There is a strong advocacy movement for large doses of
vitamin C. Some authors argue that the
biological half-life 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.