Positive Health Online

Abstract

STONE and PAPAS, Department of Pediatrics, James Quillen College of Medicine, East Tennessee State University, Johnson City 37614-0578 USA write that colorectal cancer is the second most common cause of cancer death in the US for both sexes . A large body of evidence indicates that risk is increased by the mutagenic actions of free radicals in the colon, contributed by dietary factors, intestinal flora and endogenously produced metabolites. The authors write that dietary antioxidants such as vitamin E ought to reduce levels of harmful oxidation products and an absence of vitamin E could result in the oxidation in the colon of polyunsaturated fats to mutagens, including lipid hydroperoxides and malondialdehyde. Also, faecal bacteria generate a high flux of reactive oxygen species including the superoxide radical and inflammatory cells close to the colon can produce reactive nitrogen species including nitrogen dioxide. Evidence suggests that the different forms of vitamin E have distinct biologic potencies, pharmacokinetics and differing abilities to prevent cancer. The authors review (95 references) recent studies regarding the relationship of vitamin E and oxidative stress to colon cancer, emphasising the distinct roles of alpha- and gamma tocopherols. They also discuss the antioxidant/ prooxidant status of ingested foods in relation to antioxidant use for chemo prevention trials for colon cancer.

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References

Stone WL and Papas AM. Tocopherols and the etiology of colon cancer. J Natl Cancer Inst 89(14): 1006-14. Jul 16 1997 .