Maternal 25-hydroxyvitamin D and its association with childhood atopic outcomes and lung function

"You are my sunshine, my only sunshine": maternal vitamin D status and supplementation in pregnancy and their effect on neonatal and childhood outcomes

Vitamin D (VD) plays a crucial role in regulating calcium homeostasis, while the wealth of its pleiotropic actions is gaining increasing research interest. Sufficient VD concentrations are of clinical relevance, particularly in the context of physiological alterations, such as those occurring during pregnancy when maternal VD is the sole source for the developing fetus. As a result, inadequate VD concentrations in pregnancy have been associated with perinatal complications and adverse neonatal outcomes, including preeclampsia, gestational diabetes mellitus, increased rates of cesarean section, low birth weight, small-for-gestational-age infants, poor immune and skeletal growth, allergies, and respiratory infections. Over the past few decades, several observational studies have underlined the important role of maternal VD in the neural, musculoskeletal, and psychomotor growth and bone health of the offspring. However, the complexity of the factors involved in regulating and assessing VD homeostasis, including race, sun exposure, dietary habits, and laboratory measurement techniques, makes the interpretation of relevant research findings challenging. The aim of this narrative review is to summarize the evidence on the importance of VD in maintaining optimal health during pregnancy, infancy, childhood, and adolescence.

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.

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.

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.

Maternal serum 25-hydroxyvitamin D levels and infant atopic dermatitis: A prospective cohort study

BACKGROUND

Maternal vitamin D status during pregnancy has been linked with the risk of atopic dermatitis (AD) in children, while the results were inconsistent. The objective of this study was to assess the potential association.

METHODS

Serum 25-hydroxyvitamin D (25(OH)D) levels were measured in pregnant women from the birth cohort MKFOAD. Infant AD was diagnosed according to Williams' criteria. Multivariate logistic regression model was used to examine the association of maternal serum 25(OH)D levels in the first, second, and third trimester of gestation with the risk of infant AD at first year of age.

RESULTS

In total, 121 (26.5%) of 456 infants developed AD prior to 1 year of age. In general, higher maternal serum 25(OH)D levels throughout pregnancy were associated with increased risks of AD in infants prior to 1 year of age in multivariate logistic regression models, with borderline statistical significance in the first (per ln unit increase: adjusted OR = 1.93, 95% CI: 0.96, 3.88) and second (per ln unit increase: adjusted OR = 1.72, 95% CI: 0.93, 3.19) trimester. Multivariate logistic regression models using categorical variables of maternal 25(OH)D levels by tertiles showed similar results: Infants born to mothers with serum 25(OH)D levels in the highest tertile had higher risk of AD than those with 25(OH)D in the lowest tertile.

CONCLUSIONS

The present study found some evidence supporting that higher maternal 25(OH)D levels during pregnancy increased the risk of infant AD. However, the clinical implication of the findings should be limited for those with blood levels over the recommendations.

Maternal Nutritional Status and Development of Atopic Dermatitis in Their Offspring

Atopic dermatitis (AD) is the leading chronic skin inflammatory disease and the initial manifestation of atopic march. Available evidence supports the notion that primary prevention early in life leads to a decreased incidence of AD, thus possibly decreasing the subsequent occurrence of atopic march. Nutritional status is essential to a proper functioning immune system and is valued for its important role in AD. Essential nutrients, which include carbohydrates, proteins, lipids, vitamins, and minerals, are transferred from the mother to the fetus through the placenta during gestation. Various nutrients, such as polyunsaturated fatty acids (PUFAs) and vitamin D, were studied in relation to maternal status and offspring allergy. However, no strong evidence indicates that a single nutrient or food in mothers' diet significantly affects the risk of childhood AD. In the light of current evidence, mothers should not either increase nor avoid consuming these nutrients to prevent or ameliorate allergic diseases in their offspring. Each essential nutrient has an important role in fetal development, and current government recommendations suggest specific intake amounts for pregnant women. This review discusses evidence on how various nutrients, including lipids (monounsaturated fatty acids, PUFAs, saturated fatty acids, and short-chain fatty acids), carbohydrates (oligosaccharides and polysaccharides), proteins, vitamins (A, B, C, D, and E), and trace minerals (magnesium, iron, zinc, copper, selenium, and strontium) in maternal status are associated with the development of AD and their possible mechanisms.

Serum 25-Hydroxyvitamin D Concentrations and Atopic Dermatitis in Early Childhood: Findings from the Japan Environment and Children's Study

Vitamin D (VitD) may affect immune system modulation and result in the development of atopic dermatitis (AD). However, published findings have remained controversial. We investigated the association between early-life 25-hydroxyvitamin D (25(OH)D) levels and AD risk at childhood with a birth cohort. The data were obtained from “the Japan Environment and Children’s Study (JECS)” and “the Sub-Cohort study of JECS” performed with children aged 2 years. “Liquid chromatography-tandem mass spectrometry” was used to measure VitD. The information on AD was obtained from parents’ answers to a questionnaire when their children were aged 3 years. In order to explain the seasonal effects on VitD levels, a deseasonalized continuous variable was further calculated. The logistic regression models were fitted to evaluate the effect of VitD on childhood AD. The study included 4378 children with complete data on VitD and AD. The results from models indicated that low VitD at 2 years was not a risk factor for the development of AD at 3 years, after adjusting for potential confounders. Moreover, there was no U-shape relationship between deseasonalized VitD and childhood AD. Overall, early-life 25(OH)D levels were not link to the increased risk of developing childhood AD.

Low gestational vitamin D level and childhood asthma are related to impaired lung function in high-risk children

BACKGROUND

Lung function impairment in early life often persists into adulthood. Therefore, identifying risk factors for low childhood lung function is crucial.

OBJECTIVE

We examined the effect of 25-hydroxyvitamin D (25[OH]D) level and childhood asthma phenotype on childhood lung function in the Vitamin D Antenatal Asthma Reduction Trial (VDAART).

METHODS

The 25(OH)D level was measured at set time points in mothers during pregnancy and in children during early life. On the basis of parental reports, children were categorized into 3 clinical phenotypes: asymptomatic/infrequent wheeze, early transient wheeze, and asthma at age 6 years. Lung function was assessed with impulse oscillometry at ages 4, 5, and 6 years and with spirometry at ages 5 and 6 years.

RESULTS

A total of 570 mother-child pairs were included in this post hoc analysis. Mean gestational 25(OH)D-level quartiles were negatively associated with child respiratory resistance at 5 Hz (R5) from age 4 to 6 years (β, -0.021 kPa/L/s; 95% CI, -0.035 to -0.007; P = .003) and positively associated with FEV₁ (β, 0.018 L; 95% CI, 0.005-0.031; P = .008) and forced vital capacity (β, 0.022 L; 95% CI, 0.009-0.036; P = .002) from age 5 to 6 years. Children with asthma at age 6 years had lower lung function from age 4 to 6 years than the asymptomatic/infrequent wheeze group (β, 0.065 kPa/L/s; 95% CI, 0.028 to 0.102; P < .001 for R5 and β, -0.063 L; 95% CI, -0.099 to -0.028; P < .001 for FEV₁).

CONCLUSIONS

Low gestational 25(OH)D level and childhood asthma are important risk factors for decreased lung function in early childhood.

Neonatal Vitamin D Status and Risk of Asthma in Childhood: Results from the D-Tect Study

Background: low vitamin D status in pregnancy can influence the offspring’s lung function and contribute to childhood asthma development. The objective of this study was to examine the influence of neonatal vitamin D status on the development of asthma among children age 3–9 years in a large population sample. Method: in a case-cohort study utilizing a Danish biobank and register data we examined the association between neonatal 25-hydroxyvitamin D₃ (25(OH)D₃) concentrations and incidence of asthma among children aged 3–9 years. Cases of asthma (n = 911) were randomly selected among all cases of asthma in the Danish National Patient Register from children born between 1992 and 2002. The sub-cohort (n = 1423) was randomly selected among all children born in the same period. We used a weighted Cox proportional hazard model assessing the hazard of first asthma diagnoses by quintiles of 25(OH)D₃. Results: the median 25(OH)D3 (interquartile range) for asthma cases was 23 nmol/L (14–35) and the sub-cohort 25 nmol/L (14–40). The hazard ratio for developing asthma between ages 3 and 9 years was lower for children in the fifth quintile of neonatal 25(OH)D₃ compared to children in the first quintile, both in the unadjusted (0.61 95% CI: 0.46–0.80) and adjusted (0.55 95% CI: 0.39–0.77) analyses. Conclusion: the results from our study suggest that higher neonatal vitamin D concentration may reduce the risk of developing childhood asthma at ages 3–9 years, indicating that neonatal vitamin D status as a proxy of vitamin D status during the prenatal period is important for normal immune- and lung development.

Maternal vitamin D status during pregnancy and offspring risk of childhood/adolescent depression: Results from the Avon Longitudinal Study of Parents and Children (ALSPAC)

BACKGROUND

Low maternal vitamin D levels [serum 25-hydroxyvitamin D (25(OH)D)] during pregnancy have been linked to offspring neuropsychiatric outcomes such as schizophrenia and autism, but studies on depression are lacking. We examined the association between maternal vitamin D status during pregnancy and offspring depression during childhood and adolescence and investigated whether any associations were modified by offspring genetic risk for depression.

METHODS

Mother-singleton birth offspring pairs in the Avon Longitudinal Study of Parents and Children (ALSPAC) that had maternal 25(OH)D measurements, offspring genetic data, and offspring depression measures collected in childhood (mean age=10.6 years; n = 2938) and/or adolescence (mean age=13.8 years; n = 2485) were included in the analyses. Using multivariable logistic regression, we assessed associations between maternal vitamin D status and offspring polygenic risk score (PRS) for depression on childhood/adolescent depression risk.

RESULTS

There was no evidence for an association between maternal vitamin D status during pregnancy and offspring depression in childhood (p = 0.72) or adolescence (p = 0.07). Offspring depression PRS were independently associated with childhood depression (p = 0.003), but did not interact with maternal vitamin D status. These results were robust to adjustments for potential confounders and different cut-offs for vitamin D insufficiency/deficiency.

LIMITATIONS

25(OH)D measurements were only available at a single time point during pregnancy.

CONCLUSION

These findings suggest that maternal vitamin D status during pregnancy does not affect an offspring's risk for early life depression.

Occurrence of pollen season at the end of the first trimester predicts clinical atopic diseases in the offspring: A Finnish population-based study

OBJECTIVE

To evaluate the association between potential exposure to different pollen concentrations at the 11th fetal week and subsequent clinical atopic diseases.

STUDY DESIGN AND SETTING

Parents of 1- to 4-year-old children (N = 3035) returned a questionnaire regarding physician-diagnosed atopic diseases. The children were born between 2001 and 2005 in the province of South Karelia, Finland. Results of allergy tests were collected from patient records in the area.

RESULTS

The prevalence of atopic diseases with sensitisation was higher in children whose 11th fetal week occurred during pollen rather than non-pollen season: atopic eczema 6.3% vs. 4.3% (adjusted odds ratio, aOR 1.58, 95% CI 1.10─2.28), food allergy 5.7% vs. 3.9% (1.63; 1.12─2.38), respiratory allergy or asthma 3.7% vs. 2.2% (2.03; 1.24─3.33) and any atopic diseases 7.4% vs. 5.5% (1.48; 1.07─2.05), respectively. Respectively, the prevalence was higher in the children exposed to high rather than low tree pollen concentrations (>1000 vs. <10 particles/m³) at the 11th fetal week: 12.1% vs. 4.4% (3.35; 1.89─5.95), 12.1% vs. 3.9% (3.77; 2.11─6.72), 4.7% vs. 2.5% (2.95; 1.21─7.20) and 14.0% vs. 5.7% (3.15; 1.86─5.35).

CONCLUSION

Coincidence of potential exposure to high tree pollen concentrations at the 11th fetal week is associated with subsequent clinical atopic diseases with sensitisation.

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.

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.

Antenatal vitamin D exposure and childhood eczema, food allergy, asthma and allergic rhinitis at 2 and 5 years of age in the atopic disease-specific Cork BASELINE Birth Cohort Study

BACKGROUND

Prospective studies of antenatal and infant vitamin D exposure and atopic disease from extensively characterised, disease-specific, maternal-infant cohorts with gold standard analysis of vitamin D status and clinically validated atopic outcomes are lacking. This study aimed to investigate associations between intrauterine vitamin D status and atopic outcomes in an extensively characterised, disease-specific, maternal-infant cohort.

METHODS

Circulating 25-hydroxyvitamin D (25(OH)D) was measured in maternal sera at 15 weeks of gestation (n = 1537) and umbilical cord blood (n = 1050) using a CDC-accredited LC-MS/MS platform, and the association with clinically validated atopic disease outcomes (eczema, food allergy, asthma, allergic rhinitis) at 2 and 5 years was explored using multivariable logistic regression.

RESULTS

Persistent eczema in the first 2 years of life was present in 5% of infants. Food allergy at 2 years was confirmed in 4%. The prevalence of aeroallergen sensitisation at 2 years was 8%. Asthma at 5 years was reported in 15% and allergic rhinitis in 5% of 5-year-olds. There were no significant differences in the distributions of maternal 25(OH)D at 15 weeks of gestation (mean [SD] 58.4 [26.2] and 58.5 [26.1] nmol/L) and cord 25(OH)D concentrations (mean [SD] 35.2 [17.8] and 35.4 [18.3] nmol/L) between children with and without atopic disease. Neither maternal (aOR [95% CI]: 1.02 [0.97, 1.08], P = 0.450) nor cord 25(OH)D (aOR [95% CI]: 1.00 [0.91, 1.09], P = 0.991) were significant predictors of atopic disease outcomes in fully adjusted models.

CONCLUSION

These data in a disease-specific cohort with prospectively collected, validated atopic outcomes do not support an association between antenatal exposure to vitamin D and atopic disease outcomes in childhood.

Early life vitamin D status and asthma and wheeze: a systematic review and meta-analysis

BACKGROUND

Vitamin D deficiency has been linked to an increased risk of asthma. This study aimed to quantify the effect of early life vitamin D status on asthma and wheeze later in life.

METHODS

PubMed, Embase, CINAHL, and CNKI databases, the Cochrane Central Register of Controlled Trials, and Google Scholar were searched up to July 2017. We included randomized controlled trials (RCTs) and cohort studies with vitamin D level in blood (maternal or cord or infant) or intake (maternal intake during pregnancy or infant intake) and asthma and/or wheeze. Two reviewers independently extracted data. Fixed- and random-effects models were used to summarize the risk estimates of comparisons between highest vs. lowest vitamin D categories.

RESULTS

Of the 1485 studies identified, three RCTs and 33 cohort studies were included. We did not include the RCTs (1619 participants) in the meta-analysis as the comparators and outcome definitions were heterogenous. Three RCTs reported a non-statistically significant effect of vitamin D supplementation during pregnancy on offspring wheeze/asthma at 3 years of age. Pooled estimates of cohort studies suggest no association between antenatal blood vitamin D levels or vitamin D intake and offspring asthma assessed either > 5 years or ≤ 5 years. The estimate for blood vitamin D remained unchanged when two studies assessing asthma in adulthood were excluded, but a significant inverse association emerged between vitamin D intake and childhood asthma. We found no association between antenatal vitamin D level and wheeze. On the other hand, vitamin D intake during pregnancy may have a protective effect against wheeze.

CONCLUSIONS

The pooled estimates from cohort studies show no association between antenatal blood vitamin D level and asthma/wheeze in later life. Whereas, the pooled estimates from cohort studies suggest that antenatal vitamin D intake may have an effect on childhood asthma > 5 years or childhood wheeze. The inconsistent results from studies assessing vitamin D either in blood or intake may be explained by previously reported non-linear association between blood vitamin D3 and childhood asthma. Further trials with enough power and longer follow-up time should be conducted to confirm the results.

Vitamin D in pediatric age: consensus of the Italian Pediatric Society and the Italian Society of Preventive and Social Pediatrics, jointly with the Italian Federation of Pediatricians

Vitamin D plays a pivotal role in the regulation of calcium-phosphorus metabolism, particularly during pediatric age when nutritional rickets and impaired bone mass acquisition may occur.Besides its historical skeletal functions, in the last years it has been demonstrated that vitamin D directly or indirectly regulates up to 1250 genes, playing so-called extraskeletal actions. Indeed, recent data suggest a possible role of vitamin D in the pathogenesis of several pathological conditions, including infectious, allergic and autoimmune diseases. Thus, vitamin D deficiency may affect not only musculoskeletal health but also a potentially wide range of acute and chronic conditions. At present, the prevalence of vitamin D deficiency is high in Italian children and adolescents, and national recommendations on vitamin D supplementation during pediatric age are lacking. An expert panel of the Italian Society of Preventive and Social Pediatrics reviewed available literature focusing on randomized controlled trials of vitamin D supplementation to provide a practical approach to vitamin D supplementation for infants, children and adolescents.

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

BACKGROUND

Prenatal vitamin D status may influence offspring's respiratory and allergic outcomes; however, evidence is inconclusive. A systematic review and meta-analysis were conducted on the association between 25-hydroxyvitamin D [25(OH)D] levels in maternal blood in pregnancy or cord blood at birth with the risk of offspring's respiratory and allergic conditions.

METHODS

Two independent researchers conducted systematic searches for observational studies published until May 2017 using defined keywords on vitamin D and health outcomes, including respiratory tract infections (RTIs), wheeze, asthma, atopic eczema, allergic rhinitis, allergic sensitization, and lung function. Random-effects meta-analyses were conducted.

RESULTS

A total of 34 from 547 retrieved articles were included. Increased prenatal exposure to 25(OH)D was inversely associated with risk of RTIs. Comparing the highest with the lowest category of 25(OH)D levels, the pooled odds ratio was 0.64 (95% CI 0.47, 0.87). A positive borderline association was found for lung function at school age (FEV1 z-score coefficient 0.07, 95% CI -0.01, 0.15). No associations were found for wheeze, asthma, atopic eczema, allergic rhinitis, and allergic sensitization.

CONCLUSION

The introduction of public health measures to tackle vitamin D status in pregnancy may reduce the burden of RTIs in offspring. Current evidence does not support an impact on asthma and allergy.

Exposure amount and timing of solar irradiation during pregnancy and the risk of sensitization in children

BACKGROUND

Solar irradiation affects sensitization to aeroallergens and the prevalence of allergic diseases. Little is known, however, about how the time and amount of solar irradiation during pregnancy affects such risks in children. We aimed to find out how solar irradiation during pregnancy affects sensitization to aero-allergens and the prevalence of allergic diseases in children.

METHODS

This population-based cross-sectional study involved 7301 aged 6 years and aged 12 years children. Maternal exposure to solar irradiation during pregnancy was evaluated using data from weather stations closest to each child's birthplace. Monthly average solar irradiation during the second and third trimesters was calculated with rank by quartiles. Risks of allergic sensitization and allergic disease were estimated.

RESULTS

Relative to the first (lowest) quartile, the adjusted odds ratio (aOR) for allergic sensitization in the fourth (highest) quartile was lowest within solar irradiation during pregnancy months 5-6 (aOR = 0.823, 95% CI 0.720-0.942, p < 0.05). During months 9-10, the aOR for allergic sensitization for the fourth was higher than the first quartile of solar irradiation (aOR = 1.167, 95% CI 1.022-1.333, p < 0.05). Similar results were observed when solar irradiation was analyzed as a continuous variable during months 5 (aOR = 0.975, 95% CI 0.962-0.989, p < 0.001) and month 9 (aOR = 1.018, 95% CI 1.004-1.031, p = 0.003). Increased solar irradiation during months 7-8 increased the risk of asthma (aOR = 1.309, 95% CI 1.024-1.674, p = 0.032).

CONCLUSIONS

Maternal exposure to solar irradiation during the second trimester of pregnancy associated with reduced aeroallergen sensitization, whereas solar irradiation during the third trimester was related to increased sensitization to aeroallergens.

Pregnancy diet and offspring asthma risk over a 10-year period: the Lifeways Cross Generation Cohort Study, Ireland

OBJECTIVE

The association of maternal pregnancy diet with offspring asthma risk have been reported. However, literature on longitudinal patterns of asthma risk relative to intrauterine nutrient exposure is limited. We aimed to establish whether vegetable, oily fish and vitamin D intake during pregnancy are associated with childhood asthma risk over a 10-year period in the Irish Republic.

DESIGN

Mother-child pairs (n=897) from the Lifeways prospective birth cohort, with data on nutrient intake during pregnancy and asthma status, respectively, were eligible for inclusion in the analysis. Data on socioeconomic and morbidity indicators over 10 years of follow-up on mothers and the index child were collected through self-administered questionnaires. Asthma status as diagnosed by the general practitioner at any time point over 10 years was related to maternal vegetable, oily fish and vitamin D intake during pregnancy, while adjusting for gestational age, socioeconomic status, smoking at delivery, breast feeding, season of birth and supplement use. Data were modelled with a marginal model on correlated observations over time within individuals.

RESULTS

In the fully adjusted model, asthma was inversely associated with higher daily average intake of oily fish (OR 0.23 per serving/day, 95% CI 0.04 to 1.41) and of vegetables (OR 0.96 per serving/day, 95% CI 0.88 to 1.05), but the confidence limits overlapped 1. A higher daily vitamin D intake was associated with reduced odds of asthma (OR 0.93 per μg/day, 95% CI 0.89 to 0.98).

CONCLUSION

This analysis suggests higher daily average intake of vitamin D in pregnancy is associated with asthma risk in offspring over the first 10 years of life.

Free 25(OH)D concentrations are associated with atopy and lung function in children with asthma

BACKGROUND

Evidence suggests free mono-hydroxyvitamin D (25[OH]D) concentrations are more strongly linked to certain outcomes than total concentrations; however, no studies have examined the relation between free 25(OH)D and respiratory or allergic disease.

OBJECTIVE

To examine associations between total and free 25(OH)D concentrations and asthma outcomes.

METHODS

We quantified total and free 25(OH)D concentrations in 137 Peruvian children with asthma and 152 children without asthma and examined associations with asthma outcomes.

RESULTS

Mean age ± SD was 13 ± 2.5 years, and 50.2% were boys. Mean total and measured free 25(OH)D concentrations were 29 ± 9.5 ng/mL and 5.0 ± 1.3 pg/mL, respectively. Lower free but not total 25(OH)D concentrations were significantly associated with atopy in all children (total, odds ratio [OR] 1.3 per 10-ng/mL decrease, 95% confidence interval [CI] 0.95-1.7, P = .12; vs free, OR 1.3 per 1-pg/mL decrease, 95% CI 1.0-1.6, P = .02) and children with asthma (total, OR 1.1 per 10-ng/mL decrease, 95% CI 0.75-1.7, P = .57; vs free, OR 1.6 per 1-pg/mL decrease, 95% CI 1.0-2.5, P = .04). Free but not total 25(OH)D levels were significantly associated with pre-bronchodilator forced expiratory volume in 1 second (total, 0.11 L, -0.12 to 0.34, P = .34; vs free, 0.20 L, 0.021-0.39, P = .03) and forced vital capacity (total, 0.13 L, -0.12 to 0.37, P = .31; vs free, 0.22 L, 0.026-0.42, P = .03) Z-scores in children with asthma.

CONCLUSION

Atopy, forced expiratory volume in 1 second, and forced vital capacity were more strongly linked to free than to total 25(OH)D concentrations, suggesting the free form might be more relevant in modulating allergic disease risk and pulmonary function in children with asthma.

Maternal vitamin D status during pregnancy and risk of childhood asthma: A meta-analysis of prospective studies

SCOPE

Mounting evidence suggests that maternal vitamin D status during pregnancy may be associated with development of childhood asthma, but the results are still inconsistent. A dose-response meta-analysis was performed to quantitatively summarize evidence on the association of maternal vitamin D status during pregnancy with the risk of childhood asthma.

METHODS AND RESULTS

A systematic search was conducted to identify all studies assessing the association of maternal 25-hydroxyvitamin D (25(OH)D) during pregnancy with risk of childhood asthma. The fixed or random-effect model was selected based on the heterogeneity test among studies. Nonlinear dose-response relationship was assessed by restricted cubic spline model. Fifteen prospective studies with 12 758 participants and 1795 cases were included in the meta-analysis. The pooled relative risk of childhood asthma comparing the highest versus lowest category of maternal 25(OH)D levels was 0.87 (95% confidence interval, CI, 0.75-1.02). For dose-response analysis, evidence of a U-shaped relationship was found between maternal 25(OH)D levels and risk of childhood asthma (P_nonlinearity = 0.02), with the lowest risk at approximately 70 nmol/L of 25(OH)D.

CONCLUSION

This dose-response meta-analysis suggested a U-shaped relationship between maternal blood 25(OH)D levels and risk of childhood asthma. Further studies are needed to confirm the association.

Can Getting Enough Vitamin D during Pregnancy Reduce the Risk of Getting Asthma in Childhood?

The worldwide increase in asthma prevalence during the last decades and the re-emergence of vitamin D deficiency in many populations hinted toward an underlying association between these two conditions. Since asthma is presented with high incidence in childhood and neonatal vitamin D stores depend on maternal vitamin levels, a possible programming effect of maternal vitamin D status during gestation was suggested. Observational and longitudinal studies on this subject led to inconclusive results with glimmer of positivity. In the randomized controlled clinical trials (RCTs) that followed, increased doses of vitamin D were tested in pregnant women being at high risk of having an asthmatic child. Although, the results of RCTs showed a potential association with asthma-related phenotypes rather than asthma per se, the low toxicity of vitamin D supplements make it tempting to speculate that pregnant women at a high risk of obtaining a child with asthma may be benefited, especially if they are vitamin D deficient.

Associations of maternal and fetal 25-hydroxyvitamin D levels with childhood lung function and asthma: the Generation R Study

BACKGROUND

Exposure to low levels of vitamin D in fetal life might be a risk factor for childhood asthma.

OBJECTIVE

We examined whether 25-hydroxyvitamin D levels in mid-gestation and at birth were associated with higher airway resistance and inflammation, and increased risks of wheezing and asthma in school-age children.

METHODS

We performed a population-based prospective cohort study among 3130 mothers and their children. Maternal blood samples in mid-gestation and umbilical cord blood samples at birth were used to determine 25-hydroxyvitamin D levels. At age of 6, airway resistance (Rint) was measured by interrupter technique and airway inflammation by fractional exhaled nitric oxide (FENO) using NIOX chemiluminescence analyser. Wheezing and asthma were prospectively assessed by annual questionnaires until age 6.

RESULTS

Maternal levels of 25-hydroxyvitamin D in mid-gestation were not associated with Rint, FeNO, wheezing patterns, or asthma. Children in the lowest tertile of 25-hydroxyvitamin D levels at birth had a higher Rint (Z-score (95% confidence interval [95% CI]): -0.42 (-0.84, -0.01), P-value for trend< 0.05), compared to those in the highest tertile group. The effect estimate attenuated when child's current 25-hydroxyvitamin D level was taken into account [Z-score (95% CI): -0.55 (-1.08, 0.01)].

CONCLUSION AND CLINICAL RELEVANCE

Low levels of 25-hydroxyvitamin D at birth were associated with a higher airway resistance in childhood. Additional adjustment for child's current 25-hydroxyvitamin D level reduced the effect size of the association. Further studies are needed to replicate these findings and to examine mechanisms underlying the observed association and the long-term consequences.

In utero exposure to 25-hydroxyvitamin D and risk of childhood asthma, wheeze, and respiratory tract infections: A meta-analysis of birth cohort studies

BACKGROUND

Studies of the associations between in utero 25-hydroxyvitamin D (25[OH]D) exposure and risk of childhood asthma, wheeze, and respiratory tract infections are inconsistent and inconclusive.

OBJECTIVES

We sought to assess associations between 25(OH)D levels in cord blood or maternal venous blood and risk of offspring's asthma, wheeze, and respiratory tract infections.

METHODS

Data were derived from PubMed, Embase, Google Scholar, references from relevant articles, and de novo results from published studies until December 2015. A random-effects meta-analysis was conducted among 16 birth cohort studies.

RESULTS

Comparing the highest with the lowest category of 25(OH)D levels, the pooled odds ratios were 0.84 (95% CI, 0.70-1.01; P = .064) for asthma, 0.77 (95% CI, 0.58-1.03; P = .083) for wheeze, and 0.85 (95% CI, 0.66-1.09; P = .187) for respiratory tract infections. The observed inverse association for wheeze was more pronounced and became statistically significant in the studies that measured 25(OH)D levels in cord blood (0.43; 95% CI, 0.29-0.62; P < .001).

CONCLUSIONS

Accumulated evidence generated from this meta-analysis suggests that increased in utero exposure to 25(OH)D is inversely associated with the risk of asthma and wheeze during childhood. These findings are in keeping with the results of 2 recently published randomized clinical trials of vitamin D supplementation during pregnancy.

A systematic review of early life factors which adversely affect subsequent lung function

It has been known for many years that multiple early life factors can adversely affect lung function and future respiratory health. This is the first systematic review to attempt to analyse all these factors simultaneously. We adhered to strict a priori criteria for inclusion and exclusion of studies. The initial search yielded 29,351 citations of which 208 articles were reviewed in full and 25 were included in the review. This included 6 birth cohorts and 19 longitudinal population studies. The 25 studies reported the effect of 74 childhood factors (on their own or in combinations with other factors) on subsequent lung function reported as percent predicted forced expiration in one second (FEV₁). The childhood factors that were associated with a significant reduction in future FEV₁ could be grouped as: early infection, bronchial hyper-reactivity (BHR) / airway lability, a diagnosis of asthma, wheeze, family history of atopy or asthma, respiratory symptoms and prematurity / low birth weight. A complete mathematical model will only be possible if the raw data from all previous studies is made available. This highlights the need for increased cooperation between researchers and the need for international consensus about the outcome measures for future longitudinal studies.

Prenatal high-dose vitamin D3 supplementation has balanced effects on cord blood Th1 and Th2 responses

Background

Antenatal vitamin D₃ (vitD₃) supplementation significantly increases maternal and neonatal 25-hydroxyvitamin D₃ (25(OH)D₃) concentration, yet the effect of an improvement in maternal-fetal vitamin D status on the neonatal immune response is unclear.

Method

To assess the effect of prenatal vitD₃ supplementation on cord blood T cell function, healthy pregnant Bangladeshi women (n = 160) were randomized to receive either oral 35,000 IU/week vitD₃ or placebo from 26 to 29 weeks of gestation to delivery. In a subset of participants (n = 80), cord blood mononuclear cells (CBMC) were cultured, non-adherent lymphocytes were isolated to assess T cell cytokine responses to phytohemagglutinin (PHA) and anti-CD3/anti-CD28 (iCD3/iCD28), measured by multiplex assay. In 12 participants, lymphocyte gene expression profiles were analyzed by PCR array.

Result

In supplemented group, increased concentrations of IL-10 (P < 0.000) and TNF-α (P = 0.05) with iCD3/iCD28 stimulation and IFN-γ (p = 0.05) with PHA stimulation were obtained compared to placebo group. No differences in the gene expression profile were noted between the two groups. However, PHA stimulation significantly induced the expression of genes encoding Th1 and Th2 cytokines and down-regulated a number of genes involved in T-cell development, proliferation and differentiation of B cells, signal transduction pathway, transcriptional regulation and pattern recognition receptors (PRRs) in the vitamin D group (vitD group).

Conclusion

Third-trimester high-dose vitD₃ supplementation in healthy pregnant women had balanced effects on biomarkers of cord blood Th1 and Th2 responses.

Trial registration

ClinicalTrials.gov (NCT01126528).

Electronic supplementary material

The online version of this article (doi:10.1186/s12937-016-0194-5) contains supplementary material, which is available to authorized users.

Associations of maternal and fetal 25-hydroxyvitamin D levels with childhood eczema: The Generation R Study

BACKGROUND

Exposure to low levels of vitamin D in fetal life might affect the developing immune system, and subsequently the risk of childhood eczema. We examined whether 25-hydroxyvitamin D levels in mid-gestation and at birth were associated with the risk of eczema until the age of 4 years.

METHODS

In a population-based prospective cohort study of 3019 mothers and their children, maternal blood samples in mid-gestation and umbilical cord blood samples at birth were used to determine 25-hydroxyvitamin D levels (severely deficient <25.0 nmol/l, deficient 25.0-49.9 nmol/l, sufficient 50.0-74.9 nmol/l, optimal ≥75.0 nmol/l). Eczema was prospectively assessed by annual questionnaires until the age of 4 years. Eczema patterns included never, early (age ≤1 year only), late (age >1 year only), and persistent eczema (age ≤ and >1 year). Data were assessed using the generalized estimating equations and multinomial regression models.

RESULTS

Compared with the optimal 25-hydroxyvitamin D group, sufficient, deficient, and severely deficient groups of 25-hydroxyvitamin D level in mid-gestation were not associated with the risk of overall eczema (odds ratios [95% confidence interval]: 1.09 [0.82, 1.43], 1.04 [0.87, 1.25], and 0.94 [0.81, 1.10], p-values for trend >0.05), nor with eczema per year or eczema patterns in children up to the age of 4 years. Similarly, we observed no associations of 25-hydroxyvitamin D groups at birth with any eczema outcome.

CONCLUSION

Our results suggest that levels of 25-hydroxyvitamin D in mid-gestation and at birth are not associated with the risk of overall eczema, eczema per year, or eczema patterns among children until the age of 4 years.

The role of vitamin D in atopic dermatitis

Vitamin D has been suggested to have an important impact on a much wider aspects on human health than calcium homeostasis and mineral metabolism, specifically in the field of human immunology. It has been reported that vitamin D influences the regulation of both innate and adaptive immune systems, which makes the association between vitamin D and allergic diseases a field of interest. Although many studies have sought to determine whether vitamin D has an influence on progression of allergic disease, the impact of vitamin D on atopic dermatitis development and severity remains unclear. In this review, we summarize recent studies relating vitamin D to atopic dermatitis and discuss its possible role in the pathogenesis of allergic skin diseases, emphasizing the need for well-designed, prospective trials on vitamin D supplementation in the context of prevention and treatment for allergic conditions.

Maternal and cord blood vitamin D status and childhood infection and allergic disease: a systematic review

CONTEXT

It is unclear how in utero vitamin D deficiency affects the extraskeletal health of children, despite the known risks for adverse pregnancy/birth outcomes.

OBJECTIVE

This systematic review seeks to assess the effect of in utero vitamin D exposure on childhood allergy and infection outcomes using the PRISMA guidelines.

DATA SOURCES

MEDLINE, Cochrane Library, and Web of Science databases were searched.

STUDY SELECTION

Literature published through April 2015 was searched for studies reporting on the association between maternal pregnancy or cord blood vitamin D status and childhood allergy and infection.

DATA EXTRACTION

Of 4175 articles identified, 43 studies met the inclusion criteria. They examined a wide variety of outcomes, using many different vitamin D cutoff values in their analyses.

DATA SYNTHESIS

For most outcomes, results were inconsistent, although there appeared to be a protective effect between higher in utero vitamin D status and childhood lower respiratory tract infection (5 of 10 studies).

CONCLUSIONS

More research is needed on childhood allergy and infection outcomes, and future studies should standardize outcome reporting, especially with regard to cutoff values for vitamin D concentrations. Evidence of a protective association between in utero vitamin D exposure and lower respiratory tract infection was found, while the other outcomes were either understudied or showed inconsistent results.PROSPERO registration no. CRD42013006156.

Vitamin D in atopic dermatitis, chronic urticaria and allergic contact dermatitis

Vitamin D influences allergen-induced pathways in the innate and adaptive immune system, and its potential immunomodulatory role in allergic skin disorders has been explored. This comprehensive review article provides an overview of the role of vitamin D in three common dermatologic conditions: atopic dermatitis (AD), chronic urticaria, and allergic contact dermatitis (ACD). Whereas the literature regarding vitamin D and AD has resulted in mixed findings, several studies have described an inverse relationship between vitamin D levels and AD severity, and improvement in AD with vitamin D supplementation. Similarly, several studies report an inverse relationship between vitamin D levels and severity of chronic urticaria. Although current research in humans remains limited, an increased likelihood of ACD has been demonstrated in vitamin D-deficient mice. Additional well-designed clinical trials will be necessary to determine whether vitamin D supplementation should be recommended for prevention or adjuvant treatment of these common dermatologic conditions.

Essential vitamins for an effective T cell response

Effective adaptive immune responses rely upon appropriate activation of T cells by antigenic peptide-major histocompatibility complex on the surface of antigen presenting cells (APCs). Activation relies on additional signals including co-stimulatory molecules on the surface of the APCs that promote T cell expansion. The immune response is further sculpted by the cytokine environment. However, T cells also respond to other environmental signals including hormones, neurotransmitters, and vitamins. In this review, we summarize the mechanisms through which vitamins A and D impact immune responses, particularly in the context of T cell responses.

Vitamin D and asthma: current perspectives

PURPOSE OF REVIEW

To review the current evidence on the relationship between vitamin D and asthma.

RECENT FINDINGS

The rising morbidity and tremendous socioeconomic burden of asthma have prompted efforts to seek modifiable environmental and nutritional factors that contribute to the asthma epidemic. The association between low levels of vitamin D and asthma has been supported by many, but not all observational and epidemiologic studies. Recently, several controlled clinical trials have been undertaken to explore the effect of vitamin D supplementation on asthma control and respiratory tract infections. While some trials support the beneficial role of vitamin D supplementation in reducing asthma severity in children, several trials have found no beneficial role in adults.

SUMMARY

Given the high prevalence of vitamin D insufficiency in children and adults worldwide and recent randomized controlled trials of vitamin D in asthma, supplementation with vitamin D cannot be recommended as adjunctive therapy for asthma.

Effects of Pre-Natal Vitamin D Supplementation with Partial Correction of Vitamin D Deficiency on Early Life Healthcare Utilisation: A Randomised Controlled Trial

Background

Some observational studies have suggested that higher prenatal Vitamin D intake may be associated with improved health outcomes in childhood. However there have been mixed results in this area with some negative studies, especially for effects on atopic and respiratory outcomes. We examined the effect of prenatal Vitamin D on healthcare utilisation in the first three years of life.

Methods

In an ethnically stratified randomised controlled trial conducted at St Mary’s Hospital London, 180 women at 27 weeks gestation were allocated to no Vitamin D, 800 IU ergocalciferol daily until delivery, or a single oral bolus of 200,000 IU cholecalciferol. Participants were randomised in blocks of 15 using computer-generated numbers and investigators were blinded to group assignment. Supplementation increased maternal and cord blood 25(OH) vitamin D concentrations, but levels remained lower than current recommendations. Primary health economic outcome was overall cost of unscheduled healthcare utilisation in the first three years of life as documented in the child’s electronic health record. Secondary outcomes included cost attributable to: primary and secondary healthcare visits, respiratory and atopic complaints, cost in years 1, 2 and 3 of life and cost and frequency of prescribed medication. All costs were calculated as pounds sterling. Differences between groups were analysed using unpaired t-test or Mann-Whitney U test, and analysis of variance for adjusted analyses.

Results

We assessed 99/180 (55%) complete electronic health records, control (n = 31), daily (n = 36) and bolus (n = 32). We found no difference in total healthcare utilisation costs between the control and daily (mean difference in costs in pounds sterling 1.02, 95%CI -1.60, 1.65; adjusted 1.07, 95%CI -1.62, 1.86) or control and bolus groups (mean difference -1.58, 95%CI -2.63, 1.06; adjusted –1.40, 95%CI -2.45, 1.24). There were no adverse effects of supplementation reported during the trial.

Conclusions

We found no evidence that prenatal vitamin D supplementation from 27 weeks gestation to delivery, at doses which failed to completely correct maternal vitamin D deficiency, influence overall healthcare utilisation in children in the first 3 years.

Trial Registration

Controlled-Trials.com ISRCTN68645785

Vitamin D and the development of allergic disease: how important is it?

Vitamin D has known effects on lung development and the immune system that may be important in the development, severity, and course of allergic diseases (asthma, eczema, and food allergy). Vitamin D deficiency is prevalent worldwide and may partly explain the increases in asthma and allergic diseases that have occurred over the last 50-60 years. In this review, we explore past and current knowledge on the effect of vitamin D on lung development and immunomodulation and present the evidence of its role in allergic conditions. While there is growing observational and experimental evidence for the role of vitamin D, well-designed and well-powered clinical trials are needed to determine whether supplementation of vitamin D should be recommended in these disorders.

Maternal diet and its influence on the development of allergic disease

The early presentation of childhood allergies and the rise in their prevalence suggest that changes in early-life exposures may increase the predisposition. Very early-life exposures may act upon the developing foetal immune system and include infection, environmental tobacco smoke, other pollutants and nutrients provided via the mother. Three nutrients have come under close scrutiny: vitamin D, omega 3 polyunsaturated fatty acids (PUFAs) and folate (or the synthetic form, folic acid). Much of the data on these nutrients are observational although some randomised, placebo-controlled trials have been conducted with omega 3 PUFAs and one with vitamin D. Some studies with omega 3 PUFA supplements in pregnancy have demonstrated immunomodulatory effects on the neonate and a reduction in risk of early sensitisation to allergens. A few studies with omega 3 polyunsaturated fatty acid supplements in pregnancy have shown a reduction in proportion of children affected by allergic symptoms (food allergy) or in symptom severity (atopic dermatitis). Observational studies investigating the association of maternal vitamin D intake or maternal or neonatal vitamin D status have been inconsistent. One randomised, controlled trial of vitamin D supplementation during pregnancy did not show any significant effect on allergic outcome in the offspring. Studies investigating the association between maternal folic acid or folate intake or maternal or neonatal folate status and offspring risk of allergic disease have been equivocal. Further evidence is required to clarify whether increased intake of these nutrients during pregnancy influences allergic disease in the offspring. In the light of current evidence, mothers should not either increase or avoid consuming these nutrients to prevent or ameliorate allergic disease in their offspring. However, these essential nutrients each have important roles in foetal development. This is reflected in current government recommendations for intake of these nutrients by pregnant women.

Developments in the field of allergy in 2013 through the eyes of Clinical and Experimental Allergy

2013 was another exciting year for allergy in general and Clinical and Experimental Allergy in particular. In the field of asthma and rhinitis, there continued to be a focus on heterogeneity and phenotypes with increasing use of biostatistical techniques to determine clusters of similar populations. Obesity- and aspirin-associated disease are intriguing associations with asthma which were explored in a number of papers. We published a number of excellent papers on mechanisms of airway inflammation and how this relates to physiology, pathology, genetics and biomarkers in both human and experimental model systems. In terms of mechanisms, there is less on individual cell types in allergic disease at the moment, but the immunology of allergic disease continued to fascinate our authors. Another area that was popular both in the mechanisms and in the epidemiology sections was early life events and how these lead to allergic disease, with an increasing focus on the role of the microbiome and how this influences immune tolerance. In the clinical allergy section, oral immunotherapy for food allergy is clearly a major topic of interest at the moment as was in vitro testing to distinguish between sensitization and allergic disease. There was less on inhalant allergy this year, but a good representation from the drug allergy community including some interesting work on non-IgE-mediated mechanisms. In the allergen section, important new allergens continue to be discovered, but the major focus as in the last couple of years was on working out how component-resolved approaches can improve diagnosis and management of food and venom allergy.

Association between vitamin D levels and allergy-related outcomes vary by race and other factors

BACKGROUND

Allergy-related studies that include biological measurements of vitamin D preceding well-measured outcomes are needed.

OBJECTIVE

We sought to examine the associations between early-life vitamin D levels and the development of allergy-related outcomes in the racially diverse Wayne County Health, Environment, Allergy, and Asthma Longitudinal Study birth cohort.

METHODS

25-Hydroxyvitamin D (25[OH]D) levels were measured in stored blood samples from pregnancy, cord blood, and age 2 years. Logistic regression models were used to calculate odds ratios (ORs) with 95% CIs for a 5 ng/mL increase in 25(OH)D levels for the following outcomes at age 2 years: eczema, skin prick tests (SPTs), increased allergen-specific IgE level (≥ 0.35 IU/mL), and doctor's diagnosis of asthma (3-6 years).

RESULTS

Prenatal 25(OH)D levels were inversely associated with eczema (OR, 0.85; 95% CI, 0.75-0.96). The association was stronger in white children (white children: OR, 0.79; 95% CI, 0.57-1.09; black children: OR, 0.96; 95% CI, 0.82-1.12), although this was not statistically significant. Cord blood 25(OH)D levels were inversely associated with having 1 or more positive SPT responses and aeroallergen sensitization. Both associations were statistically significant in white children (positive SPT response: OR, 0.50; 95% CI, 0.32-0.80; ≥ 1 aeroallergen sensitization: OR, 0.50; 95% CI, 0.28-0.92) in contrast with black children (positive SPT response: OR, 0.88; 95% CI, 0.68-1.14; ≥ 1 aeroallergen sensitization: OR, 0.85; 95% CI, 0.65-1.11). 25(OH)D levels measured concurrently with outcome assessment were inversely associated with aeroallergen sensitization (OR, 0.79; 95% CI, 0.66-0.96) only among black children (white children: OR, 1.21; 95% CI, 0.87-1.69).

CONCLUSIONS

Prenatal and cord blood 25(OH)D levels were associated with some allergy-related outcomes, with a general pattern indicating that children with higher 25(OH)D levels tend to have fewer allergy-related outcomes.

Vitamin D and the Development of Atopic Eczema

A “vitamin D hypothesis” has been proposed to explain the increased prevalence of eczema in regions with higher latitude. This review focuses on the current available evidence with regard to the possible effect of vitamin D on the development of atopic eczema. Observational studies have indicated a link between vitamin D status and eczema outcomes, including lower serum vitamin D levels associated with increased incidence and severity of eczema symptoms. Vitamin D is known to have a regulatory influence on both the immune system and skin barrier function, both critical in the pathogenesis of eczema. However heterogeneous results have been found in studies to date investigating the effect of vitamin D status during pregnancy and infancy on the prevention of eczema outcomes. Well-designed, adequately powered, randomised controlled trials are needed. The study design of any new intervention trials should measure vitamin D levels at multiple time points during the intervention, ultraviolet (UV) radiation exposure via the use of individual UV dosimeters, and investigate the role of individual genetic polymorphisms. In conclusion, the current available evidence does not allow firm conclusions to be made on whether vitamin D status affects the development of atopic eczema.

The role of circulating 25 hydroxyvitamin D in asthma: a systematic review

Asthma is a major public health issue. The co-occurrence of the high prevalence of asthma and vitamin D deficiency documented globally in recent decades has prompted several investigations into a possible association between the two conditions. The objective of this paper was to synthesize the evidence from studies that have measured the association between serum vitamin D and asthma incidence, prevalence, severity and exacerbations. A systematic search of the literature was performed in PubMed, and the available evidence was summarized both qualitatively and by meta-analysis. Only English language, observational studies measuring serum levels of 25(OH)D as the exposure were included, as this is the most robust measure of vitamin D levels. The search identified 23 manuscripts: two case-control, 12 cohort and nine cross-sectional studies. Collectively, the evidence suggests that higher serum levels of 25(OH)D are associated with a reduced risk of asthma exacerbations, but there was little evidence to suggest an association with asthma incidence, prevalence or severity. A significant amount of heterogeneity between study methodology and results restricted the scope for meta-analysis. These results suggest that vitamin D supplementation may be effective for the prevention of asthma exacerbations, but the findings need to be confirmed by clinical trials.

The role of the early-life environment in the development of allergic disease

A consensus has been reached that the development of allergic disorders is strongly influenced by early life exposures. An overview of several prenatal and early life factors that have been investigated for their associations with development of childhood allergy is presented. Delivery mode, the gut microbiome, vitamin D, folate, breastfeeding, pets, antibiotics, environmental tobacco smoke, and airborne traffic pollutants are discussed. Although many studies suggest an effect, overall, no risk factors clearly increase or reduce the risk of allergic outcomes.

The long-term programming effect of maternal 25-hydroxyvitamin D in pregnancy on allergic airway disease and lung function in offspring after 20 to 25 years of follow-up

BACKGROUND

High prenatal vitamin D status has been linked to decreased risk of atopic diseases in early childhood, but whether such relations persist until adulthood has not been explored.

OBJECTIVE

We sought to examine the association between maternal 25-hydryxovitamin D (25[OH]D) concentrations and outcomes of allergic airway disease and lung function in offspring with 20 to 25 years of follow-up.

METHODS

In a prospective birth cohort with 965 pregnant women enrolled in 1988-1989, maternal 25(OH)D concentrations were quantified in serum from gestational week 30 (n = 850 [88%]). Offspring were followed in nationwide registries with complete follow-up to the age of 25 years (n = 850 [100%]). Additionally, at age 20 years, outcomes of allergic airway disease and lung function were assessed in a subset of offspring by using blood samples and spirometry (n = 410 [45%]) and a questionnaire (n = 641 [70%]).

RESULTS

Exposure to a high maternal 25(OH)D concentration (≥125 nmol/L) was associated with an increased risk of asthma hospitalizations in offspring (hazard ratio [HR], 1.81; 95% CI, 0.78-4.16) during 25 years of follow-up compared with the reference group (75-<125 nmol/L). Furthermore, there were lower risks of asthma hospitalizations (HR, 0.29; 95% CI, 0.08-1.02) and asthma medication use (HR, 0.58; 95% CI, 0.35-0.95) in those exposed to a low maternal 25(OH)D concentration (<50 nmol/L). In a reduced set of participants, we found no associations between maternal 25(OH)D concentrations and offspring allergen-specific IgE, total IgE, and eosinophil cationic protein levels; self-reported doctor's diagnosis of asthma or hay fever; or lung function at 20 years of age.

CONCLUSIONS

Our study does not provide support for a protective effect of a high maternal 25(OH)D concentration on outcomes of allergic airway disease and lung function at 20 to 25 years of age. In contrast, a high maternal 25(OH)D concentration might be associated with an increased risk of allergic diseases in offspring.

Predicted vitamin D status in mid-pregnancy and child allergic disease

BACKGROUND

Vitamin D deficiency in pregnancy may be a risk factor for child allergic disease. However, less is known about disease risk across different levels of vitamin D.

OBJECTIVE

We aimed to examine the relation between a maternal vitamin D prediction score and child allergic disease.

METHODS

A total of 32,456 pregnant women were enrolled in the Danish National Birth Cohort (1996-2003) and had data on a validated vitamin D prediction score based on 1497 mid-pregnancy plasma 25(OH)D samples. Child allergic disease was assessed at 18 months and at 7 years using questionnaire data and national registry extracts. We used multivariable log-binomial models to quantify risk ratios (RR) and 95% CI. Plasma 25(OH)D was examined in a stability analysis.

RESULTS

Median (IQR) vitamin D prediction score was 58.7 (49.2-69.0) nmol/l. In main analysis, there was no association between vitamin D prediction score examined in quintiles or by restricted categories (≥75 nmol/l and <25 nmol/l vs. 25-74.9 nmol/l) and child allergic disease. However, maternal vitamin D prediction score ≥100 nmol/l(vs. 50-79.9 nmol/l) was associated with increased risks of child asthma at 18 months (RR: 1.36, 95% CI: 1.02, 1.80) and asthma by hospital admission (RR: 1.65, 95% CI: 1.04, 2.62). For vitamin D prediction score <25-30 nmol/l, there were increased risks of child asthma at 18 months and by hospital admission and medication prescription at age 7, although these findings were not robust to covariate adjustment. Similar results were found for plasma 25(OH)D.

CONCLUSIONS

Our study provided little evidence for an association between maternal vitamin D prediction score and child allergic disease for scores ≥75 nmol/l. However, increased risks were observed for vitamin D prediction score ≥100 nmol/l. These associations are hypothesis generating and would need to be replicated in other cohorts.

Maternal vitamin D and E intakes during pregnancy are associated with asthma in children

Are maternal vitamin D and E intakes during pregnancy associated with asthma in 10-year-old children? In a longitudinal study of 1924 children born to women recruited during pregnancy, maternal vitamin D intake during pregnancy was assessed by the Food Frequency Questionnaire (FFQ) and vitamin E by FFQ and plasma α-tocopherol; respiratory questionnaires were completed for the 10-year-old children. Their treatment for asthma was also ascertained using administrative data. Longitudinal analyses included data collected at 1, 2, 5 and 10 years. Symptom data were available for 934 (49%) children and use of asthma medication for 1748 (91%). In the children maternal vitamin D intake during pregnancy was negatively associated with doctor-diagnosed asthma at 10 years of age (OR per intake quintile 0.86, 95% CI 0.74-0.99) and over the first 10 years (hazard ratio 0.90, 95% CI 0.81-1.00). Maternal plasma α-tocopherol at 11 weeks gestation was negatively associated with children receiving asthma treatment (OR per standard deviation increase 0.52, 95% CI 0.31-0.87). Maternal vitamin E intake was negatively associated with doctor-diagnosed asthma (OR 0.89, 95% CI 0.81-0.99) in the first 10 years. Low maternal vitamin D and E intakes during pregnancy are associated with increased risk of children developing asthma in the first 10 years of life. These associations may have significant public health implications.

Epigenomics and allergic disease

Allergic disease development is affected by both genes and the environment, and epigenetic mechanisms are hypothesized to mediate these environmental effects. In this article, we discuss the link between the environment, DNA methylation and allergic disease, as well as questions of causality inherent to analyses of DNA methylation. From the practical side, we describe characteristics of allergic phenotypes and contrast different epidemiologic study designs used in epigenetic research. We examine methodological considerations, how best to conduct preprocessing and analysis of DNA methylation data sets, and the latest methods, technologies and discoveries in this rapidly advancing field. DNA methylation and other epigenetic marks are firmly entwined with allergic disease, a link that may hold the basis for future allergic disease diagnosis and treatment.

Early-life origins of chronic respiratory diseases: understanding and promoting healthy ageing

Chronic obstructive respiratory disorders such as asthma and chronic obstructive pulmonary disease often originate early in life. In addition to a genetic predisposition, prenatal and early-life environmental exposures have a persistent impact on respiratory health. Acting during a critical phase of lung development, these factors may change lung structure and metabolism, and may induce maladaptive responses to harmful agents, which will affect the whole lifespan. Some environmental factors, such as exposure to cigarette smoke, type of childbirth and diet, may be modifiable, but it is more difficult to influence other factors, such as preterm birth and early exposure to viruses or allergens. Here, we bring together recent literature to analyse the critical aspects involved in the early stages of lung development, going back to prenatal and perinatal events, and we discuss the mechanisms by which noxious factors encountered early on may have a lifelong impact on respiratory health. We briefly comment on the need for early disease biomarkers and on the possible role of "-omic" technologies in identifying risk profiles predictive of chronic respiratory conditions. Such profiles could guide the ideation of effective preventive strategies and/or targeted early lifestyle or therapeutic interventions.