Pharmacokinetics of oral vitamin C

Abstract

Purpose. To test whether plasma vitamin C levels, following oral doses in supplemented volunteers, are tightly controlled and subject to a maximum in the region of 220 mM L 21 , as suggested by previous researchers for depleted subjects. To determine plasma levels following single, variable-sized doses of standard and liposomal formulations of vitamin C and compare the effects of the different formulations. To determine whether plasma levels above ,280 mM L 21 , which have selectively killed cancer, bacteria or viruses (in laboratory experiments), can be achieved using oral doses of vitamin C. Design. This was a single blind study, measuring plasma levels in two subjects, in samples taken halfhourly or hourly for 6 hours, following ingestion of vitamin C. Data were compared with published results and with data from 10 years of laboratory plasma determinations. Materials and methods. Standard 1 gram tablets of vitamin C; liposomal vitamin C. Plasma levels were analysed using the method of Butts and Mulvihill. Results. Preliminary investigations of the effects of liposomal and standard formulation ascorbate showed that blood plasma levels in excess of the previously assumed maximum of 220 mM L 21 are possible. Large oral doses of liposomal ascorbate resulted in plasma levels above 400 mM L 21 . Conclusions. Since a single oral dose can produce plasma levels in excess of 400 mM L 21 , pharmacokinetic theory suggests that repeated doses could sustain levels well above the formerly assumed maximum. These results have implications for the use of ascorbate, as a nutrient and as a drug. For example, a short in vitro treatment of human Burkitt's lymphoma cells with ascorbate, at 400 mM L 21 , has been shown to result in ,50% cancer cell death. Using frequent oral doses, an equivalent plasma level could be sustained indefinitely. Thus, oral vitamin C has potential for use as a non-toxic, sustainable, therapeutic agent. Further research into the experimental and therapeutic aspects of high, frequent, oral doses of ascorbic acid either alone or (for cancer therapy) in combination with synergistic substances, such as alpha-lipoic acid, copper or vitamin K3, is needed urgently.

Ameliorative effects of ascorbic acid on rectal temperature, excitability score and liveweight of rabbits transported by road

“…The results further demonstrated that AA began to manifest its action as early as 30 min of its administration, corresponding to the time when the transportation lasted 30 min. This finding agreed with the results of the pharmacokinetic study on vitamin C that AA exerts its effects following 30 min of its oral administration in humans (Hickey et al, 2008). The results of this study further showed that AA exerted a hypothermic effect in treated rabbits, which agree with the previous findings of Ayo et al (2005) in pullets and Minka and Ayo (2007b) the adverse effects of road transportation stress in rabbits, and that the vitamin is beneficial when administered to the animals before the commencement of the journey.…”

Effect of ascorbic acid administration on erythrocyte osmotic fragility of pigs transported by road during the hot-dry season

“…Ascorbic acid is a water-soluble antioxidant vitamin, non-toxic, sustainable and readily metabolized by the body of most domestic animals and humans (Hickey et al 2008;Padayatty et al 2003), when administered orally its absorption takes about 30 min (Hickey et al 2008;Pardue et al 1984;Tsao 1997). Thus, ascorbic acid administration in pigs subjected to road transportation during the harmmatan and goats during the hot-dry season in the Northern Guinea Savannah zone of Nigeria has been shown to decrease RBC osmotic fragility and reduced oxidative damage to RBCs Minka and Ayo 2010).…”

Znaczenie witaminy C dla organizmu człowieka

“…Dodatkowo, jednorazowe dawki powyżej 2 g przy podaniu doustnym mogą działać przeczyszczająco. Zwiększenie wchłaniania przy podaniu doustnym możliwe jest przy zastosowaniu liposomalnej postaci kwasu L(+)-askorbinowego [17]. Uzyskanie znacznie wyższych stężeń o potencjalnym działaniu farmakologicznym w schorzeniach typu reumatoidalnych lub nowotworowych, rzędu milimolowych, jest jednak możliwe tylko w przypadku dożylnego podawania witaminy C [15,18].…”