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 mML 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 mML 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 mML 21 are possible. Large oral doses of liposomal ascorbate resulted in plasma levels above 400 mML 21 . Conclusions . Since a single oral dose can produce plasma levels in excess of 400 mML 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 mML 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.