Vitamin C exhibits pro-oxidant properties. Nature 1998; 392

[davidshields]

[davidshields]

Interesting reading on this topic:
http://lpi.oregonstate.edu/news/beckman.html

(However, I would still appreciate informed opinions from readers of Vitamin C Foundation forum. Thanks.)

From the link:
It appears, therefore, that the oxidative DNA adducts measured by Podmore et al.1 do not accurately reflect DNA damage in vivo. It is likely that >90% of the DNA adducts were formed ex vivo. The elucidation of ascorbate's in vivo effects on oxidative DNA damage has to rely on more definitive methodologies and more thorough experimentation. In addition, the value of ascorbate as an antioxidant and for human health does not rest on a few measurements of oxidative DNA damage, but rather is supported by hundreds of biochemical, cellular, physiological, nutritional and epidemiological studies18. It would be as unwise to recommend vitamin C supplementation based on a single measurement of decreased oxidative DNA damage as it is to discourage its use based upon this study1.

In conclusion, we believe that the results presented are an ex vivo artifact, given the high values obtained. In the context of the huge literature supporting the health benefits of vitamin C, the conclusions of the study are unwarranted.

[davidshields]

[ofonorow]

Thank you for bringing this up at the forum, as it has probably not been addressed here. The Foundation addressed this pseudo issue years ago, after the first publication in Nature cited above - which has since been retracted by the authros without publicity!

In review, a "bomb" was dropped that generated world-wide publicity. The bomb was based on a letter to Nature (not a peer revied study) regarding in vitro (test tube) experiments with an obscure indicator of oxidation. Later, the authors retracted their findings, with little or no publicity.

The fact is that vitamin C has both pro-oxidant and anti-oxidant effects in the body, as Pauling summarizes in HOW TO LIVE LONGER AND FEEL BETTER (1986, 2006)

The pro oxidant effects are utilized by our immune systems, for example.

But vitamin C is the primary water soluble antioxidant. If you are seriously worried about taking so-called "high" dose of vitamin C, then you have to ask your self why all other animals produce 3000 to 13000 mg (adjusted for body weight) 24/7.

[Bobber]

Cathcart also has This PDF document on his web site which deals with this topic.

[joiv]

"Ascorbate does not act as a pro-oxidant towards lipids and proteins in human plasma exposed to redox-active transition metal ions and hydrogen peroxide."
http://www.ncbi.nlm.nih.gov/entrez/quer ... s=12726918