Relations between vegetable, fruit and micronutrient intake. Implications for odds ratios in a case-control study

Objective: To investigate whether the protection observed for some micronutrients, such as beta-carotene, in several observational studies may simply reflect vegetable and fruit intake. Design: A case-control study conducted in Italy. Subjects: The subjects were 1225 colon cancer patients, 728 rectal cancer patients and 4154 hospital controls. Results: For the 16 micronutrients considered, the more closely a micronutrient was correlated with total vegetable and fruit intake, the more it appeared protective against colorectal cancer. Conclusion: When studying the effect of a nutrient on disease risk in an observational setting, its relation to other nutrients and foods must be taken into account.