Intake of fruits, vegetables, and soy foods in relation to breast cancer risk in Korean women: a case-control study

Abstract

We conducted a case-control study to examine the relationship between fruit, vegetable, and soy food intake and breast cancer risk in Korean women. Incident cases (n=359) were identified through cancer biopsies between March 1999 and August 2003 at two university hospitals in Seoul, Korea. Hospital-based controls (n=708) were selected from patients in the same hospitals during the same period. Subjects were asked by personal interview to indicate their average fruit, vegetable, and soy food intake for a 12-mo period 3 yr prior to the baseline phase. A food intake-frequency questionnaire (98 items) was given by a trained dietitian. Odds ratio (OR) and 95% confidence intervals (CIs) were calculated by unconditional logistic regression after adjustment for confounding factors and total energy intake. There was no association between the intake of total fruits, vegetables, or soy food and breast cancer risk. Increasing consumption of grapes was linked to a significant protective effect against risk of breast cancer (OR=0.66; 95% CI=0.41-0.86; P<0.01). Among the vegetables, reduced risk was observed with high tomato intake (OR=0.62; 95% CI=0.38-0.81; P<0.01). Among soy foods, high consumption of cooked soybeans, including yellow and black soybeans, had an association with reduced breast cancer (OR=0.67; 95% CI=0.45-0.91; P<0.02). Our data suggest that increased intake of some fruits, vegetables, and soy foods may be associated with breast cancer risk reduction in Korean women.