REDUCED RISK OF COLON-CANCER WITH HIGH INTAKE OF VITAMIN-E - THE IOWAWOMENS HEALTH STUDY

Antioxidant micronutrients, including vitamin E, vitamin C, the carote noids, and selenium, defend the body against free radicals and reactiv e oxygen molecules, suggesting a potential for these dietary component s in cancer prevention. To investigate whether high intakes of antioxi dant micronutrients protect against colon cancer in humans, we analyze d data from a prospective cohort study of 35,215 Iowa women aged 55-69 years and without a history of cancer who completed a dietary questio nnaire in 1986. Through 1990, 212 incident cases of colon cancer were documented. Adjusted for age, total vitamin E intake was inversely ass ociated with the risk of colon cancer (P for trend < 0.0001); the rela tive risk for the highest compared to the lowest quintile was 0.32 195 % confidence interval (95% CI) 0.19, 0.54]. Further adjustment for tot al energy intake and other risk factors in proportional hazards regres sion had little effect on these estimates. The association was not uni form across age groups: the multivariate relative risk of colon cancer for the highest compared to the lowest quintile of total vitamin E in take was 0.16 (95% CI 0.04, 0.70) for those 55-59 years old, 0.37 (95% CI 0.12, 1.16) for those 60-64 years old, and 0.93 (95% CI 0.27, 3.25 ) for those 65-69 years old. Multivariate-adjusted relative risks amon g women with higher total intakes of vitamins A and C and beta-caroten e, and among users of selenium supplements, were not significantly dif ferent from 1.0. These prospective data provide evidence that a high i ntake of vitamin E may decrease the risk of colon cancer, especially i n persons under 65 years of age.