Vitamin D and Its Role as a Protective Factor in Allergy

Association of vitamin D levels and VDR variant (rs2228570) with allergic rhinitis: A meta-analysis and trial sequential analysis

Background

Allergic rhinitis (AR) is a most common allergic condition characterised by cough, sneezing and flu-like symptoms. The aetiology of AR is not known. A deficiency of vitamin D has been associated with various allergic diseases. The role of vitamin D in allergic rhinitis has been explored in different populations, but the results remained inconsistent. Furthermore, vitamin D exerts its effect through the vitamin D receptor (VDR), and genetic variations in the VDR gene significantly alter vitamin D. We performed a meta-analysis to investigate the role of vitamin D levels and VDR polymorphisms with a predisposition to the development of AR.

Materials and methods

All published articles were searched using databases such as PubMed, Google Scholar, and Science Direct. Based on rigorous inclusion and exclusion, appropriate studies were identified. Vitamin D levels, VDR genotype and allele frequencies were extracted from the eligible reports. The meta-analysis was performed by comprehensive meta-analysis software v3.3.

Results

The present meta-analysis comprised 14 reports with 1504 AR patients and 1435 healthy controls. Compared to healthy controls, AR had significantly lower levels of vitamin D (P = 0.000, standard difference of means = -1.287, 95% CI = -1.921 to -0.652). The meta-analysis of two separate investigations, which included 917 cases and 847 controls, showed no predisposition to allergic rhinitis. The trial sequential analysis also demonstrated the need for future case-control studies of VDR polymorphism to examine their involvement in AR.

Conclusions

Lower vitamin D levels are associated with allergic rhinitis, and vitamin D supplementation might be advantageous in addition to standard treatment. The connection of VDR polymorphism (rs2228570) remained equivocal, and additional research is needed.

Summary

Vitamin D exerct its beneficial effect through the vitamin D receptor (VDR) and role of vitamin D and VDR variant in the allergic rhinitis has been contradictories. We performed a meta-analysis to draw a definitive conclusion of importance of vitamin D and VDR polymorphisms in predisposition to development of allergic rhinitis. The observations of the meta-analysis revealed a significant association of lower vitamin D with allergic rhinitis. In addition the VDR rs2228570 variant predisposed subject to develop rhinitis. Collectively, the results of the present investigation redirect requirement of individualized vitamin D supplementation in the management of allergic rhinitis.

Vitamin D: A Potential Mitigation Tool for the Endemic Stage of the COVID-19 Pandemic?

The impact of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and associated development of clinical symptoms of COVID-19 have presented an enormous global impact on our health care systems, public health and economy. To date several observational epidemiological studies consistently found that vitamin D deficiency, measured as low levels of circulating 25-hydroxyvitamin D, is associated with cardiovascular diseases, diabetes, certain cancers, autoimmune diseases and many infectious diseases, including acute respiratory infections. Since vitamin D is not merely immunosuppressive but also acts as an immunomodulator in tolerance and homeostasis, many experts have considered a role of vitamin D in the prevalence and severity of immune mediated inflammatory diseases, such as SARS-CoV-2, adding to the evidence of the importance of vitamin D in the immune response against viral respiratory infections and reinforcing the need for targeted vitamin D supplementation, with a focus on high-risk populations and a high-dose supplementation treatment for COVID-19 hospitalized patients. The expected transition to endemicity of SARS-CoV-2 even further corroborates as a potential of vitamin D as an potential mitigation tool for the prevention of COVID-19. The aim of this paper is to analyse the current evidence regarding vitamin D and present a hypothesis of its potential role in the current COVID-19 pandemic and in the future as a potential preventive measurement in public health.

Effects of Supplementation in Vitamin D3 Deficient or Insufficient Children with Allergic Diseases

Background and Objectives: Although vitamin D insufficiency or deficiency is prevalent in children with allergic diseases, recommendations for supplementation dosing regimens are imprecise and variable in the literature, because clinical trials aiming to determine optimal doses were scarce in the past. This study aimed to investigate supplementation of vitamin D3 that may achieve therapeutically effective but not toxic serum levels in a subpopulation of children with allergic diseases and concomitant hypovitaminosis D. Materials and Methods: The retrospective, observational study with a cross-sectional design included 94 children suffering from allergic diseases and having vitamin D deficiency/insufficiency who were prescribed high-dose vitamin D3 supplementation by a pediatrician for at least 6 weeks and not more than 9 weeks. Serum levels of the major metabolite of vitamin D (25-(OH)D) were determined in all children twice: before and two weeks after the end of vitamin D3 supplementation. Results: An increase in serum level of the 25-(OH)D after supplementation was significant. However, if the subjects had higher serum levels of the 25-(OH)D before the supplementation, and if the supplementation lasted 8 instead of 6 weeks, the absolute increase in serum level of the 25-(OH)D was lower. Patients taking corticosteroids as inhalation or intranasally had a more intense effect of vitamin D3 supplementation, i.e., the absolute increase in levels of 25-(OH)D was higher than in patients not using such medication. Conclusions: Vitamin D deficiency and insufficiency in children with allergic diseases can be treated with maximal recommended doses of vitamin D3 for a short period of time, especially if they were prescribed with inhalation or intranasal corticosteroids.

Immunity boosting nutraceuticals: Current trends and challenges

The immune function of the human body is highly influenced by the dietary intake of certain nutrients and bioactive compounds present in foods. The preventive effects of these bioactive ingredients against various diseases have been well investigated. Functional foods are consumed across various diverse cultures, in some form or the other, which provide benefits greater than the basic nutritional needs. Novel functional foods are being developed using novel bioactive ingredients such as probiotics, polyunsaturated fatty acids, and various phytoconstituents, which have a range of immunomodulatory properties. Apart from immunomodulation, these ingredients also affect immunity by their antioxidant, antibacterial, and antiviral properties. The global pandemic of Severe Acute Respiratory Syndrome Coronavirus-2 has forced the scientific community to race against time to find a proper and effective drug or a vaccine. In this review, various non-pharmacological interventions using nutraceuticals and functional foods have been discussed. PRACTICAL APPLICATIONS: Despite a plethora of research being undertaken to understand the immunity boosting properties of the various bioactive present in food, the findings are not translating to nutraceutical products in the market. Immunity has proved to be one of the most important factors for the health and well-being of an individual, especially when the world has been under the grip of the novel coronavirus Severe Acute Respiratory Syndrome Coronavirus-2. The anti-inflammatory properties of various nutraceuticals can come out as potential inhibitors of the various inflammatory processes such as cytokine storms, usually being observed in COVID 19. This review gives an insight into how various nutraceuticals can help in the prevention of various diseases through different mechanisms. The lack of awareness and proper clinical trials pose a challenge to the nutraceutical industry. This review will help and encourage researchers to further design and develop various functional foods, which might help in building immunity.

Effects of Serum Vitamin D Levels and Vitamin D Supplementation on Urticaria: A Systematic Review and Meta-Analysis

(1) Backgrounds: Several studies have shown that the level of 25-hydroxyvitamin D (25(OH)D) could affect urticaria. The association of Vitamin D (VitD) with urticaria has not been well established. (2) Methods: The up-to-date meta-analysis was performed to synthesize the new findings. We performed a systematic search in PubMed, EMBASE, Web of Science, and Cochrane Database. We included the observational studies with the comparisons of 25(OH)D between urticarial populations and controls and clinical studies with the clinical severity of urticaria records. (3) Results: A meta-analysis of seventeen studies of urticaria group vs. controls revealed a mean difference of −9.35 ng/mL (95% CI −12.27 to −6.44). There was also an association of urticaria with VitD deficiency. In the subgroup analysis of age and disease type, significant effects of 25(OH)D were found among adult and chronic urticarial populations. Six VitD supplementation trials showed a significant reduction in clinical urticarial score on intervention with VitD with the standard mean difference of −3.63 and −1.54 among randomized control studies and repeated measure trials, respectively. (4) Conclusions: The urticarial population, especially the adult chronic urticarial patients, may be associated with a high risk for lower serum 25(OH)D. VitD supplementations could result in a reduction of urticarial clinical symptoms.

Vitamin D and Allergy Susceptibility during Gestation and Early Life

Worldwide, the prevalence of allergies in young children, but also vitamin D deficiency during pregnancy and in newborns is rising. Vitamin D modulates the development and activity of the immune system and a low vitamin D status during pregnancy and in early life might be associated with an increased risk to develop an allergy during early childhood. This review studies the effects of vitamin D during gestation and early life, on allergy susceptibility in infants. The bioactive form of vitamin D, 1,25(OH)2D, inhibits maturation and results in immature dendritic cells that cause a decreased differentiation of naive T cells into effector T cells. Nevertheless, the development of regulatory T cells and the production of interleukin-10 was increased. Consequently, a more tolerogenic immune response developed against antigens. Secondly, binding of 1,25(OH)2D to epithelial cells induces the expression of tight junction proteins resulting in enhanced epithelial barrier function. Thirdly, 1,25(OH)2D increased the expression of anti-microbial peptides by epithelial cells that also promoted the defense mechanism against pathogens, by preventing an invasive penetration of pathogens. Immune intervention by vitamin D supplementation can mitigate the disease burden from asthma and allergy. In conclusion, our review indicates that a sufficient vitamin D status during gestation and early life can lower the susceptibility to develop an allergy in infants although there remains a need for more causal evidence.

Association of Serum Vitamin D and Immunoglobulin E Levels With Severity of Allergic Rhinitis

Objective The aim of this study was to determine the association of serum vitamin D and immunoglobulin E (IgE) levels with the severity of allergic rhinitis (AR). Methods This case-control study was conducted at Mayo Hospital, Lahore, from June to September 2020 after obtaining ethical approval. Patients of AR were included and divided with the help of allergic rhinitis and its impact on asthma (ARIA) classification, into group A (cases), patients presenting with moderate to severe symptoms, and into group B (control), patients with mild symptoms, after treatment of AR. The mean difference between serum IgE and serum Vitamin D levels of both groups were compared by t-test. Association was determined by logistic regression and odds ratio. Results A total of 224 patients were included in the study, 112 patients in group A and 112 patients in group B. There were 106 (47.3%) female and 118 (52.7%) male. The mean age of patients in group A was 26.78± 8.92 years and in group B, it was 25.72±8.12 years. Mean serum vitamin D levels in group A were 16.24±6.7 ng/ml and in group B 26.92±35 ng/ml (p=0.0001). Mean serum IgE levels in group A were 383.69±154.86 IU/ml and in group B, they were 373.03±106.83 IU/ml (p=0.0001). Vitamin D deficient patients were 24 times more likely to develop moderate to severe AR disease. Conclusion This study showed that in moderate-severe AR, IgE levels are raised statistically as compared to mild AR and the deficiency of Vitamin D is associated with increasing severity of allergic rhinitis symptoms.

The Effect of Vitamin D Supplementation on Clinical Outcomes of Asthmatic Children with Vitamin D Insufficiency

BACKGROUND

The extensive impacts of vitamin D on the immune system has gathered the attention of scholars in last years. In this regard, studies about vitamin D and incidence of asthma have showed various results. The aim of this study was to evaluate the effect of vitamin D supplements on clinical outcomes in asthmatic children with vitamin D insufficiency.

MATERIALS & METHODS

This before-after interventional study was conducted on all asthmatic children who attended the Be'sat Hospital, Iran. Serum levels of 25(OH)D, asthma severity and pulmonary function tests before and after therapeutic prescription of vitamin D were evaluated. Serum levels of 25(OH)D were measured by enzyme-linked immunosorbent assay.

RESULTS

The mean age of the samples was 10.69±9.78 years and 39 subjects (57.4%) were male. The primary mean level of serum 25(OH)D (18.21±8.22, ng/mL) has significantly (p<0.05) increased after treatment (35.45±9.35, ng/mL). Also, asthma severity, forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and FEV1/FVC indicators were significantly (p<0.05) increased after treatment.

CONCLUSION

We can conclude that therapeutic prescription of vitamin D is very effective in improving the clinical status of asthmatic children.

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

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

Contribution of early nutrition on the development of malnutrition and allergic diseases in the first year of life: a study protocol for the Mother and Infant Cohort Study (MICOS)

BACKGROUND

Nutrition and environmental factors are essential for the education of the neonatal immune system. Epidemiological evidence has shown that malnutrition and allergic diseases that occur during early childhood share similar protective and risk factors. This paper describes the protocol of the Mother and Infant Cohort Study (MICOS), which aims to determine the contribution of early nutrition to the development of malnutrition and allergic diseases in infants' first year of life.

METHODS

MICOS is a prospective cohort study conducted at selected government health clinics in two states, namely Selangor and Wilayah Persekutuan Kuala Lumpur, Malaysia. Women in their third trimester of pregnancy are recruited into the study and their infants will be followed-up at 3, 6, and 12 months of age. Information on prenatal factors including socio-demographic characteristics, obstetric history, pre-pregnancy body mass index, gestational weight gain, smoking, family history of allergic diseases, maternal dietary intake and sunlight exposure during pregnancy are obtained through face-to-face interviews. Postnatal factors including dietary intake, sun exposure, and anthropometric measurements of the mothers, as well as feeding practices, dietary intake, anthropometric measurements, and development of allergic diseases of the infants are assessed at each follow-up. Blood samples are collected from the mothers in the third trimester to determine 25-hydroxyvitamin D levels as well as from the infants at age 12 months to determine atopic sensitisation.

DISCUSSION

The concept of developmental origins of health and disease (DOHaD) which emphasises on the role of early life environments in shaping future health and disease susceptibility in adulthood has gained a huge interest in recent years. The DOHaD paradigm has influenced many fields of research including malnutrition and allergic diseases. While findings from the developed countries remain controversial, such studies are scarce in developing countries including Malaysia. The present study will determine the cause and effect relationship between early nutrition and the development of malnutrition and allergic diseases in infants' first year of life.

Early Infant Feeding Practices as Possible Risk Factors for Immunoglobulin E-Mediated Food Allergies in Kuwait

Objective

Early feeding and infant exposures have been suggested as potential risk factors for immunoglobulin E- (IgE-) mediated food allergy (FA). We aimed to evaluate the association between IgE-mediated FA in children and early exposures including the child's nutritional status, breastfeeding and its duration, the age at which the solid food was first introduced, antibiotic exposure during the first year of life, and the child's vitamin D status during infancy.

Design

A case-control study.

Setting and Subjects

Children aged 0–13 years were recruited from pediatric allergy and immunology clinics (PAICs) located at major government hospitals in Kuwait (total FA cases: n = 100; boys = 67%), and healthy controls (n = 100, boys 55%) were recruited from various vaccination units at primary healthcare centers.

Results

Cow's milk allergy was the most common type of FA. FA status was independently associated with the early exposures of exclusive breastfeeding (aOR = 15.55 (3.26–74.19), p = 0.001), vitamin D deficiency or insufficiency during infancy (aOR = 5.42 (1.92–15.30), p = 0.001), and antibiotic exposure during the first year of life (aOR = 5.00 (1.58–15.84), p = 0.006).

Conclusions

FA is highly prevalent among children in Kuwait, and our data indicate that early nutrition-related and antibiotic exposures are associated with FA risk.

Correlation between the vitamin D levels and asthma attacks in children: Evaluation of the effects of combination therapy of atomization inhalation of budesonide, albuterol and vitamin D supplementation on asthmatic patients

The aim of the present study was to analyze the correlation between the vitamin D (VitD) levels and asthma attack in children, and to evaluate the effects of combination therapy of atomization inhalation of budesonide, albuterol and VitD supplementation on asthmatic children. The total sample size comprised of 96 children with asthma from the time period between May 2015 to April 2016. At the same time, 96 healthy children were also selected from the physical examination center for comparison study. The levels of serum VitD in both groups were detected by the enzyme-linked immunosorbent assay (ELISA). Pulmonary function index that includes the measurement of FEV1, FVC, FEV1/FVC, MEF25 and MEF50 were performed to analyze the results. The patients in the control group were treated with only the budesonide therapy and the patients in the observation group were treated with atomization inhalation of budesonide combined with salbutamol and VitD supplementation. After the treatment, the levels of inflammatory cell indicators (IL-2, IL-4, IL-6 and IFN-γ) and pulmonary function in the two groups were compared. The levels of serum VitD in the children with asthma were significantly lower than those in the normal children. The serum IgE level in children with asthma was significantly higher than that in the normal children (P<0.05). Pearson correlation coefficient analyses showed that VitD levels were not correlated with FEV1, FVC and FEV1/FVC levels (P>0.05), but was positively correlated with MEF25 and MEF50 (P<0.05). After the treatment, the levels of IL-2 and IFN-γ in the observation group were significantly higher and levels of IL-4 and IL-6 were significantly lower than those in the control group (P<0.05). The pulmonary function (FEV1, FVC, FEV1/FVC, MEF25 and MEF50) of the observation group was better than that of the control group (P<0.05). The serum VitD levels of children with asthma were closely related to the acute asthmatic attacks. The lower the levels of serum VitD further leads to higher possibility of asthmatic attacks. Atomization inhalation of budesonide combined with albuterol and VitD supplementation can significantly improve the inflammatory response of the children with asthma.

Immune Modulation by Vitamin D and Its Relevance to Food Allergy

Apart from its classical function in bone and calcium metabolism, vitamin D is also involved in immune regulation and has been linked to various cancers, immune disorders and allergic diseases. Within the innate and adaptive immune systems, the vitamin D receptor and enzymes in monocytes, dendritic cells, epithelial cells, T lymphocytes and B lymphocytes mediate the immune modulatory actions of vitamin D. Vitamin D insufficiency/deficiency early in life has been identified as one of the risk factors for food allergy. Several studies have observed an association between increasing latitude and food allergy prevalence, plausibly linked to lower ultraviolet radiation (UVR) exposure and vitamin D synthesis in the skin. Along with mounting epidemiological evidence of a link between vitamin D status and food allergy, mice and human studies have shed light on the modulatory properties of vitamin D on the innate and adaptive immune systems. This review will summarize the literature on the metabolism and immune modulatory properties of vitamin D, with particular reference to food allergy.