Relation of calcium, vitamin D, and dairy food intake to incidence of colon cancer among older women. The Iowa Women's Health Study.
To investigate whether a high intake of calcium, vitamin D, or dairy products may protect against colon cancer, the authors analyzed data from a prospective cohort study of 35,216 Iowa women aged 55-69 years 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, intakes of calcium and vitamin D were significantly inversely associated with the risk of colon cancer. The relative risks for the highest quintile of intake as compared with the lowest were 0.52 (95% confidence interval (CI) 0.33-0.82) for calcium and 0.54 (95% CI 0.35-0.84) for vitamin D. After multivariate adjustment, the trends were no longer statistically significant and the relative risks for the highest versus the lowest quintiles of calcium and vitamin D intakes were attenuated: 0.68 (95% CI 0.41-1.11) for calcium and 0.73 (95% CI 0.45-1.18) for vitamin D. Although the multivariate-adjusted findings did not reach statistical significance at p < or = 0.05, when considered in the context of the whole body of literature on this subject, they are consistent with a possible role for calcium or vitamin D in modestly reducing colon cancer risk.
Bostick
R M
RM
Department of Family Practice and Community Health, Medical School, University of Minnesota, Minneapolis 55454.
Potter
J D
JD
Sellers
T A
TA
McKenzie
D R
DR
Kushi
L H
LH
Folsom
A R
AR
D000368:Aged; D002136:Calcium, Dietary; D003110:Colonic Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D003611:Dairy Products; D004032:Diet; D005260:Female; D006801:Humans; D015994:Incidence; D007484:Iowa / Q000453:epidemiology; D008875:Middle Aged; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D014807:Vitamin D
D002136:Calcium, Dietary; D014807:Vitamin D