Association Between Vitamin D Status and Upper Respiratory Tract Infections in Saudi Children Under Five: A Prospective Multi-Center Study

RESUMO

Azizah hendi saleh aljohany*, Fajr Essam Saifuddin, Fatmah Khaled fallatah, Amjad Mustafa Altunusi, Noor Abdulrahman Abdulrahim Basunduwah, Teaf Jamal Mohammed Holbah, Rawiah Yahya Ahmed Mushari, Njood Faris Al-Nahdi, Shatha Abdullah Almuyidi, Abdulaziz Fahad Salamh, Razan Mohammed Alotaibi, Ashwaq Arar Alruwaili, Amal saleh hamdi alsofyany

Background: Vitamin D plays a critical role in immune regulation and has been implicated in susceptibility to respiratory infections, particularly in children. Despite abundant sunlight, vitamin D deficiency remains widespread in Saudi Arabia, especially among infants and toddlers.

Objective: To investigate the association between vitamin D status and the frequency, severity, and recurrence of upper respiratory tract infections (URTIs) in Saudi children under five years of age. Methods: This prospective study enrolled 330 Saudi children aged ≤5 years from multiple healthcare centers. Participants were classified into vitamin D–deficient,–insufficient, or –sufficient groups. Data on URTI episodes, symptom duration, emergency visits, hospitalizations, and seasonal variation were collected and compared. Multivariate logistic regression adjusted for confounders including age, breastfeeding duration, sun exposure, and daycare attendance.

Results: Vitamin D–deficient children experienced significantly more URTI episodes (4.8 ± 1.6) than sufficient children (2.4 ± 1.1, p < 0.001), with longer symptom duration, higher emergency visits (24% vs. 12.4%, p = 0.02), and hospitalizations (8% vs. 2.2%, p = 0.04). Multivariate regression confirmed deficiency as an independent predictor of URTI risk (OR 2.6; 95% CI 1.8–3.7). Risk was also elevated with shorter breastfeeding duration, limited sun exposure, and daycare attendance.

Conclusion: Vitamin D deficiency is strongly associated with increased URTI frequency and severity in young Saudi children. Addressing vitamin D status through supplementation, lifestyle modification, and routine screening may reduce pediatric respiratory infection burden in this population