Association of Vitamin A and E Nutritional Status with Recurrent Respiratory Tract Infections in Children Aged 0–14 Years in Liangshan Region and Construction of a Precision Prevention and Control System

Abstract

Objective: Through a prospective observational study, this research systematically analyzes the nutritional distribution characteristics of serum vitamins A (VA) and E (VE) in children aged 0–14 in the Yi ethnic minority settlement areas of Liangshan, clarifies the pathways through which these two fat-soluble nutrients affect recurrent upper respiratory tract infections via the respiratory mucosal barrier, immune regulation, and antioxidant pathways, and quantifies the dose-effect relationship between serum nutrient levels and infection frequency. It compares the detection rates of nutritional abnormalities and disease characteristics among children of different genders to determine the influence of gender factors. Based on large-sample real-world data, it constructs an integrated prevention and control system of “precise detection–risk stratification– individualized intervention”, providing localized evidence-based foundations and practical solutions for comprehensive prevention and control of respiratory tract infections in children in Liangshan and surrounding areas. Methods: The study was conducted at Huili and Huidong Maternal and Child Health Hospitals, involving 1,148 children aged 0–14 who visited the pediatric and child health departments of the two hospitals from June 2023 to November 2025. Face-to-face surveys were conducted using a uniformly designed questionnaire to collect children’s demographic characteristics, frequency of upper respiratory tract infections in the past year, daily dietary structure, and nutrient supplementation behaviors. Venous or capillary blood samples were collected following standardized procedures, and serum VA and VE concentrations were measured using liquid chromatography-tandem mass spectrometry. Subgroups were divided based on annual infection frequency to analyze the changing patterns of serum VA and VE concentrations and the detection rates of nutritional abnormalities across different frequencies. Observational indicators were compared between genders. Pearson linear correlation analysis was used to assess the strength of the association between nutrient levels and infection frequency. This study is observational and did not implement uniform interventions for children with nutritional abnormalities, nor did it evaluate intervention effects. Prevention and control strategies were derived solely from baseline observational data. Results: Among the 1,148 children, 835 had one episode of upper respiratory tract infection in the past year, 139 had two episodes, 90 had three episodes, 41 had four episodes, 24 had five episodes, 10 had six episodes, and 9 had seven or more episodes. As the frequency of infection episodes increased, the average serum concentrations of VA and VE in children showed a continuous gradient decline, while the detection rates of marginal VA deficiency, clinical VA deficiency, and potential VE deficiency increased simultaneously. Gender-stratified analysis revealed no statistically significant differences (p > 0.05) in serum VA/VE levels, detection rates of various nutritional abnormalities, or annual infection frequencies between male and female children. Pearson correlation analysis showed a significant negative correlation between serum VA and VE levels and the annual frequency of upper respiratory tract infections (r = -0.711, r = -0.620, p < 0.001). VA primarily reduces infection risk by maintaining the integrity of the respiratory epithelium and regulating immune cell function; VE alleviates airway inflammatory responses through antioxidant effects, with both exhibiting synergistic protective effects. Higher infection frequencies were associated with elevated levels of inflammatory markers such as peripheral blood leukocytes, neutrophils, and C-reactive protein, and lower hemoglobin levels (p < 0.001). Children who regularly took vitamin AD preparations had higher baseline serum VA levels and lower annual frequencies of upper respiratory tract infections. Conclusion: There is a clear negative gradient correlation between serum VA and VE levels and the frequency of upper respiratory tract infections in children aged 0–14 in Liangshan. Vitamins A and E influence the occurrence and persistence of respiratory tract infections from multiple dimensions, including mucosal defense, immune regulation, and antioxidation. Nutritional deficiencies significantly increase children’s susceptibility to infections; recurrent infections, in turn, accelerate nutrient consumption, forming a vicious cycle. There are no significant differences in nutritional status and respiratory infection characteristics between male and female children, so gender-specific considerations are unnecessary for nutritional screening and infection prevention in the region. Regular precise serological testing and early identification of nutritional abnormalities are core prerequisites for proactive prevention. On this basis, implementing individualized precise interventions can effectively break the vicious cycle of “nutritional deficiency–recurrent infections”. The integrated precise prevention and control system constructed in this study is well-suited to the primary healthcare conditions in ethnic minority areas of Liangshan, demonstrating strong practicality and potential for widespread application.