The Role of Vitamin D in Allergic Diseases in Children

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

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

Vitamin D status can affect COVID-19 outcomes also in pediatric population

Background

vitamin D influences the immune system and the inflammatory response. It is known that vitamin D supplementation reduces the risk of acute respiratory tract infection. In the last two years, many researchers have investigated vitamin D's role in the pathophysiology of COVID-19 disease.

Results

the findings obtained from clinical trials and systematic reviews highlight that most patients with COVID-19 have decreased vitamin D levels and low levels of vitamin D increase the risk of severe disease. This evidence seems to be also confirmed in the pediatric population.

Conclusions

further studies (systematic review and meta-analysis) conducted on children are needed to confirm that vitamin D affects COVID-19 outcomes and to determine the effectiveness of supplementation and the appropriate dose, duration and mode of administration.

The Crosstalk between Vitamin D and Pediatric Digestive Disorders

Vitamin D is a cyclopentane polyhydrophenanthrene compound involved mainly in bone health and calcium metabolism but also autophagy, modulation of the gut microbiota, cell proliferation, immune functions and intestinal barrier integrity. The sources of vitamin D include sunlight, diet and vitamin D supplements. Vitamin D3, the most effective vitamin D isoform is produced in the human epidermis as a result of sunlight exposure. Vitamin D undergoes two hydroxylation reactions in the liver and kidney to reach its active form, 1,25-dihydroxyvitamin D. Recent studies highlighted a complex spectrum of roles regarding the wellbeing of the gastrointestinal tract. Based on its antimicrobial effect, it was recently indicated that vitamin D supplementation in addition to standard eradication therapy might enhance H. pylori eradication rates. Moreover, it was suggested that low levels of vitamin D might also be involved in the acquisition of H. pylori infection. In terms of celiac disease, the negative effects of vitamin D deficiency might begin even during intrauterine life in the setting of maternal deficiency. Moreover, vitamin D is strongly related to the integrity of the gut barrier, which represents the core of the pathophysiology of celiac disease onset, in addition to being correlated with the histological findings of disease severity. The relationship between vitamin D and cystic fibrosis is supported by the involvement of this micronutrient in preserving lung function by clearing airway inflammation and preventing pathogen airway colonization. Moreover, this micronutrient might exert anticatabolic effects in CF patients. Inflammatory bowel disease patients also experience major benefits if they have a sufficient level of circulating vitamin D, proving its involvement in both induction and remission in these patients. The findings regarding the relationship between vitamin D, food allergies, diarrhea and constipation remain controversial, but vitamin D levels should be monitored in these patients in order to avoid hypo- and hypervitaminosis. Further studies are required to fill the remaining gaps in term of the complex impact of vitamin D on gastrointestinal homeostasis.

Immunomodulatory diet in pediatric age

In the last few decades, the importance of a functioning immune system and health status has become more evident. Multiple factors are able to influence the development of chronic diseases and diet is one of the most important environmental factors. Evidence demonstrates that dietary patterns high in fat and low in fiber are associated with the development of non-communicable diseases. Moreover, optimal nutritional status can modulate immune maturation and response to inflammation. During inflammatory conditions, nutritional deficiencies may occur, establishing a vicious circle, consequently a balanced nutritional status is essential to prevent and counteract infections. Dietary diversity can prevent allergic diseases and nutrients such as DHA, arginine, vitamins and trace elements have an impact on physical barriers (such as gut mucosal barrier and skin), on the immune system response and on microbiome modulation. Protein deficiencies can compromise innate and adaptive immune functions; arginine availability can affect the immune response in injured states and other disease processes; EPA and DHA can modulate both innate and adaptive immunity; prebiotics have a beneficial effect on the functioning of the immune system. Zinc, copper, selenium and iron are involved in the correct development and function of the immune system. Vitamins D, E, A, B and C have a role on immune system through different mechanisms of action. Since a complex interplay exists between diet, microbiome and epigenetic factors which determine nutrient-induced changes on the immune function, the effect of each single nutrient may be difficult to study. Well-designed intervention studies, investigating the effects of whole dietary pattern, should be performed to clarify impact of foods on the immune function and disease risk.

Vitamin D and iron status in children with food allergy

BACKGROUND

Children with food allergy are at specific risk for nutritional deficiencies.

OBJECTIVE

To retrospectively determine prevalence of vitamin D and iron deficiencies in children with or without food allergy (FA).

METHODS

We compared the markers of vitamin D and iron status of 0 to 17-year-olds with cow's milk allergy (CMA) (n = 77), those with other FAs (n = 70), and those with atopy without FA (n = 87) at an academic pediatric allergy practice. Multiple linear regression analyses were performed to determine the impact of CMA and other FAs on vitamin D levels and iron markers.

RESULTS

Vitamin D deficiency was detected in one-fourth and insufficiency in one-third of children with CMA and other FAs and in those with atopic diseases but no FA, respectively. Vitamin D levels were associated with vitamin D supplementation and consumption of breast milk, cow's milk, infant formula, or plant-based milk beverage, but not with CMA or other FAs. Older children with FA who did not consume any cow's milk or alternative milk beverage were at highest risk for vitamin D insufficiency. Children with CMA have a higher rate of iron deficiency anemia (8%) than children with other FAs (1%) or those with no FA (5%, P < .001); however, suboptimal levels of transferrin saturation and iron were detected in up to one-third of children with CMA or other FAs.

CONCLUSION

Vitamin D deficiency and insufficiency is common in children with atopy overall, but children with CMA are at higher risk for iron deficiency anemia. Intensive nutritional counseling and nutrient intake monitoring, specifically for vitamin D and iron in those avoiding cow's milk, are necessary to optimize nutritional status.

Correlation of serum vitamin D levels with severity of pediatric atopic dermatitis and the impact of vitamin D supplementation on treatment outcomes

INTRODUCTION

There is scarcity of prospective studies assessing the correlation between vitamin D deficiency and atopic dermatitis (AD).

MATERIALS AND METHODS

We conducted a prospective study where in serum 25-hydroxy-vitamin D levels were measured in 35 AD patients and 35 age and sex-matched controls. AD patients deficient in vitamin D were supplemented with 1000 IU of vitamin D per day for three months. Serum vitamin D levels and SCORAD were again measured at the end of three months in all AD patients.

RESULTS

The baseline vitamin D levels in patients and controls did not have any statistically significant difference (p = .97). There was a statistically significant (p = .02) inverse relationship between the AD severity and serum vitamin D levels at baseline (r = -0.52). Maximum reduction in SCORAD (41.4 ± 12.7) after 3 months of vitamin D supplementation was seen in severe AD and the minimum (2.4 ± 13.2) in mild AD (p = .0003).

CONCLUSIONS

We found no difference in the mean serum vitamin D levels between AD patients and controls. An inverse correlation was seen between serum vitamin D levels at baseline and severity of AD. Beneficial effect of vitamin D supplementation was observed maximally in severe AD as observed by a reduction in SCORAD.

Vitamin D: Immunomodulatory Aspects

Vitamin D is a group of liposoluble prohormones consisting of 5 different vitamins, the most important forms being vitamin D2 and vitamin D3. The ergocalciferol (vitamin D2) is less efficacious and derives from irradiated fungi, while colecalciferol (vitamin D3), derived from cholesterol, is synthesized via ultraviolet B rays in animal organisms. Only the ultraviolet B rays (290 to 315 nm) portion of the solar ray photolyzes 7-dehydrocholesterol in the skin to previtamin D3, which is converted subsequently to vitamin D3. Moreover, the skin makes little vitamin D from the sun at latitudes above 37 degrees north or below 37 degrees south of the equator. Calcidiol [25(OH)D] is the more stable metabolite of vitamin D in serum and the best indicator of the vitamin D status. Optimal values range are >30 ng/mL. Calcitriol [1,25(OH)2D] is the active hormone form of vitamin D. The 1,25(OH)2D binds to its nuclear receptor (vitamin D receptor), expressed in many tissues, regulating the expression of genes involved in calcium metabolism, cell differentiation, apoptosis, and immunity. About immunity, calcitriol stimulates innate immune responses by enhancing the chemotactic and phagocytotic responses of macrophages as well as the production of antimicrobial peptides. 1,25(OH)2D strongly enhances production of interleukine-10 by stimulating T regulatory cells and inhibiting Th1 and Th17 cell differentiation. Furthermore, several studies suggest that lower 25(OH)D serum levels are associated with an increased risk of respiratory infection at all ages in a dose-response manner.

Prevention and Management of Cow's Milk Allergy in Non-Exclusively Breastfed Infants

Introduction: The prevention and management of cow milk allergy (CMA) is still debated. Since CMA is much less frequent in breastfed infants, breastfeeding should be stimulated. Method: Literature was searched using databases to find original papers and reviews on this topic. Results: Hydrolysates with a clinical proof of efficacy are recommended in the prevention and treatment of CMA. However, not all meta-analyses conclude that hydrolysates do prevent CMA or other atopic manifestations such as atopic dermatitis. There are pros and cons to consider partially hydrolysed protein as an option for starter infant formula for each non-exclusively breastfed infant. A challenge test is still recommended as the most specific and sensitive diagnostic test, although a positive challenge test does not proof that the immune system is involved. The Cow Milk Symptom Score (CoMiSS™) is an awareness tool that enables healthcare professionals to better recognize symptoms related to the ingestion of cow milk, but it still needs validation as diagnostic tool. The current recommended elimination diet is a cow milk based extensive hydrolysate, although rice hydrolysates or soy infant formula can be considered in some cases. About 10 to 15% of infants allergic to cow milk will also react to soy. Mainly because of the higher cost, amino acid based formula is reserved for severe cases. There is no place for infant formula with intact protein from other animals as cross-over allergenicity is high. During recent years, attention focused also on the bifidogenic effect of prebiotics and more recently also on human milk oligosaccharides. A bifidogenic gastrointestinal microbiome may decrease the risk to develop allergic disease. The addition of probiotics and prebiotics to the elimination diet in treatment may enhance the development of tolerance development. Conclusion: Breastfeeding is the best way to feed infants. Cow milk based extensive hydrolysates remain the first option for the treatment of CMA for the majority of patients, while amino acid formulas are reserved for the most severe cases. Rice hydrolysates and soy infant formula are second choice options. Partial hydrolysates with clinical proof of efficacy are recommended in some guidelines in the prevention of CMA and allergic disease in at risk infants, and may be considered as an option as protein source in starter infant formula.