Selenium as an Antioxidant: Roles and Clinical Applications in Critically Ill and Trauma Patients: A Narrative Review.

Selenium plays an indispensable role in antioxidant defense through its incorporation into selenoproteins, including glutathione peroxidase (GPx) and thioredoxin reductase. In the context of trauma and critical illness, systemic inflammation and oxidative stress frequently deplete selenium reserves, compromising the body's antioxidant defenses. This deficiency exacerbates immune dysfunction, elevates the risk of multi-organ dysfunction syndrome, and increases susceptibility to infections and mortality. Observational studies have consistently shown that lower selenium levels correlate with poorer clinical outcomes, such as extended stays in intensive care units and higher mortality rates. Supplementation of selenium has demonstrated promise in restoring GPx activity, reducing oxidative stress markers, and supporting recovery, particularly in patients with pre-existing selenium deficiency. While the impact on mortality remains variable across clinical trials, early and targeted supplementation appears to be beneficial, especially when combined with other micronutrients like vitamins C and E or zinc. These combinations enhance the antioxidant response and tackle the complex oxidative pathways in critically ill and trauma patients. Importantly, the clinical benefits of selenium supplementation appear to be influenced by baseline selenium status, with patients exhibiting severe deficiency deriving the most pronounced improvements in oxidative stress markers, immune function, and recovery. This review highlights the critical importance of addressing selenium deficiency, advocating for personalized therapeutic strategies. However, further large-scale studies are essential to optimize dosing regimens, refine combination therapies, and validate selenium's therapeutic potential in trauma and critical care settings.