Micronutrients and the risk of colorectal adenomas.

Recent studies suggest that micronutrients, especially folate, calcium, iron, and antioxidant vitamins, affect the risk of colorectal neoplasia. The objective of this case-control study was to examine the association between these micronutrients and the risk of colorectal adenomas. The study was based on 236 cases with adenomatous polyps or cancer and 409 controls, all colonoscopy patients at University of North Carolina Hospitals between July 1988 and March 1991. After colonoscopy, subjects were interviewed using a semi-quantitative food frequency questionnaire, and average daily nutrient intakes were calculated. Sex-specific odds ratios relative to the lowest quartile of intake for each micronutrient were determined using unconditional logistic regression while adjusting for a number of potential confounders. In women, folate, iron, and vitamin C were inversely related to the risk of adenomas. Folate appeared to be most protective, with women in the highest quartile only 40% as likely to develop adenomas compared with women in the lowest (odds ratio = 0.39, 95% confidence interval 0.15-1.01). In men, greater vitamin E and calcium intakes were associated with reduced risk of adenomas, with vitamin E showing the strongest inverse association. Men in the highest vitamin E quartile had a risk of 0.35 (95% confidence interval 0.14-0.92) relative to those in the lowest. These study results support previous research findings that selected micronutrients protect against colorectal neoplasia.