Reduced risk of colon cancer with high intake of vitamin E: the Iowa Women's Health Study.
Antioxidant micronutrients, including vitamin E, vitamin C, the carotenoids, and selenium, defend the body against free radicals and reactive oxygen molecules, suggesting a potential for these dietary components in cancer prevention. To investigate whether high intakes of antioxidant micronutrients protect against colon cancer in humans, we analyzed 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 questionnaire in 1986. Through 1990, 212 incident cases of colon cancer were documented. Adjusted for age, total vitamin E intake was inversely associated with the risk of colon cancer (P for trend < 0.0001); the relative risk for the highest compared to the lowest quintile was 0.32 [95% confidence interval (95% CI) 0.19, 0.54]. Further adjustment for total energy intake and other risk factors in proportional hazards regression had little effect on these estimates. The association was not uniform across age groups: the multivariate relative risk of colon cancer for the highest compared to the lowest quintile of total vitamin E intake 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 among women with higher total intakes of vitamins A and C and beta-carotene, and among users of selenium supplements, were not significantly different from 1.0. These prospective data provide evidence that a high intake of vitamin E may decrease the risk of colon cancer, especially in persons under 65 years of age.
Bostick
R M
RM
Division of Epidemology, School of Public Health, University of Minnesota, Minneapolis 55454.
Potter
J D
JD
McKenzie
D R
DR
Sellers
T A
TA
Kushi
L H
LH
Steinmetz
K A
KA
Folsom
A R
AR
D000368:Aged; D003110:Colonic Neoplasms / Q000517:prevention & control*; D004249:DNA Damage; D005260:Female; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D012306:Risk; D014810:Vitamin E / Q000008:administration & dosage*
D014810:Vitamin E