Vitamin C / cancer relationship ?

Charles Miller rellim at tulane.edu
Tue Jun 26 14:30:48 EST 2001



The June 15 issue of Science describes work that suggests that vitamin C may
have a dark side---participation in the generation of genotoxic lipid
peroxides (see abstract below). This is not the the first report of a
adverse action of vitamins. Clinical trials with vitamin A (the CARET study)
had to be stopped when the treated group showed an excess incidence of
cancers and cardiovascular disease. Clearly we have much to learn about the
relationships between human nutrition, toxicity, and health.

Chuck 
--

Charles A. Miller, III, Ph.D.
Associate Professor of Environmental Health Sciences
Tulane University School of Public Health and Tropical Medicine
1430 Tulane Ave.
New Orleans, LA 70112
(504)585-6942    rellim at tulane.edu
Bionet.toxicology news group: http://www.bio.net/hypermail/toxicol/current




Vitamin C-Induced Decomposition of Lipid Hydroperoxides to Endogenous
Genotoxins 

Seon Hwa Lee, Tomoyuki Oe, Ian A. Blair*

Epidemiological data suggest that dietary antioxidants play a protective
role against cancer. This has led to the proposal that dietary
supplementation with antioxidants such as vitamin C (vit C) may be useful in
disease prevention. However, vit C has proved to be ineffective in cancer
chemoprevention studies. In addition, concerns have been raised over
potentially deleterious transition metal ion-mediated pro-oxidant effects.
We have now determined that vit C induces lipid hydroperoxide decomposition
to the DNA-reactive bifunctional electrophiles 4-oxo-2-nonenal,
4,5-epoxy-2(E)-decenal, and 4-hydroxy-2-nonenal. The compound
4,5-Epoxy-2(E)-decenal is a precursor of etheno-2'-deoxyadenosine, a highly
mutagenic lesion found in human DNA. Vitamin C-mediated formation of
genotoxins from lipid hydroperoxides in the absence of transition metal ions
could help explain its lack of efficacy as a cancer chemoprevention agent.
Science, Volume 292, Number 5524, Issue of 15 Jun 2001, pp. 2083-2086.
Copyright © 2001 by The American Association for the Advancement of Science. 

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