Dietary Phytochemical Index and the Risk of Breast Cancer: A Case-Control Study

High intakes of phytochemical-rich foods might have beneficial effects on reducing breast cancer risk. In this study, we assessed the association between the dietary phytochemical index (PI) and breast cancer risk in a sample of premenopausal Turkish women. This case-control study was conducted on 70 newly diagnosed breast cancer cases and matched 70 healthy controls. Dietary intake was assessed using a validated food frequency questionnaire and dietary phytochemical indexes were calculated with two different methods. The mean PI score of participants was 19.9 ± 9.52 and 23.0 ± 8.95 in cases and controls, respectively (p = 0.046). After adjusting for energy intake, the risk of breast cancer significantly increased by 29.5% in the third quartile as compared to the fourth quartile of dietary PI (OR = 0.295, 95%CI = 0.106-0.822). Higher dietary PI was negatively associated with breast cancer risk; therefore, dietary PI may be suggested as an important contributor to dietary intake for breast cancer.