Vitamin D status and asthma flare-ups in children: a non-systematic review

Abstract

Asthma has assumed global prominence as the most common non-communicable respiratory disease in children. [1] Asthma is now regarded as a heterogeneous disease with several phenotypes and underlying endotypes. [2] Disease heterogeneity is seen in the variable clinical presentations and the nature/extent of airway inflammation and remodeling. Asthma phenotypes and endotypes appear to represent a multitude of the host (gene)-environment reciprocal influences that occur over different periods. [3] Epidemiologic data now indicate that dietary factors, such as hypovitaminosis D, are associated with florid asthma symptoms, asthma flare-ups, decreased lung function and increased drug usage, as well as severe disease. [4] The non-calcemic actions of vitamin D are welldocumented in the medical literature. [5][6][7] Precisely, role of vitamin D in childhood asthma is currently an area of on-going research. The research questions to be addressed should include as follows: First, whether vitamin D supplementation in infancy is protective against viral infections (which could act as triggers to asthma flare-ups). [8] Second, whether vitamin D supplementation could be administered together with inhalational steroid therapy to ameliorate disease flare-ups in school-age children. [8] And third, whether vitamin D supplementation is more effective in populations at risk for hypovitaminosis D. [8] Several studies have highlighted Several non-calcemic actions of vitamin D are well-documented in the literature. Its role in childhood asthma is now an area of on-going research. Studies indicate that the severity of childhood asthma is directly correlated with reduced serum vitamin D levels. This non-systematic review aims to discuss the association of vitamin D status with asthma flare-ups in children. We searched the PubMed database for articles that met the objective of this review. Vitamin D may play a vital role in lung health by inhibiting inflammation, partly by maintaining the regulatory T cells, and by direct induction of innate antimicrobial mechanisms. Vitamin D also inhibits adaptive immunity by delaying the proliferation of T-helper cells. For instance, the neutrophilic asthma phenotype is characterized by neutrophilic inflammation, whose induction is mediated by type 2 T-helper cells. Thus, vitamin D is related to the pathogenesis of asthma based on its ability to block the proliferation of T-helper cells. Predictably, hypovitaminosis D is associated with florid asthma symptoms, asthma flare-ups, decreased lung function, and increased drug usage, as well as severe disease. Several reports have shown a strong relationship between wheezing symptoms/asthma severity in children and low serum 25-hydroxyvitamin D levels. These findings support the use of vitamin D 3 supplementation as a potential strategy for reducing disease flare-ups in children. ABSTRACTSamuel Nkachukwu Uwaezuoke, Adaeze C Ayuk