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.