Mice and guinea pig vitamin C studies can be flawed

This forum will focus on analyzing recent clinical studies of vitamin C.

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VanCanada

Mice and guinea pig vitamin C studies can be flawed

Post Number:#1  Post by VanCanada » Tue Dec 18, 2012 3:12 pm

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Mice studies can be poor because mice make their own ascorbate.

Studies that use guinea pigs can be poor because guinea pigs can receive some ascorbate from eating the wood chips they are provided as bedding.

Stephen Lawson in 'The Trials and Tribulations of Vitamin C' wrote:Small amounts of supplemental vitamin C (0.076% by weight) administered to mice, a species able to synthesize vitamin C, depress levels of vitamin C in the liver, lung, muscle, spleen, and plasma compared to unsupplemented mice, demonstrating the so-called “mouse effect.” (Ref. 93) To raise the vitamin C level in these tissues (except plasma) in mice, the amount of vitamin C added to the diet must be greater than 0.5% by weight. Additionally, guinea pigs, an excellent animal model for studying vitamin C because of their inability to synthesize the vitamin, maintained on vitamin C deficient diets and housed in cages with wood chips can remain ascorbutic by consuming the chips, which provide enough vitamin C to prevent scurvy. (Ref. 94)

The Real Problem
The magnitude of the precise prophylactic effect of vitamin C against heart disease and cancer remains unresolved, and we have little dose response data on the effect of vitamin C on its manifold biochemical reactions. Studies using the guinea pig model have demonstrated remarkable protective effects of high-dose vitamin C against liver damage and mortality caused by aflatoxin B1 exposure (Ref. 95) and against neuro-lathyrism or death induced by exposure to ß-N-oxalylamino-Lalanine, a potent neurotoxin. (Ref. 96) These results, combined with the aforementioned human studies on lead and vitamin C, show the potential for substantial improvements in public health in regions with high toxicant exposure. We know that vitamin C has an important and underappreciated role in clinical practice and that it is a very safe substance. Studies will continue to report the gamut of beneficial, neutral, or potentially harmful effects of supplemental vitamin C, which must be reviewed carefully and critically. Many, perhaps most, of these studies will be imperfect, containing insignificant flaws or serious problems that render the results questionable. In particular, the news media must endeavor to display much more scientific competence, perspective and technical precision in their coverage of scientific and medical reports on vitamin C. Otherwise, the public may become confused and needlessly suffer. As Wakimoto and Block pointed out, about 50% of older Americans ingest less than the RDA for vitamin C (90 mg/day for men, 75 mg/ day for women), and about 25% ingest less than 50% of the RDA for vitamin C. (Ref. 97) Clearly, inadequate daily intake of vitamin C is among the most serious problems that need to be addressed.

- An excerpt quoted from the PDF file at:

orthomolecular.org/library/jom/2003/pdf/2003-v18n0304-p173.pdf
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