Clinical Nutrition Open Science · Published 2026-06-19 · DOI 10.1016/j.nutos.2026.100692
Aundrea M. Parker, Sara E. Thomas, Tori A. Holthaus, Bridget A. Cassady
Objectives: To provide a narrative review of randomized controlled trials (RCTs) examining the effects of select high-dose nutrient supplementation on clinical and biological outcomes in patients hospitalized with coronavirus disease 2019 (COVID-19) during the height of the pandemic. Methods: PubMed and Embase were searched for RCTs published from January 2020 to September 2023. Eligible studies examined nutrient dosage and their effects on clinical outcomes and biochemical markers. Results: Thirty-nine RCTs assessed high-dose zinc, vitamins C and D, omega-3 fatty acids, glutamine, or arginine in patients hospitalized with COVID-19. Zinc did not consistently improve length of stay (LOS), mortality, or ventilation, though some trials reported faster olfactory recovery and reduced intensive care unit (ICU) admissions. Vitamin C showed mixed effects on LOS, oxygenation, and mortality, with potential benefits in multi-nutrient regimens. Vitamin D supplementation generally showed no improvement in major clinical outcomes; however, select trials using vitamin D analogs reported improved oxygenation and reduced ICU admissions. Omega-3 fatty acids administered with enteral feedings, glutamine, and arginine demonstrated immunomodulatory effects, including reductions in pro-inflammatory cytokines and C-reactive protein, with occasional improvements in survival or respiratory function. Conclusions: High-dose nutrient interventions in patients hospitalized with COVID-19 were heterogeneous. Variability in nutrient doses and intervention durations limits conclusions regarding the efficacy of supplying nutrients beyond physiological needs in critical care. Future studies incorporating physiologically informed dosing, routine nutrient status assessments, and reporting of concurrent nutritional intake may help clarify the clinical and biological effects of high dose nutrient supplementation during critical illness.
Abstract from DOAJ. Public domain (CC0 1.0).
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Parker, A., Thomas, S., Holthaus, T., et al. (2026). Lessons from COVID-19: High-dose nutrient supplementation and implications for critical care. Clinical Nutrition Open Science. https://doi.org/10.1016/j.nutos.2026.100692