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High
doses of multiple antioxidant vitamins: essential ingredients in improving the
efficacy of standard cancer therapy
Prasad
KN, Kumar A, Kochupillai V, Cole WC
Center
for Vitamins and Cancer Research, Department of Radiology, School of Medicine,
University of Colorado Health Sciences Center, Denver 80262, USA
Numerous
articles and several reviews have been published on the role of antioxidants,
and diet and lifestyle modifications in cancer prevention.
However, the potential role of these factors in the management of human cancer
have been largely ignored.
Extensive in vitro studies and limited in vivo studies have revealed that
individual antioxidants such as vitamin A (retinoids), vitamin E (primarily
alpha-tocopheryl succinate), vitamin C (primarily sodium ascorbate) and
carotenoids (primarily polar carotenoids) induce cell differentiation and growth
inhibition to various degrees in rodent and human cancer cells by complex
mechanisms.
The proposed mechanisms for these effects include inhibition of protein kinase C
activity, prostaglandin E1-stimulated adenylate cyclase activity, expression of
c-myc, H-ras, and a transcription factor (E2F), and induction of transforming
growth factor-beta and p21 genes.
Furthermore, antioxidant vitamins individually or in combination enhance the
growth-inhibitory effects of x-irradiation, chemotherapeutic agents,
hyperthermia, and biological response modifiers on tumor cells, primarily in
vitro.
These vitamins, individually, also reduce the toxicity of several standard tumor
therapeutic agents on normal cells.
Low fat and high fiber diets can further enhance the efficacy of standard cancer
therapeutic agents; the proposed mechanisms for these effects include the
production of increased levels of butyric acid and binding of potential mutagens
in the gastrointestinal tract by high fiber and reduced levels of growth
promoting agents such as prostaglandins, certain fatty acids and estrogen by low
fat.
We propose, therefore, a working hypothesis that multiple antioxidant vitamin
supplements together with diet and lifestyle modifications may improve the
efficacy of standard and experimental cancer therapies.
PMID:
10067654 [PubMed - indexed for MEDLINE]
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