Micronutrients in Pediatric Asthma: Biological Mechanisms and Clinical Evidence—A Narrative Review

Introduction: Asthma is the most common chronic inflammatory disease in childhood, with complex pathogenesis and heterogeneous clinical manifestations. Current efforts are focused on achieving remission through phenotyping and personalized therapy. Micronutrient deficiency is commonly observed in both children and adults, and current evidence points to their role in the pathogenesis of numerous acute and chronic conditions. Method: In this narrative review, we analyzed current information regarding the influence of micronutrient deficiencies on asthma control. The aim was to clarify the extent to which current knowledge provides evidence for implementing specific dietary measures in children with asthma to achieve disease control. We conducted a review of the literature covering the past 20 years to assess the impact of iron, vitamin D, and folic acid deficiency on asthma control. The research was performed in PubMed, Web of Science, Cochrane Library and Embase. Results: Vitamin D deficiency is associated with the frequency of asthma exacerbations in children. However, data regarding the severity of exacerbations, hospitalizations, or emergency department visits are not consistent across different studies. Vitamin D supplementation has controversial effects on disease control. Iron deficiency may contribute to the development of asthma, but there is no clear evidence. Observational studies have reported associations between iron deficiency, poorer asthma control, frequent exacerbations, and impaired lung function. An association between low folate levels and increased asthma risk and poorer asthma control was also reported. Conclusions: Assessing micronutrient status in children with asthma and the effect of correcting deficiencies as part of a personalized treatment plan to achieve symptom control remains a topic that requires further research.