Effects of intravenous administration of ascorbic acid (vitamin C) on oxidative status in healthy adult horses.
Authors: Taylor Sandra D, Hart Kelsey A, Vaughn Sarah, Giancola Shyla C, Serpa Priscila B S, Santos Andrea P
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Intravenous Vitamin C in Healthy Horses Oxidative stress drives tissue damage in septic and critically ill horses, prompting investigation into whether high-dose intravenous ascorbic acid might serve as adjunctive therapy; however, the optimal dosing strategy and mechanism of action in equine patients remained poorly characterised. In a randomised, placebo-controlled crossover trial, eight healthy horses received single intravenous doses of ascorbic acid at 25, 50, and 100 mg/kg (plus saline placebo), with blood sampled at baseline, 2 and 6 hours to measure plasma ascorbic acid concentrations, reactive oxygen metabolites (dROM), intracellular red blood cell and neutrophil reactive oxygen species production, and plasma antioxidant capacity using photometry, flow cytometry, and fluorometric assays. Only the highest dose (100 mg/kg) produced a measurable antioxidant effect—a statistically significant reduction in dROM at 2 hours post-administration—whilst lower doses and all treatment groups showed no effect on intracellular ROS generation or overall plasma antioxidant capacity. These findings suggest that clinicians exploring vitamin C supplementation in septic cases may need to consider doses at the higher end of the range, though the modest and transient nature of the observed benefit warrants caution; the lack of effect on cellular ROS production particularly questions whether IV ascorbic acid influences the oxidative mechanisms most relevant to sepsis-induced tissue injury in horses.
Read the full abstract on PubMed
Practical Takeaways
- •High-dose IV vitamin C (100 mg/kg) may reduce circulating oxidative metabolites in horses, but clinical significance is unclear given lack of effect on other oxidative markers
- •Vitamin C appears safe for IV administration in horses with dose-dependent plasma concentration increases, but current evidence does not support routine use for improving antioxidant status in healthy animals
- •If considering vitamin C as adjunctive sepsis therapy, recognize that evidence from this healthy horse model is limited and therapeutic efficacy in septic patients remains unproven
Key Findings
- •Ascorbic acid at 100 mg/kg decreased plasma dROM (determinants of reactive oxygen metabolites) by 63.3 units at 2 hours post-treatment (P = 0.03)
- •Plasma ascorbic acid concentrations increased in a dose-dependent manner across 25, 50, and 100 mg/kg doses
- •No significant effects of any AA dose on basal or stimulant-induced intraerythrocytic ROS, neutrophil ROS production, or plasma antioxidant capacity at any timepoint
- •High-dose IV ascorbic acid (100 mg/kg) showed limited antioxidant benefits in healthy horses, with only dROM reduction demonstrated