Therefore, even moderate benefits of an 8–18% decrease in the duration of respiratory virus infections would justify consideration of vitamin C supplementation. However, the new coronavirus causes an illness that is much more severe than ordinary respiratory virus infections and frequently causes pneumonia complicated by ARDS. In the placebo-controlled trials on the common cold ( 12), the magnitude of effect of regularly administered vitamin C has not been very large and does not justify regular vitamin C supplementation in normal situations. Because the effect of vitamin C on the diverse group of respiratory viruses seems non-specific, it seems plausible that vitamin C may also have effects on the new coronavirus. Therefore, types of viruses have varied between the trials and it is unlikely that the benefit of vitamin C is explained by effects on just a certain respiratory virus or virus group. Respiratory viruses form a heterogeneous group and their distribution varies over time and location. A few dozen placebo-controlled trials with humans showed that regularly administered ≥1 g/day vitamin C shortened infections caused by respiratory viruses in adults by 8%, and in children by 18% ( 12). In addition, the deficiency of vitamin C increased lung pathology caused by influenza A in mice ( 11).Ī number of controlled vitamin C trials in humans are also important when considering the new coronavirus. In addition, in septic mice with acute respiratory distress syndrome (ARDS), vitamin C administration downregulated proinflammatory genes, enhanced epithelial barrier function, and improved alveolar fluid clearance ( 9, 10). Vitamin C increased the resistance of chick embryo tracheal organ cultures to infection caused by an avian coronavirus ( 7), and protected broiler chicks against an avian coronavirus ( 8). Several of the numerous animal studies on vitamin C and infections ( 1, 2) are relevant when considering the potential role of the vitamin against the new SARS-CoV-2 coronavirus. Vitamin C is a safe and inexpensive essential nutrient.Įvidence Indicating That Vitamin C Might Influence COVID-19
The effects of vitamin C on acute respiratory distress syndrome (ARDS) frequently complicating COVID-19 pneumonia should be considered. Two randomized placebo-controlled trials found statistically significant reduction in the mortality of sepsis patients. Another meta-analysis found that vitamin C shortened the duration of mechanical ventilation in ICU patients.
A meta-analysis of 12 trials with 1,766 patients calculated that vitamin C reduced the length of ICU stay on average by 8%. Gram doses of vitamin C are needed to increase the plasma vitamin C levels of critically ill patients to the levels of ordinary healthy people. In critically ill patients, plasma vitamin C levels are commonly very low. In a few dozen placebo-controlled trials with humans, vitamin C has shortened infections caused by respiratory viruses, which indicates that the vitamin can also influence viral infections in humans. In numerous animal studies, vitamin C has prevented and alleviated viral and bacterial infections.