Update on vitamin C administration in critical illness.

Abstract

Several studies have recently explored the effects of intravenous vitamin C in sepsis. We aimed to summarize their findings to provide perspectives for future research. Sepsis trials examined 6 g/day of intravenous vitamin C with or without the thiamine and/or hydrocortisone compared with placebo or hydrocortisone. Network meta-analysis reported that intravenous vitamin C, thiamine, hydrocortisone, or combinations of these drugs was not proven to reduce long-term mortality. However, the component network meta-analysis suggested an association of high-dose (>6 g/day) and very-high dose vitamin C (>12 g/day) and decreased mortality but with low certainty. The preclinical investigations have, however, advanced to much higher doses of intravenous vitamin C therapy since a scoping review on harm reported that mega-doses of intravenous vitamin C (50-100 g/day) had been administered without any conclusive adverse effects. In a Gram-negative sheep model, renal tissue hypoperfusion was reversed, followed by improvements in kidney function when a mega-dose of vitamin C (150 g/day equivalent) was administered. The effect of intravenous vitamin C in critically ill patients has yet to be determined and might be dose-dependent. Clinical studies of very high or mega doses of vitamin C are justified by preclinical data.