Neonatal vitamin D status and childhood peanut allergy: a pilot study

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.

Association of food allergy in children with vitamin D insufficiency: a systematic review and meta-analysis

Current literature regarding the association of vitamin D insufficiency and food allergy is contradicting. The purpose of our study was to investigate this association. This is a systematic review and meta-analysis according to the PRISMA statement. PubMeD and Scopus databases were systematically searched for case-control studies investigating the association between pediatric food allergy and vitamin D insufficiency. Our search yielded 806 studies. Ten final studies were considered eligible for qualitative and quantitative analysis. Children with vitamin D insufficiency were found to have 68% more probability to present a food allergy episode (adjusted pooled OR: 1.68, 95% CI [1.25-2.27], p-value: 0.001). In their second year of life they were 4 times more likely to present a food allergy episode (adjusted pooled OR: 4.06, 95% CI [1.93-8.56], p-value: < 0.001), and 56% more probable to develop food sensitization (OR: 1.56, 95% CI [1.15-2.11], p-value: < 0.004). Children in Australia with vitamin D insufficiency were almost 4 times more likely to develop egg sensitization (adjusted OR: 3.79, 95% CI [1.19-12.08], p-value: 0.024). Children with vitamin D insufficiency were almost twice as likely to have peanut sensitization (OR: 1.96, 95% CI [1.08-3.57], p-value: 0.028).  Conclusion: Decreased maternal vitamin D levels and infant vitamin D insufficiency appear to increase the incidence of food allergies, particularly in the second year of life. To confirm this association, multicenter longitudinal studies are required. What is Known: • In newborns and young children, vitamin D deficiency and insufficiency are prevalent. • The exact role of vitamin D in atopic diseases remains controversial. What is New: • Decreased maternal vitamin D levels and infant vitamin D insufficiency appear to increase the incidence of food allergies. This association is more evident in the second year of life.

Epidemiological survey of self-reported food allergy among university students in China

The aim of this study was to investigate the prevalence of self-reported food allergy among university students in China. A cluster-random sampling population-based cross-sectional study using self - administrated questionnaire was conducted with 2538 college students recruited from 6 universities in China. The questionnaire included data on age, sex, weight, height, FA, comorbid allergic diseases, family history, and understanding food allergy. Data were analyzed by SPSS 25.0 statistical software. Multivariate logistic regression analysis was performed to analyze the risk factors related to self-reported food allergy and estimate the odds ratio. A total of 2538 questionnaires were distributed to the undergraduate students and 2313 completely effective questionnaires were collected, the effective response rate was 91.1%. 834 males and 1479 females were recruited, and their age ranged from 18 to 25 years old. The prevalence of self-reported food allergy was 15.7%, and the rate of doctor-diagnosed food allergy was 8.4%. The leading food allergens included shrimp, shellfish, milk, egg, peach, mango, beef, and peanut, and the prevalence of shrimp allergy was the highest (5.8%). The main clinical manifestation included skin mucous membrane and respiratory symptoms. The prevalence of food allergy were statistically significant difference (P < .05) between different age groups, family history, sun exposure times, smoking, and antibiotic use. Over 45% college students know little about food allergy. The prevalence of self-reported food allergy among Chinese college students was high (15.7%). Shrimp was the main allergenic food, followed by shellfish, milk, egg, peach, and mango. Family history, sun exposure, obesity, and using antibiotics may be the influencing factors of food allergy. The Chinese undergraduates lacked the knowledge about food allergy. Thus, it is necessary to strengthen the health education program on food allergy for college students in China and other middle high-income nations.

Cord blood 25(OH)D3, cord blood total immunoglobulin E levels, and food allergies in infancy: A birth cohort study in Chongqing, China

Background

Food allergy (FA) in infants has become a common disease worldwide. There are many controversies surrounding the relationships among levels of cord blood 25-hydroxy vitamin D3 [25(OH)D3], total immunoglobulin E (IgE), and FA.

Methods

In this study, we recruited pregnant women in the third trimester undergoing obstetric examination in Chongqing City, Western China. Healthy full-term singleton births between May to August 2018 and November 2018 to January 2019 were included in the summer-birth and winter-birth cohorts, respectively. Questionnaires on vitamin D status in pregnancy and family allergies were used to investigate the pregnant women. The levels of <12 ng/mL, 12～20 ng/mL, and >20 ng/mL 25(OH)D3 in cord blood detected by liquid chromatography tandem mass spectrometry were considered deficient, insufficient, and sufficient, respectively. The electrochemiluminescence method was used to detect the total lgE levels in cord blood, classified into low-IgE (<0.35 IU/mL) and high-IgE (≥0.35 IU/mL) levels, respectively. Within postnatal 6 months, allergic symptoms in infants were investigated using questionnaire during the infants' monthly physical examinations. Suspected cases of FA underwent a history inquiry, skin prick test, food elimination test, and open-food challenge for diagnosis of FA. Multivariate logistic regression was used to analyze the risk factors of FA in infants.

Results

In this study, we recruited 741 pairs of pregnant women and infants, including 343 infants in the summer-birth cohort and 398 infants in the winter-birth cohort. The incidence of FA within postnatal 6 months was 6.88%, showing significantly higher incidence of FA in the winter-birth cohorts than in the summer-birth cohorts (10.3% vs. 2.9%, χ2 = 15.682, P = 0.000). Among the 741 infants, 47.1%, 27.5%, and 13.8% of infants had deficient, insufficient, and sufficient 25(OH)D3, respectively, in the cord blood; 81.5% and 18.5% of infants had total low-IgE and total high-IgE levels, respectively, in the cord blood. No significant correlation was found between the 25(OH)D3 and IgE levels (r = -0.038, P = 0.300). Logistic regression analysis showed that winter birth [odds ratio (OR) 95% confidence interval (CI): 4.292 (2.003～8.359)] compared with infants in summer birth group, and sufficient (>20 ng/mL) 25(OH)D3 levels in cord blood [OR (95% CI): 2.355 (1.129～4.911) compared with infants in the deficient group (<12 ng/mL) and 3.782 (1.680～8.514) compared with infants in the insufficient group (12～20 ng/mL)] were independent risk factors for FA in infants within postnatal 6 months.

Conclusions

Winter birth and sufficient 25(OH)D3 levels in infant cord blood were independent risk factors for FA in infants. 25(OH)D3 and total IgE levels in cord blood cannot be used as predictors of FA in early infancy.

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.

Role of Vitamin D in Prevention of Food Allergy in Infants

The prevalence of food allergy is increasing over the last decades. The role of vitamin D in the prevention of food allergy has been largely investigated. Its role on the physiology of calcium and bone is known, but calcitriol (active form of the vitamin D) also influences the epithelial cells, T cells, B cells, macrophages, and dendritic cells. Almost all cells of the adaptive immune system express the vitamin D receptor, making them also capable of being vitamin responsive. Specifically considering the potential role of vitamins in food allergy, vitamin D has been shown to affect several mechanisms that promote immunologic tolerance, including the T regulatory cell function and the induction of tolerogenic dendritic cells. The target of our review is to evaluate the role of vitamin D in the prevention of food allergy in children. There are contradictory data on the relationship among the vitamin D deficiency and the developing of food allergy. Some studies associate lower exposure to sunlight to food allergy; on the other hand, further research has found that higher vitamin D levels could increase the likelihood of allergic sensitization and food allergy. Therefore, there is an urgent need for well-planned randomized controlled trials on vitamin D supplementation, with particular regard to the prevention of food allergy. The role of vitamin D beyond bone and calcium metabolism is not fully understood.

Mechanisms of gastrointestinal allergic disorders

Gastrointestinal (GI) allergic disease is an umbrella term used to describe a variety of adverse, food antigen-driven, immune-mediated diseases. Although these diseases vary mechanistically, common elements include a breakdown of immunologic tolerance, a biased type 2 immune response, and an impaired mucosal barrier. These pathways are influenced by diverse factors such as diet, infections, exposure to antibiotics and chemicals, GI microbiome composition, and genetic and epigenetic elements. Early childhood has emerged as a critical period when these factors have a dramatic impact on shaping the immune system and therefore triggering or protecting against the onset of GI allergic diseases. In this Review, we will discuss the latest findings on the molecular and cellular mechanisms that govern GI allergic diseases and how these findings have set the stage for emerging preventative and treatment strategies.

Role of dendritic cells in peanut allergy

INTRODUCTION

The prevalence of peanut allergy (PA) has increased, affecting approximately 1.1% of children in Western countries. PA causes life-threatening anaphylaxis and frequently persists for life. There are no standardized curative therapies for PA, and avoidance of peanuts remains the main therapeutic option. A better understanding of the pathogenesis of PA is essential to identify new treatment strategies. Intestinal dendritic cells (DCs) are essential in the induction and maintenance of food tolerance because they present dietary allergens to T cells, thereby directing subsequent immune responses. Areas covered: In this review, we discuss the factors related to the acquisition of oral tolerance to peanut proteins. We focus on intestinal DC-related aspects, including the latest advances in the biology of intestinal DC subtypes, effect of tolerance-inducing factors on DCs, effect of dietary components on oral tolerance, and role of DCs in peanut sensitization. Expert commentary: Given the increasing prevalence of PA, difficulty of avoiding peanut products, and the potentially serious accidental reactions, the development of novel therapies for PA is needed. The ability of DCs to trigger tolerance or immunity makes them an interesting target for new treatment strategies against PA.

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.

Correlation between serum vitamin D status and immunological changes in children affected by gastrointestinal food allergy

BACKGROUND

Low vitamin D status is linked to increased incidence of food allergy and intestinal inflammation. Whether vitamin D status is associated with immunological changes in children with gastrointestinal food allergy (GFA) remains unclear.

METHODS

Forty-nine GFA children (aged 2-11 years old) were enrolled in this study. Serum 25-hydroxyvitamin D (25OHD) level, total immunoglobulin E (IgE), specific IgE against allergens, circulating regulatory T lymphocytes (Tregs), and blood eosinophil numbers were measured.

RESULTS

Levels of serum 25OHD in the GFA children ranged 35.5-156.4nmol/L, with a mean value similar to that of the healthy controls. Compared to those with normal 25OHD (≥75nmol/L), GFA children with low 25OHD (<75nmol/L) had increased total IgE (84% vs. 54%, P<0.05), persistent blood eosinophilia (56% vs. 25%, P<0.05), and delayed resolution of symptoms after food allergen elimination (odds ratio 3.51, 95% CI 1.00-12.36, P<0.05). Among the GFA children with elevated total IgE, those with low 25OHD had lower circulatory Tregs (8.79±2.4% vs. 10.21±1.37%, P<0.05), higher total IgE (1197.5±1209.8 vs. 418.5±304.6kU/L, P<0.05), and persistent eosinophilia (0.61±0.52 vs. 0.31±0.15×10⁹cells/L, P<0.05) compared to those with normal 25OHD. In addition, serum 25OHD concentrations inversely correlated with total IgE (R=-0.434, P<0.05), and positively with Treg population (R=0.356, P<0.05).

CONCLUSION

Low serum vitamin D status correlates with stronger allergic immune response in GFA children.

Primary Prevention of Food Allergy

PURPOSE OF REVIEW

This article summarises recent developments on the prevention of food allergy in terms of the 5 D's of the development of food allergy: dry skin, diet, dogs, dribble, and vitamin D.

RECENT FINDINGS

While several advances have improved our understanding of the development of food allergy, few preventive strategies have been implemented beyond changes in infant feeding guidelines. These now state that the introduction of allergenic solids such as peanuts should occur in the first year of life. Results from randomised controlled trials on other allergenic solids, vitamin D supplementation, BCG immunisation at birth and eczema prevention are eagerly anticipated in order to inform further preventative strategies.

Vitamin D insufficiency in the first 6 months of infancy and challenge-proven IgE-mediated food allergy at 1 year of age: a case-cohort study

BACKGROUND

Ecological evidence suggests vitamin D insufficiency (VDI) due to lower ambient ultraviolet radiation (UVR) exposure may be a risk factor for IgE-mediated food allergy. However, there are no studies relating directly measured VDI during early infancy to subsequent challenge-proven food allergy.

OBJECTIVE

To prospectively investigate the association between VDI during infancy and challenge-proven food allergy at 1 year.

METHODS

In a birth cohort (n = 1074), we used a case-cohort design to compare 25-hydroxyvitamin D₃ (25(OH)D₃ ) levels among infants with food allergy vs a random subcohort (n = 274). The primary exposures were VDI (25(OH)D₃ <50 nM) at birth and 6 months of age. Ambient UVR and time in the sun were combined to estimate UVR exposure dose. IgE-mediated food allergy status at 1 year was determined by formal challenge. Binomial regression was used to examine associations between VDI, UVR exposure dose and food allergy and investigate potential confounding.

RESULTS

Within the random subcohort, VDI was present in 45% (105/233) of newborns and 24% (55/227) of infants at 6 months. Food allergy prevalence at 1 year was 7.7% (61/786), and 6.5% (53/808) were egg-allergic. There was no evidence of an association between VDI at either birth (aRR 1.25, 95% CI 0.70-2.22) or 6 months (aRR 0.93, 95% CI 0.41-2.14) and food allergy at 1 year.

CONCLUSIONS

There was no evidence that VDI during the first 6 months of infancy is a risk factor for food allergy at 1 year of age. These findings primarily relate to egg allergy, and larger studies are required.

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.

Minimizing Matrix Effects for the Accurate Quantification of 25-Hydroxyvitamin D Metabolites in Dried Blood Spots by LC-MS/MS

BACKGROUND

The noncalcemic actions of vitamin D in multiple organs are now widely recognized. Vitamin D status has been linked with a wide variety of conditions, which has led to an increasing demand for vitamin D screening. In particular, there is intense interest in the impact of vitamin D on a variety of developmental conditions. The most readily accessible pediatric samples are dried blood spots, and health organizations are increasingly archiving such samples for later assessment of the antecedents of disease.

METHODS

In 2009, we developed a method to quantify the major circulatory form of vitamin D, 25-hydroxyvitamin D, in archived dried blood spots. Over the last 6 years, we have made substantial alterations to the published method to enhance throughput, sensitivity, and assay robustness.

RESULTS

With the alterations, the assay was 3 times faster than the previously published assay and had a &gt;10-fold increase in signal strength. Intraassay imprecision decreased from 13.4% to 6.9%, and there was a 5-fold reduction in interfering phospholipids. In actual use over 2 years, the assay showed an interassay imprecision of 11.6%.

CONCLUSIONS

This assay has performed reliably over the past 6 years. The practical changes we have made should allow clinical chemists to successfully adapt this method.

Sunlight, vitamin D and food allergy

PURPOSE OF REVIEW

The role of vitamin D in the development of food allergy is unclear. We summarize recent data on the epidemiologic link between sunlight (UVB) and food allergy, and evidence for and against a specific role for vitamin D status.

RECENT FINDINGS

Since 2007, most epidemiologic studies have supported low sunlight (as measured by season of birth and latitude) as a risk factor for food allergy. Investigators have also looked directly at vitamin D status (as measured by serum 25OHD level) and its potential role. Although conflicting, the vitamin D studies suggest a more complicated association than a linear dose response in all individuals, with some studies indicating different associations based on host characteristics (e.g. concominant eczema, genetic polymorphisms, country of birth). Most studies have not fully examined the myriad effects of sunlight but have instead focused on a single maternal, neonatal or childhood 25OHD level.

SUMMARY

Many studies have linked sunlight with the development of food allergy but whether this is directly related to vitamin D status or a myriad of other sunlight-derived, seasonal and/or geographic factors remains uncertain. More studies are needed to investigate the role of sunlight and vitamin D status in food allergy because of their potential for primary prevention and disease modification.

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.

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.

Food allergy: the perspectives of prevention using vitamin D

PURPOSE OF REVIEW

We reviewed the scientific publications in the last 2 years on the connections between vitamin D and food allergy, and endeavor to focus on the possible indications for supplementation in order to prevent allergies.

RECENT FINDINGS

Ecological studies have suggested a possible relationship between sun exposure and atopic diseases such as asthma, atopic dermatitis and anaphylaxis. However, no direct evaluation of vitamin D status has been performed. Recent studies evaluating the relationship with vitamin D levels at birth or during pregnancy have shown conflicting results with the lower levels of vitamin D associated with eczema, the higher with increased food allergy prevalence.

SUMMARY

Although the role of vitamin D in extraskeletal function is certainly intriguing and must not be underestimated, at the moment there is a lack of consistent data addressing the topic of vitamin D supplementation in the prevention of food allergies. However, in light of the vast amount of literature regarding the mechanisms connected with atopic diseases, an evaluation of serum levels of vitamin D and eventually supplementation must be considered as a further opportunity to understand and treat atopic diseases. In this regard, well designed trials on vitamin D supplementation to prevent food allergies are urgently needed.

Associations between serum folate and vitamin D levels and incident mouse sensitization in adults

BACKGROUND

Although both folic acid intake and vitamin D levels are hypothesized to be contributors to the increased incidence of allergic diseases, prospective studies of these relationships have not been done in adults.

OBJECTIVES

We sought to determine whether serum folate or vitamin D levels are associated with incident mouse sensitization among new workers at a mouse facility.

METHODS

Subjects started employment at the Jackson Laboratory between June 2004 and July 2007. Skin testing to mouse and other allergens and collection of questionnaire data were performed at baseline and every 6 months. Serum folate and vitamin D levels were assessed on baseline samples stored at -80°C. Folate was categorized into tertiles (2.5-10.5, 10.5-16.2, and 16.2-78.4 ng/mL, respectively). Vitamin D was categorized as less than 20 ng/mL, 20 to 29 ng/mL, or 30 ng/mL or greater. This was a nested case-control study in which 5 control subjects were matched to each case on baseline atopy and type of employment. Multivariate analyses controlled for age, sex, education, smoking, season, personal mouse exposure, and serum folate and vitamin D levels.

RESULTS

Thirty-five cases and 47 control subjects were included. The odds of incident mouse sensitization were higher in the intermediate and highest tertiles of serum folate compared with the lowest tertile of serum folate (odds ratio of 10.5 [95% CI, 1.8-61.5; P = .009] and odds ratio of 5.6 [95% CI, 1.8-31.3; P = .049], respectively, in the multivariate model). Serum vitamin D levels were not associated with incident mouse sensitization.

CONCLUSIONS

These findings support a role for higher serum folate levels in increased risk of incident allergic disease, even during adulthood.