported through a restored microbiome.

Maternal and neonatal 25-hydroxyvitamin D concentrations and school-age lung function, asthma and allergy. The Generation R Study

BACKGROUND

Vitamin D deficiency in early life might affect the developing lung and immune system, and subsequently influence the risk of asthma and allergy in later life.

OBJECTIVE

We examined the associations of 25-hydroxyvitamin D concentrations in mid-gestation and at birth with lung function, asthma, inhalant allergic sensitization and inhalant allergy at school-age.

METHODS

This study among 4951 children and their mothers was embedded in a population-based prospective cohort in Rotterdam, the Netherlands. Maternal venous blood samples in mid-gestation and umbilical cord blood samples at birth were used to determine 25-hydroxyvitamin D concentrations. At age 10 years, lung function was measured by spirometry, current asthma and physician-diagnosed inhalant allergy by questionnaire, and inhalant allergic sensitization by skin prick tests. We used multivariable regression models to examine associations.

RESULTS

Higher 25-hydroxyvitamin D concentrations in mid-gestation were associated with a higher forced vital capacity (FVC), but a lower forced expiratory volume in 1 second/FVC (FEV₁ /FVC) and a lower forced expiratory flow after exhaling 75% of FVC (FEF₇₅ ) (Z-score differences [95% CI] 0.02 [0.00, 0.03], -0.02 [-0.03, -0.01] and -0.01 [-0.03, -0.00], respectively, per 10 nmol/L 25-hydroxyvitamin D), but not with asthma. Furthermore, higher 25-hydroxyvitamin D concentrations in mid-gestation were associated with an increased risk of inhalant allergy (Odds Ratio [95% CI] 1.07 [1.02, 1.12]), but not with inhalant allergic sensitization. After additional adjustment for child's 25-hydroxyvitamin D concentrations at the age of 6 years, only the associations of 25-hydroxyvitamin D concentrations in mid-gestation with FEV₁ /FVC and FEF₇₅ remained. We did not find consistent associations of 25-hydroxyvitamin D concentrations at birth with respiratory or allergy outcomes.

CONCLUSION AND CLINICAL RELEVANCE

Our results suggest that maternal 25-hydroxyvitamin D concentrations in mid-gestation may influence lung development. The clinical implications of the observed associations remain unclear.

Exposure to Vitamin D Fortification Policy in Prenatal Life and the Risk of Childhood Asthma: Results From the D-Tect Study

Prenatal vitamin D insufficiency may be associated with an increased risk of developing childhood asthma. Results from epidemiological studies are conflicting and limited by short follow-up and small sample sizes. The objective of this study was to examine if children born to women exposed to the margarine fortification policy with a small dose of extra vitamin D during pregnancy had a reduced risk of developing asthma until age 9 years, compared to children born to unexposed women. The termination of a Danish mandatory vitamin D fortification policy constituted the basis for the study design. We compared the risk of inpatient asthma diagnoses in all Danish children born two years before (n = 106,347, exposed) and two years after (n = 115,900, unexposed) the termination of the policy. The children were followed in the register from 0–9 years of age. Data were analyzed using Cox proportional hazards regression. The Hazard Ratio for the first inpatient asthma admission among exposed versus unexposed children was 0.96 (95%CI: 0.90–1.04). When stratifying by sex and age, 0–3 years old boys exposed to vitamin D fortification showed a lower asthma risk compared to unexposed boys (HR 0.78, 95%CI: 0.67–0.92). Prenatal exposure to margarine fortification policy with extra vitamin D did not affect the overall risk of developing asthma among children aged 0–9 years but seemed to reduce the risk among 0–3 years old boys. Taking aside study design limitations, this could be explained by different sensitivity to vitamin D from different sex-related asthma phenotypes in children with early onset, and sex differences in lung development or immune responses.

Vitamin D status during pregnancy and offspring outcomes: a systematic review and meta-analysis of observational studies

BACKGROUND/OBJECTIVES

Vitamin D deficiency during pregnancy may influence adverse outcomes in offspring. The aim of this systematic review and meta-analysis of observational studies was to assess the association between low prenatal concentrations of 25(OH)D (by using three different cut-off levels), preterm birth (PTB) and anthropometric and neurodevelopmental outcomes in offspring.

SUBJECTS/METHODS

Studies reporting data on the association between maternal vitamin D concentrations and offspring outcomes identified through a systematic review of scientific literature published in PubMed/MEDLINE, Scopus and the Cochrane Library databases up to April 2017.

RESULTS

We included 54 eligible studies. Vitamin D-deficient mothers (<30 nmol/L) had offspring with lower birthweight (MD -87.82 g; 95% CI -119.73, -55.91 g), head circumference (MD -0.19 cm; 95% CI -0.32, -0.06 cm) and a higher risk of small for gestational age (SGA) infants and PTB (OR 1.59; 95% CI 1.24, 2.03) compared to mothers with concentrations ≥30 nmol/L. Vitamin D insufficiency (<50 nmol/L) was associated with a higher risk of SGA and PTB (OR 1.43; 95% CI 1.08, 1.91 and OR 1.28; 95% CI 1.08, 1.52, respectively). Concentrations of 25(OH)D ≥75 nmol/L were not found to be associated with birthweight, SGA or PTB. Offspring of vitamin D-insufficient mothers had lower scores in mental (MD -1.12 points; 95% CI -1.82, -0.42 cm) and language developmental tests (MD -0.35 points; 95% CI -1.00, 0.31 cm).

CONCLUSION

Maternal vitamin D deficiency is associated with offspring adverse anthropometric outcomes and PTB; insufficiency with a higher risk of SGA, PTB and adverse neurodevelopmental outcomes.

The Role of Vitamin D in Fertility and during Pregnancy and Lactation: A Review of Clinical Data

Vitamin D deficiency is common and there exists a huge gap between recommended dietary vitamin D intakes and the poor vitamin D supply in the general population. While vitamin D is important for musculoskeletal health, there are accumulating data suggesting that vitamin D may also be important for fertility, pregnancy outcomes and lactation. Significant changes in vitamin D metabolism during pregnancy such as increased production of the “active vitamin D hormone” calcitriol support the important role of vitamin D in this setting. Observational studies show that vitamin D deficiency is a risk marker for reduced fertility and various adverse pregnancy outcomes and is associated with a low vitamin D content of breast milk. Meta-analyses of randomized controlled trials (RCTs) document that physiological vitamin D supplementation during pregnancy is safe and improves vitamin D and calcium status, thereby protecting skeletal health. Although certain RCTs and/or meta-analyses reported some other beneficial effects, it is still not clear whether vitamin D supplementation improves fertility or decreases the risk of adverse pregnancy outcomes such as low birth weight, pre-eclampsia and neonatal mortality, or reduces wheeze/asthma in the infants. Nevertheless, vitamin D supplementation in pregnant women is frequently required to achieve a sufficient vitamin D status as recommended by nutritional vitamin D guidelines. In this review, we provide an overview of systematic reviews, meta-analyses and large trials reporting clinical data on the role of vitamin D for fertility, pregnancy and lactation.

Nutrition and Lung Growth

Experimental evidence from animal models and epidemiology studies has demonstrated that nutrition affects lung development and may have a lifelong impact on respiratory health. Chronic restriction of nutrients and/or oxygen during pregnancy causes structural changes in the airways and parenchyma that may result in abnormal lung function, which is tracked throughout life. Inadequate nutritional management in very premature infants hampers lung growth and may be a contributing factor in the pathogenesis of bronchopulmonary dysplasia. Recent evidence seems to indicate that infant and childhood malnutrition does not determine lung function impairment even in the presence of reduced lung size due to delayed body growth. This review will focus on the effects of malnutrition occurring at critical time periods such as pregnancy, early life, and childhood, on lung growth and long-term lung function.