Pharmacokinetics of Vitamin C: Insights into the Oral and Intravenous Administration of Ascorbate
Puero Rico Health Sciences Journal, 2008, 27(1):7-19
This article is available at: http://prhsj.rcm.upr.edu/index.php/prhsj/article/viewFile/13/11
Duconge J, Miranda-Massari J, González M, Jackson J, Warnock W, Riordan N
There is a strong advocacy movement for large doses of vitamin C. Some authors argue that the biological halflife for vitamin C at high plasma levels is about 30 minutes, but these reports are the subject of some controversy. NIH researchers established the current RDA based upon tests conducted 12 hours (24 half lives) after consumption. The dynamic flow model refutes
the current low-dose recommendations for dietary
intakes and links Pauling’s mega-dose suggestions with
other reported effects of massive doses of ascorbate for
the treatment of disease. Although, a couple of
controlled clinical studies conducted at The Mayo Clinic
did not support a significant benefit for terminal cancer
patients after 10 grams of once-a-day oral vitamin C,
other clinical trials have demonstrated that ascorbate
may indeed be effective against tumors when
administered intravenously. Recent studies confirmed
that plasma vitamin C concentrations vary substantially
with the route of administration. Only by intravenous
administration, the necessary ascorbate levels to kill
cancer cells are reached in both plasma and urine.
Because the efficacy of vitamin C treatment cannot be
judged from clinical trials that use only oral dosing,
the role of vitamin C in cancer treatment should be
reevaluated. One limitation of current studies is that
pharmacokinetic data at high intravenous doses of
vitamin C are sparse, particularly in cancer patients.
This fact needs prompt attention to understand the
significance of intravenous vitamin C administration.
This review describes the current state-of-the-art in oral
and intravenous vitamin C pharmacokinetics. In
addition, the governmental recommendations of dose
and frequency of vitamin C intake will also be
addressed.
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