Dietary patterns and colorectal adenoma and cancer risk: a review of the epidemiological evidence

A number of studies exploring associations between individual dietary components and colorectal adenoma or cancer risk have yielded conflicting results. The study of food-based dietary patterns in relation to chronic disease risk represents an alternative approach to the evaluation of single dietary exposures in epidemiological investigations. Results from prospective cohort and population-based case-control studies examining associations between dietary patterns and colorectal cancer or adenoma risk were evaluated and described in this review. Despite notable differences in population characteristics, study design, and methods used for characterizing dietary patterns across the different studies, two general dietary patterns were found to modestly predict colorectal adenoma and cancer risk. A healthier pattern consisting of greater intakes of fruits and vegetables, and lower intakes of red and processed meat, appeared protective against colorectal adenoma and cancer incidence. Findings also suggest that a less healthy pattern characterized by higher intakes of red and processed meat, as well as potatoes and refined carbohydrates, may increase risk. Continued research efforts are needed to evaluate the cumulative and interactive effects of numerous dietary exposures on colorectal cancer risk.