The Association between Vitamin D and Zinc Status with the Disease Onset and Progression of Clinical Symptoms among Outpatients Infected with COVID-19 and Non-Infected Participants: A Cross-Sectional Study

Background: Vitamin D and zinc are important components of nutritional immunity. This study compared the serum concentrations of vitamin D and zinc in COVID-19 outpatients with those of non-infected participants. Clinical symptoms and associations with vitamin D and zinc status were also examined. Methods: A checklist and laboratory examination were applied to collect data in a health service center-based descriptive-analytical cross-sectional study conducted on 53 infected outpatients with COVID-19 and 53 non-infected participants of both sexes. Results: Lower serum concentration of total 25-hydroxyvitamin D [25(OH)D] were observed in patients with moderate illness (18.9±11.5 ng/mL) than in patients with asymptomatic or mild illness (29.2±18.3 ng/mL) (p=0.054). Also, infected patients (100.6±17.8 µg/dL) showed lower serum concentration of zinc than non-infected participants (113.8±13.4 µg/dL) (p=0.013). Patients with normal and insufficient vitamin D status at the time of admission had decreased odds ratios of general symptoms of COVID-19 (odds ratio, 0.19; p≤0.001 for normal and odds ratio, 0.3; p=0.007 for insufficient vitamin D status) compared to patients with vitamin D deficiency. Conclusion: This study revealed the importance of 25(OH)D measurement as a relatively easy option to predict the progression of general and pulmonary symptoms. Also, this study showed that a poor zinc status of the outpatients might affect the disease onset of COVID-19.