Intake of food groups and associated micronutrients in relation to risk of early-stage breast cancer.

Epidemiologic studies have evaluated the risk of breast cancer related to dietary fat intake, but only recently have other dietary factors received attention. Frequent intakes of fruit, vegetables and fiber have been associated with low risk of the disease in some studies but results are inconsistent. In a large case-control study of early-onset breast cancer, we evaluated risk related to a variety of food groups, associated micronutrients and non-nutritive constituents. Cases treated with chemotherapy appeared to have altered reporting of food intake and were excluded. Analyses were restricted to 568 cases with in situ and localized disease and 1,451 population-based controls. Reduced risks were observed for high intake of cereals and grains [odds ratio (OR) = 0.84, 95% confidence interval (CI) = 0.6-1.1 for highest compared with lowest quartile], vegetables (OR = 0.86, 95% CI = 0.6-1.1), beans (OR = 0.87, 95% CI = 0.7-1.2) and fiber from beans (OR = 0.88, 95% CI = 0.7-1.2). However, no trends of decreasing risk across quartiles of increasing intake were observed. Risk was not associated with dietary constituents related to these food groups including dietary fiber, carotenoids, vitamins A, C and E and folate. Incorporation of information from vitamin supplements did not alter the results for micronutrients. Our data suggest that intakes of cereals and grains, vegetables and beans are associated with minimal, if any, reduction in risk of early-stage breast cancer among young women.