Relationship Between Serum Metabolites of Carotenoids, Vitamin A, Vitamin E, and Clinical Parameters in COVID-19 Patients

Abstract

Oxidative stress and inflammation play central roles in the immunopathogenesis of COVID-19. In this study, we investigated whether circulating carotenoids, retinol, and vitamin E metabolites can distinguish COVID-19 patients from healthy controls and discriminate disease severity. We analyzed 44 hospitalized COVID-19 patients (23 with moderate disease and 21 with severe disease) and 39 healthy controls recruited from the same hospitals. Plasma concentrations of individual carotenoids, retinol, total vitamin A, vitamin E (gamma-tocopherol, alpha-tocopherol), retinol-binding protein 4 (RBP4), transthyretin (TTR), complete blood count parameters, and clinical chemistry and inflammatory markers were determined and statistically analyzed. Compared with healthy controls, COVID-19 patients had significantly lower concentrations of vitamin E, retinol, total vitamin A, lutein, total carotenoids, and TTR and higher levels of inflammatory markers. In multivariate logistic regression, the RBP4/total vitamin A ratio, gamma-tocopherol, and ferritin emerged as independent factors differentiating COVID-19 patients from healthy controls. Within the patient group, antioxidant micronutrient levels did not differ significantly between moderate and severe COVID-19, whereas inflammatory markers, such as C-reactive protein, ferritin, and the neutrophil-to-lymphocyte ratio, increased with severity. These data indicate that although carotenoids, vitamin A, and vitamin E are markedly depleted during COVID-19, they do not stratify disease severity, whereas the RBP4/total vitamin A ratio, gamma-tocopherol, and ferritin may serve as useful biomarkers for distinguishing COVID-19 from health.