Background: Critical illness is a major promoter of systemic inflammation and organ failure due to oxidative stress, excessive free radical production, and depletion of antioxidant defenses. The aim of this review was to provide a review of recent meta-analyses to determine the effects of vitamin D, antioxidant vitamins (E, C, and β-carotene), selenium, and zinc supplementation in critically ill patients. Methods: Relevant studies were searched in international databases including PubMed/MEDLINE, Science Direct, Scopus, Cochrane Central Library, and Google Scholar up to November 2021. Meta-analysis studies investigating the effects of vitamin D, antioxidant vitamins, and trace elements on outcomes of clinical illness were included in this review. Results: Overall, the results of 31 meta-analyses were reported in the study. The beneficial effects of vitamins D, C, and selenium supplementation in reducing over-all mortality, length of stay in hospital and intensive care unit, secondary infection, duration of mechanical ventilation and other adverse effects related to hospitalization were reported in a number of studies. Adverse and insignificant results were reported regarding vitamin A, vitamin E, β-carotene, and zinc supplementation in critically ill patients. Conclusion: Timing, dosage, and duration of the supplementation still need to be clearly defined. Larger randomized trials are warranted to fully assess the effect of vitamins D, C, and selenium supplementation in the critically ill as adjuvant therapy to routine medications. [ABSTRACT FROM AUTHOR]