The Starfish Project

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Vitamin C: Comparing Oral vs. Intravenous Use

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Background: Vitamin C at high concentrations is toxic to cancer cells in vitro. Early clinical studies of Vitamin C in patients with terminal cancer suggested clinical benefits, but two double-blind, placebo-controlled trials showed none. However, these studies used different routes of administration. One used the intravenous method, while the other used the oral method of administration.

Objective: To determine whether plasma Vitamin C concentrations vary substantially with the role of administration (the way it is delivered to the body).

Setting: Academic medical center

Participants: 17 healthy hospitalized volunteers

Measurements: Vitamin C plasma and urine concentrations were measured after administration of oral and intravenous doses at a dose range of 0.015 to 1.25 grams, and plasma concentrations were calculated for a dose range of 1 to 100 grams.

Results: Peak plasma Vitamin C concentrations were higher after the administration of intravenous doses than after administration of oral doses – and the difference increased according to the dose.

Vitamin C at a dose of 1.25 grams administered orally produced mean peak plasma concentrations of 134.8 – compared with 885 for intravenous administration.

For the maximum tolerated oral dose of 3 grams every four hours, peak plasma concentrations were measured at 220 – compared with a measurement of 13,400 for intravenous administration of 50 grams through intravenous administration. Urine concentrations of Vitamin C from intravenous administration were 140-fold higher than those with maximum oral doses.

Conclusions: Oral Vitamin C produces plasma concentrations that are tightly controlled. Only intravenous administration of Vitamin C produces high plasma and urine concentrations that might have anti-tumor activity. Because 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 re-evaluated.



Written by Tracey

September 25, 2008 at 6:33 pm

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