Severe
respiratory infections are characterized by elevated
inflammation and generation of
reactive oxygen species (ROS) which may lead to a decrease in
antioxidants such as
vitamin C and a higher requirement for the
vitamin. Administration of intravenous
vitamin C to patients with
pneumonia and
sepsis appears to decrease the severity of the disease and potentially improve survival rate. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)
infection causes
pneumonia,
sepsis and
acute respiratory distress syndrome (ARDS) in severe cases, and is referred to as
coronavirus disease 2019 (COVID-19). Patients with
COVID-19 infection also appear to have depleted
vitamin C status and require additional supplementation of
vitamin C during the acute phase of the disease. To date there have been 12
vitamin C and
COVID-19 trials published, including five randomised controlled trials (RCTs) and seven retrospective cohort studies. The current level of evidence from the RCTs suggests that intravenous
vitamin C intervention may improve oxygenation parameters, reduce inflammatory markers, decrease days in hospital and reduce mortality, particularly in the more severely ill patients. High doses of oral
vitamin C supplementation may also improve the rate of recovery in less severe cases. No adverse events have been reported in published
vitamin C clinical trials in
COVID-19 patients. Upcoming findings from larger RCTs will provide additional evidence on
vitamin supplementation in
COVID-19 patients.